UNIT 5: THE NFIP FLOODPLAIN MANAGEMENT REQUIREMENTS

UNIT 5:

HE NFIP FLOODPLAIN

MANAGEMENT REQUIREMENTS

In this unit

This unit reviews the NFIP standards for floodplain development,

including:

♦ What maps, base flood elevations and other flood data must be

used,

♦ When permits are required,

♦ Ensuring that new development does not cause increased flood-

ing elsewhere,

♦ Standards to ensure that new buildings will be protected from

the base flood, and

♦ Additional requirements for certain types of development.

Unit 6 reviews more restrictive standards that may be required or

recommended for your community. Units 7 through 10 provide guid-

ance on how to administer a program that fulfills the requirements

spelled out in this unit.

NFIP Requirements 5-1

Contents

A. The NFIP’s Regulations.................................................................................. 5-4

NFIP Regulations........................................................................................... 5-4

Community Types.......................................................................................... 5-6

B. Maps and Data................................................................................................. 5-8

NFIP Maps and Data...................................................................................... 5-8

When FIRM and Ground Data Disagree ....................................................... 5-9

Regulating Approximate A Zones ...................................................................10

Small developments...............................................................................5-11

Larger developments.............................................................................. 5-12

Draft Revised NFIP Data.............................................................................5-14

Advisory Flood Hazard Data ....................................................................... 5-15

C. Permit Requirements..................................................................................... 5-17

Development Permit .................................................................................... 5-17

Building permits..................................................................................... 5-18

Small projects......................................................................................... 5-18

Permits from Other Agencies....................................................................... 5-19

D. Encroachments..............................................................................................5-21

Regulatory Floodways ................................................................................. 5-21

Encroachment Review ................................................................................. 5-21

Streams without Floodway Maps................................................................. 5-24

Allowable increases in Flood Heights ......................................................... 5-25

E. New Buildings in A Zones Buildings........................................................... 5-27

Elevation ...................................................................................................... 5-27

Fill.......................................................................................................... 5-27

Piles, posts, piers or columns.................................................................5-28

Walls or crawlspace ............................................................................... 5-29

How high?..............................................................................................5-31

Elevation Certificate .............................................................................. 5-32

Enclosures.................................................................................................... 5-32

Openings ................................................................................................ 5-33

Use ......................................................................................................... 5-36

Floodproofing .............................................................................................. 5-38

NFIP Requirements 5-2

How high?..............................................................................................5-39

Basements .................................................................................................... 5-40

Basement Exceptions................................................................................... 5-40

Basements and LOMR-F Areas................................................................... 5-41

Anchoring .................................................................................................... 5-42

Flood-Resistant Material.............................................................................. 5-43

Accessory Structures.................................................................................... 5-44

Manufactured Homes................................................................................... 5-45

Elevation ................................................................................................ 5-45

Anchoring .............................................................................................. 5-47

Recreational Vehicles .................................................................................. 5-48

AO and AH Zones ....................................................................................... 5-49

A99 and AR Zones....................................................................................... 5-49

F. New Buildings in V Zones ............................................................................ 5-51

Building Location ........................................................................................ 5-51

Elevation on Piles or Columns..................................................................... 5-51

Wind and water loads............................................................................. 5-52

Certification ........................................................................................... 5-54

Breakaway Walls ......................................................................................... 5-54

Coastal AE Zones ........................................................................................ 5-56

G. Other Requirements ...................................................................................... 5-57

Subdivisions................................................................................................. 5-57

Water and Sewer Systems............................................................................ 5-58

Watercourse alterations................................................................................ 5-58

NFIP Requirements 5-3

A. THE NFIP’S REGULATIONS

For a community to participate in the National Flood Insurance Program, it

must adopt and enforce floodplain management regulations that meet or exceed

the minimum NFIP standards and requirements. These standards are intended to

prevent loss of life and property, as well as economic and social hardships that

result from flooding.

The NFIP standards work – as witnessed during floods in areas where build-

ings and other developments are in compliance with them. Nationwide each year,

NFIP-based floodplain management regulations help prevent more than $1 billion

in flood damages.

This unit focuses on the minimum NFIP criteria. In some instances, more re-

strictive state standards may exist, and they must also be met by communities in

the NFIP. They are the subject of the next unit.

NFIP REGULATIONS

The NFIP requirements can be found in Chapter 44 of the Code of Federal

Regulations (44 CFR). Revisions to these requirements are first published in the

Federal Register, a publication the Federal Government uses to disseminate rules,

regulations and announcements.

Most of the requirements related to your community’s ordinance are in Parts

59 and 60. These are included in Appendix E along with the mapping regulations

of Parts 65 and 70.

Figure 5-1 shows how the regulations are organized. The sections are referred

to in shorthand, such as 44 CFR 60.1—Chapter 44, Code of Federal Regulations,

Part 60, Section 1. In this course, excerpts are shown in boxes:

44 CFR 59.2(b) To qualify for the sale of federally-subsidized flood insurance a

community must adopt and submit to the Administrator as part of its application,

flood plain management regulations, satisfying at a minimum the criteria set forth

at Part 60 of this subchapter, designed to reduce or avoid future flood, mudslide

(i.e., mudflow) or flood-related erosion damages. These regulations must include

effective enforcement provisions.

As noted in Unit 2, when your community joined the NFIP, it agreed to abide

by these regulations. When your community’s FIRM was published, it had to

submit its ordinance to FEMA to ensure that it met these requirements.

NFIP Requirements 5-4

Part 59—General Provisions

Subpart A—General

59.1 Definitions

59.2

Description of program

59.3 Emergency program

59.4 References

Subpart B—Eligibility Requirements

59.21 Purpose of subpart

59.22 Prerequisites for the sale of flood insurance

59.23 Priorities for the sale of flood insurance under the regular program

59.24 Suspension of community eligibility

Part 60—Criteria for Land Management and Use

Subpart A—Requirements for Flood Plain Management Regulations

60.1 Purpose of subpart

60.2 Minimum compliance with floodplain management criteria

60.3 Floodplain management criteria for floodprone areas

(a) When there is no floodplain map

(b) When there is a map, but not flood elevations

(d) When there is a floodway mapped

(e) When there is a map with coastal high hazard areas

60.4 Floodplain management criteria for mudslide (i.e., mudflow)-prone areas

60.5 Floodplain management criteria for flood-related erosion-prone areas.

60.6 Variances and exceptions

60.7 Revisions of criteria for floodplain management regulations

60.8 Definitions

Subpart B—Requirements for State Floodplain Management Regulations

Subpart C—Additional Considerations in Managing Flood-Prone, Mudslide (i.e.,

Mudflow)-Prone, and Flood-Related Erosion-Prone Areas

Figure 5-1. 44 CFR Parts 59 and 60

Many state NFIP coordinators have prepared model flood damage prevention

ordinances to assist communities in meeting the NFIP requirements, so it is likely

that your community adopted an ordinance based on the state model.

NOTE: Periodically, the NFIP regulations are revised to incorporate new requirements or

clarify old ones. These changes are published in the Federal Register. Some revisions

require local ordinance amendments. Your community may or may not have made the

amendments needed to stay updated. Before you complete this unit, you should check

with your state NFIP coordinator or FEMA Regional Office to verify that your ordinance is

currently in full compliance with the latest NFIP requirements.

NFIP Requirements 5-5

COMMUNITY TYPES

NFIP regulations identify minimum requirements that communities must ful-

fill to join and stay in the program. The requirements that apply to a particular

community depend on its flood hazard and the level of detail of the data FEMA

provides to the community. The specific requirements are in Section 60.3, and

apply to communities as follows:

♦ 60.3(a) FEMA has not provided any maps or data.

♦ 60.3(b) FEMA has provided a map with approximate A Zones

♦ 60.3(c) FEMA has provided a FIRM with base flood elevations

♦ 60.3(d) FEMA has provided a FIRM with base flood elevations and a map

that shows a floodway

♦ 60.3(e) FEMA has provided a FIRM that shows coastal high hazard areas

(V Zones)

Two important notes:

The NFIP requirements are minimums. As noted in 44 CFR 60.1(d), “Any

floodplain management regulations adopted by a State or a community which are

more restrictive than the criteria set forth in this part are encouraged and shall take

precedence.”

These requirements are cumulative. A 60.3(c) community must comply with

all appropriate requirements of sections 60.3(a) and (b). For example, 60.3(a) in-

cludes basic requirements for subdivisions and utilities that are not repeated in the

later sections. All communities in the NFIP must comply with these subdivision

and utility requirements.

For example, a 60.3(c) community must use the base flood elevations pro-

vided on the FIRM. If that community has an approximate A Zone without a BFE,

it must comply with the requirements of 60.3(b) for that area.

The rest of this unit explores the requirements of 44 CFR 60.3. It is organized

by subject matter, so it will not correspond with the sections in 44 CFR. Where

appropriate, the specific section numbers are referenced.

You should be able to identify where the requirements discussed in this unit

appear in your ordinance. If you cannot find a specific reference or if you are not

comfortable with your ordinance’s regulatory language, contact your state NFIP

coordinator or FEMA Regional Office. FEMA and your state will expect you to

enforce these minimum requirements as agreed to. If you don’t think your ordi-

nance language is clear or up to date, you should consider an amendment to re-

move any doubt.

NFIP Requirements 5-6

This unit covers the minimum requirements for participation in the NFIP. As

noted, communities are encouraged to enact regulatory standards that exceed

these minimums and that are more appropriate for local conditions.

The Community Rating System (CRS) is a part of the

NFIP that rewards communities that implement programs

that exceed the minimums. It is explained in more detail in

Unit 9, Section C. Where provisions that can receive CRS

credit are mentioned in this course, they are highlighted with

the CRS logo.

NFIP Requirements 5-7

B. MAPS AND DATA

Flood maps and flood data were discussed in Units 3 and 4. This section

builds on that information, covering the NFIP requirements as to when and how a

community must use those maps and data.

Basic rule #1: Check to make sure you have the latest flood maps and data

published by FEMA. You must use the latest maps to ad-

minister your floodplain management ordinance.

NFIP MAPS AND DATA

A community must adopt and enforce floodplain management regulations

based on data provided by FEMA (44 CFR 60.2(h)). This includes the floodplain

boundaries, base flood elevations, FIRM zones and floodway boundaries shown

on your current Flood Insurance Rate Map, Flood Boundary Floodway Map

and/or Flood Insurance Study.

44 CFR 60.2(h): The community shall adopt and enforce flood plain manage-

ment regulations based on data provided by the [Federal Insurance] Administra-

tor. Without prior approval of the Administrator, the community shall not adopt

and enforce flood plain management regulations based upon modified data re-

flecting natural or man-made physical changes.

This requirement does not prevent a community from adopting and enforcing

regulations based on data more restrictive than that provided by FEMA. For ex-

ample, a community may want to regulate to an historical flood which was higher

than the BFEs shown on the FIRM. However, such data must be approved by the

FEMA Regional Office before it is used.

This requirement also does not prevent a community from using other techni-

cal data to identify and regulate floodprone areas not shown on FEMA maps. For

example, many cities and urban counties map and regulate areas on small tribu-

tary streams that are not shown on the FIRM.

The community always has a say in what the latest maps and data should be.

FEMA will send you proposed revisions to the official FIRM and you will have

time to review them and submit your comments to FEMA before they are pub-

lished. You also have a formal 90-day appeals period during which to submit your

appeals before BFEs are made final. If you disagree with the FEMA data at any

time and have scientific or technical data to support your position, you should

submit a request for a map revision as noted in Unit 4, Section D, Maintaining

and Revising NFIP Maps.

Annexations: If a property is in a recently annexed area that does not show up

on your community’s map, use the county’s map and base flood elevations

NFIP Requirements 5-8

(BFEs) to determine the flood protection requirements. In fact, you should for-

mally adopt the county’s FIRM in your ordinance to strengthen your basis for

regulating areas not currently shown on your FIRM.

Exceptions: The basic rule does not cover every situation. Four occasions

where a community may vary from the effective FIRM and other data provided

by FEMA are:

♦ When the FEMA data disagree with ground elevations.

♦ When the FEMA data are insufficient. This occurs in approximate A

Zones where base flood elevations and floodway boundaries are not pro-

vided with the FIRM.

♦ When FEMA has provided draft revised data.

♦ When FEMA provides “advisory” flood hazard data.

These situations are discussed below.

Note: these situations only apply to the use of flood data for floodplain manage-

ment purposes. Insurance agents and lenders must use the current FIRM when

determining insurance rates and whether flood insurance is required. If a person

wants to vary from the current FIRM to obtain different premium rates or to not

have to purchase a flood insurance policy, the FIRM must be officially revised or

amended.

WHEN FIRM AND GROUND DATA DISAGREE

The BFEs published in the Flood Insurance Study set the level for flood pro-

tection purposes. The maps are a graphic portrayal of that information.

Since FEMA usually does not have detailed topographic mapping to use in

preparing the flood maps, the flood boundaries are interpolated between cross sec-

tions using whatever topographical information is available. This can result in in-

accuracies in drawing the boundaries on the map.

The BFE in relation to the actual ground elevation sets the floodplain limits

for regulatory purposes. When ground surveys show that a development site is

above the BFE, you can record the data and issue the permit. Then, if the devel-

oper or owner wants the property removed from the Special Flood Hazard Area

designation, he or she can request a Letter of Map Amendment.

It is up to them to apply for a map change, not you. The procedure is dis-

cussed in Unit 4, Section D.

Conversely, if site surveys show that areas considered outside the 100-year

floodplain on published maps are in fact below the BFE, you should require pro-

tection of new buildings to the BFE. Even though a site may be technically out-

NFIP Requirements 5-9

side the mapped SFHA, you are not doing future occupants any favors by ignor-

ing the known flood hazard.

REGULATING APPROXIMATE A ZONES

The second occasion where you may vary from the data provided by FEMA is

in approximate A Zones. Approximate A Zones are those areas not studied by the

detailed hydrologic/hydraulic methods. These areas are shown as “unnumbered A

zones” on the FIRM and “approximate 100-year flood zones” on the Flood

Boundary Floodway Map. The FIS will not contain specific base flood elevations

for approximate study areas nor will there be a floodway/fringe designation on the

FBFM.

44 CFR 60.3(b) When the Administrator has designated areas of special flood

hazards (A zones) by the publication of a community's FHBM or FIRM, but has

neither produced water surface elevation data nor identified a floodway or coastal

high hazard area, the community shall:…

(3) Require that all new subdivision proposals and other proposed developments

(including proposals for manufactured home parks and subdivisions) greater than

50 lots or 5 acres, whichever is the lesser, include within such proposals base

flood elevation data;

(4) Obtain, review and reasonably utilize any base flood elevation and floodway

data available from a Federal, State, or other source, including data developed

pursuant to paragraph (b)(3) of this section, as criteria for requiring that new con-

struction, substantial improvements, or other development in Zone A on the

community's FHBM or FIRM meet the standards …

Regulating development in approximate or unnumbered A Zones is one of the

tougher jobs you’ll face, especially in counties that have large areas of such

zones. 44 CFR Section 60.3(b)(4) requires that you make every effort to use any

flood data available in order to achieve a reasonable measure of flood protection.

Further, many states and local ordinances require a base flood elevation before a

permit can be issued for any development.

Here are some tips in obtaining data needed for unnumbered A Zones. Which-

ever method you use, be sure to record on the permit records where the flood ele-

vation came from. This will help you be consistent with future development in the

same area.

♦ Check with your state NFIP coordinator. Some states have regulations or

guidance on how to obtain regulatory data. Some have repositories of data

or may help conduct a new study.

♦ Check with local flood control, sanitary or watershed districts. Like state

agencies, they may have their own programs for developing new flood

data.

NFIP Requirements 5-10

♦ If a body of water forms a boundary between two communities, the com-

munity on the other side may have a detailed study. Such base flood data

are valid for both sides of a body of water.

♦ Ask the U.S. Army Corps of Engineers, U.S. Department of Agricul-

ture/Natural Resources Conservation Service, or U.S. Geological Survey if

they have knowledge of any flood studies, unpublished reports, or any

data that may pertain to the area in question.

♦ If the property is along a stream that is near state highway structures such

as bridges or culverts, the state highway department may have done a

flood study to properly size the structure.

♦ If the property is on a river with a power-generating dam, the dam owner

may have had to conduct a study for federal licensing.

♦ See if your engineer or the developer will conduct a study to calculate

BFEs.

Data obtained from one of these other sources should be used as long as they:

♦ Reasonably reflect flooding conditions expected during the base flood,

♦ Are not known to be technically incorrect, and

♦ Represent the best data available.

The FEMA publication Managing Floodplain Development in Approximate

Zone A Areas: A Guide for Obtaining and Developing Base (100-Year) Flood

Elevations provides information on a number of methodologies for developing

BFEs in approximate A zones. These methodologies range from detailed methods

that produce BFEs and perform floodway analyses similar to those developed for

a Flood Insurance Study to simplified methods that can be used in isolated areas

where more costly studies cannot be justified.

If your community has approximate A Zones that are likely to be developed,

you should get a copy of this document and have your engineer review it. You can

also download FEMA’s Quick-2 software for computing flood elevations from

the FEMA flood hazard mapping website.

Small developments

If the project is an isolated building, such as a single-family home in an unde-

veloped area or a subdivision or other development that does not meet the thresh-

olds in 44 CFR Section 60.3(b)(3), you still must ensure that the building is pro-

tected from flood damages by meeting the requirements of 44 CFR 60.3(a)(3).

This paragraph requires you to determine if the site is reasonably safe from flood-

ing and, if it is not, that you ensure the building is constructed with methods and

practices that minimize flood damages and meets other construction requirements.

In nearly all cases the only way to do this is to require that the building be ele-

vated to above an elevation that you determine.

NFIP Requirements 5-11

There are several possible ways of establishing this elevation:

♦ Walk the site with the property owner and find a site on high ground for

the building. Sometimes by this method alone you can determine a safe

building site or establish a safe building elevation, particularly in the

floodplain of a small stream. Sometimes detailed topographic maps are

available that may help.

♦ Use historical records or the flood of record (the highest known flood level

for the area). It may be that a recent flood was close to the base flood. If

records of the recent flood can be used, base your regulatory flood eleva-

tions on them (or add a foot or two to the historical flood levels to provide

a margin of error). Before you do this, get a second opinion from your

state NFIP coordinator, FEMA Regional Office or other agency that is fa-

miliar with the flood data you want to use.

♦ Require protection to a set elevation such as at least five feet above grade.

Only use this approach if you feel confident that the five feet of elevation

will provide adequate flood protection to the building.

♦ Require the permit applicant to develop a base flood elevation or develop

one yourself using one of the methods in the FEMA publication Managing

Floodplain Development in Approximate Zone A Areas: A Guide for Ob-

taining and Developing Base (100-Year) Flood Elevations. This will usu-

ally require the services of an engineer, but will be worth the additional

expense if it is the only way to make sure the building is protected from

flood damage. There are several methods of determining BFEs at varying

costs and levels of detail.

The first three methods are not as good as requiring protection to a BFE.

However, they may be more appropriate for small isolated projects where the

costs of developing BFE information will be high relative to the cost of the build-

ing. The third approach will result in lower flood insurance rates than if the build-

ing had no protection, but the rates are not as favorable as they would be if a BFE

were calculated. Examples of the possible rates are discussed in Unit 9, Section B.

Larger developments

You are encouraged to discuss the flood hazard as early as possible in discus-

sions with subdividers and developers of large areas. If a subdivision or planned

unit development will be partially in the floodplain, there may be ways to avoid

building in the flood hazard area, which can save the developer the cost of a flood

study.

44 CFR 60.3(b)(3): [Communities must] Require that all new subdivision propos-

als and other proposed development (including proposals for manufactured

home parks and subdivisions) greater than 50 lots or 5 acres, whichever is the

lesser, include within such proposals BFE data.

NFIP Requirements 5-12

Any subdivision or other large development that meets this threshold must be

evaluated to determine if the proposed site is in an approximate A Zone and

whether BFEs are required. If BFEs are required, the developer must conduct the

required study (the community, state or other agency may provide assistance).

While the study must provide BFEs, you may want to require a floodway delinea-

tion and inclusion of other data needed to ensure that the building sites will be

reasonably safe from flooding.

BFE data are required for the affected lots in the subdivisions shown in Figure

5-2 and Figure 5-3. Figure 5-2 shows a 76-lot subdivision with several lots clearly

affected by an approximate Zone A area. The subdivision depicted in Figure 5-3

is only 12 lots, but BFEs are required because the subdivision covers more than

five acres and clearly shows buildable sites affected by an approximate Zone A

area.

Figure 5-2: Proposed 76-lot subdivision

Figure 5-3: Proposed 6.7-acre subdivision

NFIP Requirements 5-13

In Figure 5-4, the entire approximate Zone A area is to be left as open space.

If the planned subdivision shows the floodplain is contained entirely within an

open space lot, it may not be necessary to conduct a detailed engineering analysis

to develop BFE data.

Figure 5-4: Proposed 76-lot subdivision

44 CFR 65.3: As soon as practicable, but not later than six months after the date

such information becomes available, a community shall notify the Administrator

of [map] changes by submitting technical or scientific data in accordance with this

part.

When a developer prepares a detailed flood study in an approximate A Zone,

you must submit the new flood information to FEMA within six months. The

community can pass that cost on to the developer by requiring that he or she sub-

mit a request for a Letter of Map Revision as a condition of approving the devel-

opment.

CRS credit is provided if BFEs, floodways and related regula-

tory data are provided in areas not mapped by the NFIP. This

credit can be found in Activity 410, Section 411, of the CRS

Coordinator’s Manual or the CRS Application.

DRAFT REVISED NFIP DATA

The third situation where a community may vary from the official FEMA data

is when FEMA has sent some preliminary data to the community for review.

Communities are required to “reasonably utilize” the data from a draft or prelimi-

nary FIRM or flood insurance study.

Four scenarios are possible:

NFIP Requirements 5-14

♦ Where the original FIRM shows an A or V Zone with no BFEs: Use the

draft information. In the absence of other elevation or floodway data, the

draft information is presumed to be the best available.

♦ Where the original FIRM shows an AE or VE Zone with a BFE or flood-

way and the revision increases the BFE or widens the floodway: The draft

revised data should be used. However, if the community disagrees with

the data and intends to appeal, the existing data can be presumed to be

valid and may still be used until the appeal is resolved.

♦ Where the original FIRM shows an AE or VE Zone with a base flood ele-

vation or floodway and the revision decreases the BFE or shrinks the

floodway: The existing data should be used. Because appeals may change

the draft data, the final BFE may be higher than the draft. If you were to

allow new construction at the lower level as shown in the draft, the owners

may have to pay higher flood insurance premiums.

♦ Where the original FIRM shows a B, C or X Zone: NFIP regulations do

not require that the draft revised data be used. However, you are encour-

aged to use the draft data to regulate development, since these areas are

subject to a flood hazard.

If the community intends to appeal preliminary data, it must be done during

the official appeals period. Otherwise, you will have to wait for the new map to

become official and submit a request for a map amendment or revision.

For more information on this issue, see Use of Flood Insurance Study (FIS)

Data As Available Data, FEMA Floodplain Management Bulletin 1-98.

CLOMRs: The above four scenarios are also relevant for a Conditional Letter

of Map Revision or CLOMR. Note the conditional part of a CLOMR. A CLOMR

provides that if a project is constructed as designed, the BFEs can be revised or

modified (or the property in question can be removed from the SFHA)

AFTER the

as-built specifications are submitted AND the final LOMR is issued.

A permit cannot be issued based on a lower BFE proposed by a CLOMR until

the final LOMR is issued. However, you can issue a permit for that part of the

work not dependent on the changes that will result from the LOMR and condition

the full permit upon receipt of the final LOMR.

ADVISORY FLOOD HAZARD DATA

Sometimes FEMA issues advisory data after a major flood where it was found

that the FIRM and/or flood insurance study underestimated the hazard. This in-

formation is provided so communities can ensure that reconstructed buildings are

protected from the true hazard, not the one shown on the FIRM.

When you receive such advisory information, you should “reasonably utilize”

it. If your community agrees with the information, the ordinance should be re-

NFIP Requirements 5-15

vised to adopt it. If it disagrees with the data, you should be ready to explain why

the community is not requiring construction and reconstruction to be protected.

You and your community are not helping residents if you allow them to rebuild

without protection from a known hazard.

For more information on this issue, see Use of Flood Insurance Study (FIS)

Data As Available Data, FEMA Floodplain Management Bulletin 1-98.

NFIP Requirements 5-16

C. PERMIT REQUIREMENTS

Permits are required to ensure that proposed development projects meet the

requirements of the NFIP and your ordinance. Once a person applies for a permit,

you can review the plans and make sure the project complies.

Basic rule #2: A permit is required for all development in the SFHA shown

on your FIRM.

The first step, therefore, is to get people to apply for a permit.

DEVELOPMENT PERMIT

44 CFR 59. Definitions: "Development" means any man-made change to im-

proved or unimproved real estate, including but not limited to buildings or other

structures, mining, dredging, filling, grading, paving, excavation or drilling opera-

tions or storage of equipment or materials.

The NFIP requirements are keyed to “development” in the floodplain. “De-

velopment” means “any man-made change to improved or unimproved real es-

tate.” This includes, but is not limited to:

♦ Construction of new structures

♦ Modifications or improvements to existing structures

♦ Excavation

♦ Filling

♦ Paving

♦ Drilling

♦ Driving of piles

♦ Mining

♦ Dredging

♦ Land clearing

♦ Grading

♦ Permanent storage of materials and/or equipment

44 CFR 60.3(a)(1) [“60.3(a) communities” that do not have a FIRM must] Require

permits for all proposed construction or other development in the community, in-

cluding the placement of manufactured homes, so that it may determine whether

such construction or other development is proposed within flood-prone areas;

If you are a 60.3(a) community, you do not have a FIRM. Consequently, you

must require a permit for all development projects throughout your community.

NFIP Requirements 5-17

You must review each project’s location to determine if it has a flood risk. If it

does, the best way to protect a new building from flood damage is to obtain a BFE

for the site and require that the building be elevated or protected to or above that

BFE.

Building permits

Most communities have long had a system for issuing building permits, but

many have not had a permit system for “development.” Regulating all develop-

ment in floodplains is essential because fill or other material can obstruct flood

flows just as structures can.

Because a “building permit” often covers only construction or modifications

of buildings, this study guide uses the term “development permit.” You should

check your permit system to ensure that in the floodplain, permits are being re-

quired for

ALL projects that meet the definition of development, not just “building”

projects. Make sure you regulate the following in addition to the traditional build-

ing projects:

♦ Filling and grading.

♦ Excavation, mining and drilling.

♦ Storage of materials.

♦ Repairs to a damaged building that do not affect structural members.

♦ Temporary stream crossings

♦ Activities by other government agencies, such as roads, bridges and school

buildings

If your building permit system does not require permits for these activities,

you need to revise your system, enact a new type of “development permit” or oth-

erwise ensure that people apply for a permit for these non-building projects.

Small projects

You have some discretion to exempt obviously insignificant activities from

the permit requirement, such as planting a garden, farming, putting up a mailbox

or erecting a flagpole. You may also want to exempt routine maintenance, such as

painting or re-roofing.

The key is whether the project will present a new obstruction to flood flows,

alter drainage or have the potential to be a substantial improvement. These deter-

minations can only be made by the permit official, not the builder, so make sure

your exemptions are clear. There should be no possibility of a misunderstanding

resulting in construction of a flood flow obstruction or a substantial improvement

without a permit.

NFIP Requirements 5-18

Some communities specifically exempt small projects in their ordinances.

This is the recommended approach, as it avoids challenges that the permit official

arbitrarily decides what projects need permits. Check with your state coordinating

agency and/or FEMA Regional Office before you do this. You may be able to ex-

empt projects (other than filling, grading or excavating) valued at less than, say,

$500.

PERMITS FROM OTHER AGENCIES

44 CFR 60.3(a)(2) requires all NFIP communities to ensure that other federal

and state permits have been obtained. You should not issue your local permit until

you are certain that the other agencies’ requirements are met.

The purpose of this requirement is to help assure that coordination occurs be-

tween various levels of government on projects impacting on floodplains. The

requirement has the added benefit of protecting permit applicants by making sure

they are aware of and obtain all of the permits necessary for a floodplain devel-

opment prior to making irreversible financial investments. Permit applicants are

not well served if they are allowed to proceed with a project only to have work

stopped later by a Federal or State agency because they have not obtained proper

permits.

Some communities allow their permit officials to issue the local permit on the

condition that other required permits are obtained. However, this is not as effec-

tive as holding the local permit until the applicant can show that the other agen-

cies have issued or will issue their permits.

Otherwise, the project may get under way before you are sure that it meets all

legal requirements.

To implement this requirement, you’re encouraged to develop a list of what

permits are required in your jurisdiction. Your state NFIP coordinator should be

able to help.

These development activities may require a state permit:

♦ Construction in the coastal zone.

♦ Construction in floodways or other designated areas.

♦ Stream crossings or projects that affect navigable rivers.

♦ Installation of septic systems.

♦ Subdivision standards or subdivision plat or lot filing requirements.

♦ Manufactured housing (mobile home) park or tie-down requirements.

♦ Public health facilities, such as hospitals and nursing homes.

♦ Alteration of sand dunes.

NFIP Requirements 5-19

♦ Operating a landfill or hazardous materials storage facility.

The more common federal regulations that may require a permit include:

♦ U.S. Army Corps of Engineers Section 404—permits for wetlands filling

♦ U.S. Army Corps of Engineers Section 10—permits for work in navigable

waterways

♦ U.S. Coast Guard—permits for bridges and causeways that may affect

navigation.

♦ U.S. Fish and Wildlife Service—consultations required under Sections 7

and 10 of the Endangered Species Act of 1973.

You should also check with your county; sewer, sanitary or flood control dis-

trict; water management district; and any other local or regional agency that may

regulate certain types of development in the floodplain.

NFIP Requirements 5-20

D. ENCROACHMENTS

Once a permit application is received and the proposed project is ready for re-

view, the next job is to ensure that the project will not impose flood problems on

other properties.

Basic rule #3: Development must not increase the flood hazard on other

properties.

This is more of a concern in riverine situations where a project may dam or

divert flowing water onto other properties or increase flood flows downstream. To

prevent this, communities adopt floodways to designate those areas where flood

flows are most sensitive to changes brought by development.

Communities must regulate development in these floodways to ensure that

there are no increases in upstream flood elevations. For streams and other water-

courses where FEMA has provided BFEs, but no floodway has been designated,

the community must review developments on a case-by-case basis to ensure that

these increases do not occur.

REGULATORY FLOODWAYS

44 CFR 59.1 Definitions: "Regulatory floodway" means the channel of a river or

other watercourse and the adjacent land areas that must be reserved in order to

discharge the base flood without cumulatively increasing the water surface eleva-

tion more than a designated height.

As explained in Unit 3, Section B, the floodway is the central portion of a riv-

erine floodplain needed to carry the deeper, faster moving water. Buildings, struc-

tures and other development activities—such as fill—placed within the floodway

are more likely to obstruct flood flows, causing the water to slow down and back

up, resulting in higher flood elevations.

A floodway is included with most riverine Flood Insurance Studies and will

generally be shown on the Flood Insurance Rate Map (FIRM). Some of the older

Flood Insurance Studies will have a separate floodway map. The community of-

ficially adopts its “regulatory floodway” in its floodplain management ordinance.

ENCROACHMENT REVIEW

All projects in the regulatory floodway must undergo an encroachment review

to determine their effect on flood flows and ensure that they do not cause prob-

lems. Development projects in the flood fringe by definition do not increase flood

heights above the allowable level, so encroachment reviews are not needed.

NFIP Requirements 5-21

44 CFR 60.3(d)(3): [In the regulatory floodway, communities must] Prohibit en-

croachments, including fill, new construction, substantial improvements, and

other development within the adopted regulatory floodway unless it has been

demonstrated through hydrologic and hydraulic analyses performed in accor-

dance with standard engineering practice that the proposed encroachment would

not result in any increase in flood levels within the community during the occur-

rence of the base flood discharge.

The objective of this requirement and the floodplain management ordinance to

ensure that the floodway is reserved to do its natural job: carrying floodwater. The

preferred approach is to avoid all development there.

Once your community adopts its floodway, you must fulfill the requirements

of 44 CFR 60.3(d). The key concern is that each project proposed in the floodway

must receive an encroachment review, i.e., an analysis to determine if the project

will increase flood heights. You may also want to require that this review deter-

mine if the project will cause increased flooding downstream. Note that the regu-

lations call for preventing ANY increase in flood heights. This doesn’t mean you

can allow a foot or a tenth of a foot – it means zero increase. If you do not limit

the increase to zero, small increases in flood heights from individual develop-

ments will cumulatively have significant impacts on flood stages and flood dam-

ages. Under NFIP minimum requirements, it is assumed that there will be no cu-

mulative effects since the permissible rise for any single encroachment is zero.

Projects, such as filling, grading or construction of a new building, must be

reviewed to determine whether they will obstruct flood flows and cause an in-

crease in flood heights upstream or adjacent to the project site.

Projects, such as such as grading, large excavations, channel improvements,

and bridge and culvert replacements, should also be reviewed to determine

whether they will remove an existing obstruction, resulting in increases in flood

flows downstream.

Your community may conduct the encroachment review, or you may require

the developer to conduct it. Most local permit officials are not qualified to make

an encroachment review, so most require that this be done by an engineer at the

developer’s expense.

As the permit reviewer, it is the community’s job to ensure that an activity

will not cause a problem. You have two options for doing this: For every project

you could require the applicant’s engineer to certify that there will be no rise in

flood heights or you can make the determination for minor projects.

Encroachment certification: To ensure that the encroachment review is done

right, you may want to require the developer to provide an encroachment certifi-

cation. This is often called a “no-rise” certification because it certifies that the de-

velopment project will not affect flood heights. An example of a form developed

by the North Carolina state coordinating agency is shown in Figure 5-5.

NFIP Requirements 5-22

The certification must be supported by technical data, which should be based

on the same computer model used to develop the floodway shown on the commu-

nity's map.

“NO-RISE” CERTIFICATION

This is to certify that I am a duly qualified registered professional engineer li-

censed to practice in the State of

It is further to certify that the attached technical data supports the fact that

proposed (Name of Development) will not impact the 100-year flood

elevations, floodway elevations, or floodway widths on

(Name of Stream) at published sections in the Flood Insurance Study for

_______________(Name of Community) dated

(Study Date) and will not impact the 100-year flood elevations, floodway eleva-

tions, or floodway widths at unpublished cross-sections in the vicinity of the pro-

posed development.

Attached are the following documents that support my findings:

Date: _____

Signature:

Title: {SEAL}

Figure 5-5: Example no-rise certification

Although your community is required to review and approve the encroach-

ment review, you may request technical assistance and review from the FEMA

Regional Office or state NFIP Coordinator. If this alternative is chosen, you must

review the technical submittal package and verify that all supporting data are in-

cluded in the package before sending it to FEMA.

Minor projects: Some projects are too small to warrant an engineering study

and the certification. Many of these can be determined using logic and common

sense: a sign post or telephone pole will not block flood flows. Barbed wire farm

fences that will be pushed over or ripped out early in the flood may also be per-

mitted without a certification; however, larger more massive fences could be an

obstruction to flood flows and may require an engineering study and certification.

A driveway, road or parking lot at grade (without any filling) won’t cause an ob-

struction, either.

NFIP Requirements 5-23

Building additions, accessory buildings, and similar small projects can be lo-

cated in the conveyance shadow. This is the area upstream and downstream of an

existing building or other obstruction to flood flows. Flood water is already flow-

ing around the larger obstruction, so the addition of a new structure will not

change existing flood flow.

Determining the limits of the conveyance shadow is illustrated in Figure 5-6.

Small structures located completely within the shadow can be permitted without

the engineering analysis needed for a no-rise certification.

Note: Just because a small structure can be located in the conveyance shadow,

it is still preferable to keep all development out of the floodway. Don’t forget: all

buildings must be elevated or otherwise protected from the base flood.

Figure 5-6. Determining the conveyance shadow

STREAMS WITHOUT FLOODWAY MAPS

If your community has a FIRM with base flood elevations along rivers or

streams, but no mapped floodway, you must evaluate all development to ensure

that it will not increase flood stages by more than one foot.

44 CFR 60.3(c)(10): [Communities must] Require until a regulatory floodway is

designated, that no new construction, substantial improvements, or other devel-

opment (including fill) shall be permitted within Zones A1-30 and AE on the

community's FIRM, unless it is demonstrated that the cumulative effect of the

proposed development, when combined with all other existing and anticipated

development, will not increase the water surface elevation of the base flood more

than one foot at any point within the community.

For the purposes of administering your ordinance, you should treat the entire

riverine floodplain as a floodway. You should require the same encroachment cer-

NFIP Requirements 5-24

tification to ensure that a development project will not obstruct flood flows and

cause increased flooding on other property. This approach is recommended for all

other riverine floodplains without a mapped floodway.

In riverine floodplains where no floodway has been designated, the review

must demonstrate that the cumulative effect of the proposed development, when

combined with all other existing and anticipated development:

♦ Will not increase the water surface elevation of the base flood more than

one foot at any point within the community, and

♦ Is consistent with the technical criteria contained in Chapter 5 (Hydraulic

Analyses) of the Flood Insurance Study: Guidelines and Specifications for

Study Contractors, FEMA-37, 1995.

This review must be required for all development projects, although you may

make the same judgments on minor projects as for floodways. You should pay

particular attention to developments that may create a greater than one-foot in-

crease in flood stages, such as bridges, road embankments, buildings and large

fills.

Note: In some states, floodways are mapped based on allowing flood heights

to increase by less than one foot. In those states, the encroachment certification

must be based on that more restrictive state standard, not the FEMA standard that

allows a one-foot rise.

ALLOWABLE INCREASES IN FLOOD HEIGHTS

In some situations, it may be in the public interest to allow increase in flood

heights greater than those allowed under the NFIP regulations.

For example, it would be hard to build a flood control reservoir without affect-

ing flood heights. Because a dam would have a major impact on flood heights,

there needs to be a way to permit such projects, especially those that are intended

to reduce flooding.

However, when the project will change the flood level, maps must be changed

to reflect the new hazard.

44 CFR 60.3(d)(4) Notwithstanding any other provisions of § 60.3, a community

may permit encroachments within the adopted regulatory floodway that would re-

sult in an increase in base flood elevations, provided that the community first ap-

plies for a conditional FIRM and floodway revision, fulfills the requirements for

such revisions as established under the provisions of § 65.12, and receives the

approval of the Administrator.

If your community proposes to permit an encroachment in the floodway or the

floodplain that will cause increases in the BFE in excess of the allowable level,

NFIP Requirements 5-25

you’re required to apply to the FEMA Regional Office for conditional approval of

such action prior to permitting the project to occur.

As part of your application for conditional approval, you must submit:

♦ A complete application and letter of request for conditional approval of a

change in the FIRM or a Conditional Letter of Map Revision (CLOMR),

along with the appropriate fee for the change (contact the FEMA Regional

Office for the fee amount).

♦ An evaluation of alternatives which, if carried out, would not result in an

increase in the BFE more than allowed, along with documentation as to

why these alternatives are not feasible.

♦ Documentation of individual legal notice to all affected property owners

(anyone affected by the increased flood elevations, within and outside of

the community) explaining the impact of the proposed action on their

properties.

♦ Concurrence, in writing, from the chief executive officer of any other

communities affected by the proposed actions.

♦ Certification that no structures are located in areas which would be af-

fected by the increased BFE (unless they have been purchased for reloca-

tion or demolition).

♦ A request for revision of BFE determinations in accordance with the pro-

visions of 44 CFR 65.6 of the FEMA regulations.

Upon receipt of the FEMA conditional approval of the map change and prior

to approving the proposed encroachments, you must provide evidence to FEMA

that your community’s floodplain management ordinance incorporates the post-

project condition BFEs.

NFIP Requirements 5-26

E. NEW BUILDINGS IN A ZONES BUILDINGS

Basic rule #4: New, substantially improved or substantially damaged build-

ings must be protected from damage by the base flood.

In this course, the term “building” is the same as the term “structure” in the

NFIP regulations. Your ordinance may use either term.

44 CFR 59.1 Definitions: "Structure" means, for flood plain management pur-

poses, a walled and roofed building, including a gas or liquid storage tank, that is

principally above ground, as well as a manufactured home.

The term “building” or “structure” does not include open pavilions, bleachers,

carports and similar structures that do not have at least two rigid walls and a roof.

How to determine if a building is substantially improved or substantially dam-

aged is discussed in Unit 8. In this unit, consider the term “building” as an all-

encompassing term that includes substantial improvements and repairs of substan-

tial damage to a building.

Residential and nonresidential buildings are treated differently. A residential

building must have a higher level of protection—if it is to be built in the flood-

plain, it must be elevated above the BFE. Nonresidential buildings, on the other

hand, may be elevated or floodproofed (made watertight below the BFE).

ELEVATION

44 CFR 60.3(c)(2) [Communities must] Require that all new construction and

substantial improvements of residential structures within Zones A1-30, AE and

AH zones on the community's FIRM have the lowest floor (including basement)

elevated to or above the base flood level…

In Zones A1-A30, AE and AH, all new construction and substantial improve-

ments of residential structures must be elevated so that the lowest floor (including

the basement) is elevated to or above the BFE. This can be done in one of three

ways:

♦ Elevation on fill.

♦ Elevation on piles, posts, piers or columns.

♦ Elevation on walls or a crawlspace.

Fill

Fill can be used by itself or in conjunction with other types of foundations to

raise the lowest floor of a building above the BFE. However, restrictions to the

NFIP Requirements 5-27

use of fill apply in floodways where fill would cause an increase in flood heights

and in V zones where it would act as an obstruction to waves.

Some communities require or encourage the use of fill to elevate residential

buildings because they consider fill a safer construction method since the building

itself is not in contact with floodwaters. Other communities limit the use of fill in

the flood fringe to protect flood storage capacity or require compensatory storage,

which is discussed in Unit 6, Section C.

Where fill is the method of choice, it should be properly designed, installed in

layers and compacted. Simply adding dirt to the building site may result in differ-

ential settling over time.

The fill should also be properly

sloped and protected from erosion

and scour during flooding. To

provide a factor of safety for the

building and its residents, it is recom-

mended that the fill extend 10 – 15

feet beyond the walls of the building

before it drops below the BFE.

Piles, posts, piers or

columns

Piles, piers, posts or columns are

appropriate foundations for elevating

buildings above the BFE where there

is deeper flooding, fill is not feasible

or not allowed, or for areas with high

velocity flooding. Where flooding is

likely to have high velocities or

waves, leaving the area below the

building free of obstruction with no

lower area enclosure is preferred. As

illustrated in Figure 5-8, this permits

unrestricted flow of floodwater under

the building. There will be less force

applied to the building by

floodwaters and less impact on flood

heights than if solid walls were used.

Figure 5-7. These two new build-

ings elevated on fill were not

damaged by this 100-year flood.

NFIP Requirements 5-28

Figure 5-8. Elevation on piers

Walls or crawlspace

The third elevation technique is to build on solid walls. In shallower flooding

areas, this elevation technique is the same as creating a crawlspace—a foundation

of solid walls that puts the lowest floor above the flood level. In deeper flooding

areas this often results in elevating the building a full story and creation of an en-

closed area below the BFE.

When solid walls are used, care must be taken to ensure that hydrostatic or

hydrodynamic pressure does not damage the walls. As discussed in Unit 1, Sec-

tion B, these water pressures can cause a solid wall to collapse damaging the ele-

vated portion of the building.

There are two ways to prevent this:

♦ Stem walls can be used on two sides parallel to the flow of water. The

other two sides are kept open (Figure 5-9). This minimizes the obstruction

to floodwaters and lessens pressure on the foundation.

♦ The walls can be built with openings large enough to allow floodwaters to

flow in and out, preventing differential pressures on the walls. Openings

are required any time there is a fully enclosed area below the BFE. This is

discussed in more detail in the later section on enclosures.

NFIP Requirements 5-29

Figure 5-9: Building elevated on parallel stem walls.

Figure 5-10: Building elevated on crawlspace with openings.

When a crawlspace is used to elevate the building above the base flood eleva-

tion, it creates an enclosed area below the BFE that must meet all requirements

that apply to enclosures including the openings requirement (see the sections of

this Unit on Enclosures and Openings). In addition the floor of the crawlspace

must be at or above the lowest adjacent grade to the building to minimize hydro-

NFIP Requirements 5-30

static pressures against the crawlspace walls and the ponding of water within the

crawl space after a flood.

Recently FEMA issued a policy allowing communities to permit construction

of crawlspaces with their floors below grade in the Special Flood Hazard Area

(SFHA) under certain conditions. Communities that wish to allow below-grade

residential crawlspace construction must require that the interior grade of the

crawlspace is no more than two feet below the lowest adjacent grade, the height

of the crawlspace measured from the interior grade of the crawlspace to the top of

the crawlspace wall does not exceed four feet at any point, and the building meets

other limitations. These communities must adopt these requirements as part of

their floodplain management ordinance. Below-grade crawlspaces that meet these

requirements will not be considered basements, but the buildings will still have

higher flood insurance rates than if the same crawlspace had its floor at or above

lowest adjacent grade.

Technical Bulletin 11-01 Crawlspace Construction for Buildings Located in

Special Flood Hazard Areas provides a best practices approach for crawlspace

construction. While communities may allow below-grade crawlspace construc-

tion, the Technical Bulletin continues to recommend that the interior of the crawl-

space be backfilled so that the interior grade is level to or higher than the lowest

adjacent grade (LAG) to the building. The Technical Bulletin offers appropriate

considerations and guidance for below-grade crawlspace construction. Communi-

ties that wish to allow below-grade crawlspaces should refer to the Technical Bul-

letin for the specific requirements that must be incorporated into their floodplain

management ordinance.

How high?

NFIP regulations require that the lowest floor of a building must be elevated

above the BFE. Note three things about this minimum requirement:

1. The term “lowest floor” includes a basement because all usable portions of

a building must be protected from flood damage.

44 CFR 59.1. Definitions: "Lowest Floor" means the lowest floor of the lowest en-

closed area (including basement). An unfinished or flood resistant enclosure, us-

able solely for parking of vehicles, building access or storage in an area other

than a basement area is not considered a building's lowest floor; provided, that

such enclosure is not built so as to render the structure in violation of the appli-

cable non-elevation design requirements of section 60.3.

2. The minimum requirement is to elevate to the BFE. In the next unit, we

will discuss freeboard, an extra margin of protection that requires the low-

est floors to be one or more feet above the BFE.

3. In A Zones, under the minimum NFIP requirement, the lowest floor is

measured from the top of the floor (Figure 5-11). However, all portions of

NFIP Requirements 5-31

the building below the BFE must be constructed with flood resistant mate-

rials and building utility systems (including ductwork) must be elevated

above the BFE or floodproofed (made watertight) to that elevation. To

meet these requirements, it is recommended that buildings on elevated

foundations, such as piles or a crawlspace, have supporting beams or floor

joists and building utility systems elevated to or above the BFE to protect

them from flood damage. This is generally easier than using flood resis-

tant materials for floor support systems or floodproofing building utility

systems.

Figure 5-11. In A Zones: the top of the

floor is the reference level

Elevation Certificate

Because most new buildings built in the floodplain are residences, elevating

them is one of the most important requirements of the NFIP. To ensure that a

building is elevated above the BFE, the lowest floor is surveyed and an elevation

certificate is obtained and kept by the local permit office. This is discussed in

more detail in Unit 7, Section G.

ENCLOSURES

Enclosures are areas created by a crawlspace or solid walls that fully enclose

areas below the BFE. They deserve special attention for two reasons:

♦ The walls of enclosed areas are subject to flood damage from hydrostatic

and hydrodynamic forces.

♦ People are tempted to convert enclosures that are intended to be flooded

into areas that can sustain damage in a flood.

NFIP Requirements 5-32

NFIP regulations allow certain uses in enclosures below the BFE because they

can be designed so that they are subject to minimal flood damage. Three uses are

allowed:

♦ building access

♦ vehicle parking

♦ storage.

The storage permitted in an enclosed lower area should be limited to that

which is incidental and accessory to the principal use of the structure. For exam-

ple, if the structure is a residence, storage should be limited to items such as lawn

and garden equipment, bicycles, and snow tires which either have a low damage

potential or that can be easily moved to the elevated portion of the building if

there is a flood.

The floodplain regulation requirements can be easier to accept if owners and

builders are encouraged to think about the enclosed lower areas as usable space. If

a building has to be elevated, say, five feet above grade, the owner should be en-

couraged to go up eight feet. This allows the lower area to be used for parking—

and provides three extra feet of flood protection.

However, if the lower area is enclosed, there is a tendency for the owner to

forget about the flood hazard and convert the enclosure to a bedroom or other fin-

ished room. This must be prevented.

Since floodwaters are intended to enter the enclosure—it must be built of

flood-resistant materials (see the section on flood-resistant materials do determine

which are acceptable). Not allowed are finishings such as carpeting, paneling, in-

sulation (both cellulose and fiberglass) and gypsum wallboard (also known as

drywall and sheet rock).

Utilities that serve the upper level also must be protected from flood damage.

Consequently, a furnace cannot be put in an enclosure unless it is located above

the BFE. This is explained in more detail in Engineering Principles and Practices

for Flood Damage-Resistant Building Support Utility Systems, FEMA 348, and

November 1999. When the lower area enclosure is used to provide access to the

upper level, a stairway can be designed that provides this access yet is resistant to

flood damage. Installing an elevator is more difficult, but there are ways to design

and install an elevator that will face minimal flood damage, as explained in Eleva-

tor Installation for Buildings Located in Special Flood Hazard Areas, FIA-TB-4,

FEMA 1993.

Openings

As noted in Unit 1, solid walls can collapse from hydrostatic pressure if

floodwaters get too deep outside the building. To prevent this, an enclosure must

NFIP Requirements 5-33

have openings to allow floodwaters to enter and leave, thus automatically equaliz-

ing hydrostatic flood forces on both sides of the walls.

44 CFR 60.3(c)(5) [Communities must] Require, for all new construction and

substantial improvements, that fully enclosed areas below the lowest floor that

are usable solely for parking of vehicles, building access or storage in an area

other than a basement and which are subject to flooding shall be designed to

automatically equalize hydrostatic flood forces on exterior walls by allowing for

the entry and exit of floodwaters. Designs for meeting this requirement must ei-

ther be certified by a registered professional engineer or architect or meet or ex-

ceed the following minimum criteria: A minimum of two openings having a total

net area of not less than one square inch for every square foot of enclosed area

subject to flooding shall be provided. The bottom of all openings shall be no

higher than one foot above grade. Openings may be equipped with screens, lou-

vers, valves, or other coverings or devices provided that they permit the auto-

matic entry and exit of floodwaters.

You can be sure the openings are adequate by using one of two methods.

The first method is to have the design meet or exceed the following three cri-

teria:

1. The bottom of the openings must be no higher than one foot above grade

(see Figure 5-12).

2. The openings shall be installed on at least two walls of the enclosure to

ensure that at least one will work if others get blocked or plugged.

3. Provide a minimum of two openings having a net area of not less than one

square inch for every square foot of enclosed area that is subject to flood-

ing. If the area of the enclosure is 1,000 square feet, the area of the open-

ings combined must total at least 1,000 square inches.

For example, removing a concrete block from a block wall results in an 8”

x 16” or 128 square inches opening (see Figure 5-12). To determine how

many openings would be needed, divide the square footage of the floor

area by 128.

Example 1: 1,280 square foot house = 10 10 openings will be needed

128 square inches/opening

Example 2: 2,000 square foot house

= 15.62 16 openings will be needed

128 square inches/opening

If the opening is covered by a standard crawlspace vent cover or grate, the

net area of the opening must be used and the number of openings increased

accordingly. Net areas can be found on manufacturers specifications or es-

timated if specifications are not available.

NFIP Requirements 5-34

The second method of meeting the requirement is to have the design certified

by a registered professional engineer or architect as meeting the requirement to

automatically equalize hydrostatic forces on exterior walls by allowing for the

entry and exit of floodwaters. Under some circumstances it may be possible to

vary the size or location of the openings based on this certification.

Openings may be equipped with screens, louvers, valves or other coverings or

devices to keep animals out of the enclosure. However, any covering must permit

the automatic flow of floodwater in both directions.

The opening sizes in the previous examples and in Figure 5-12 are based on

the size of standard crawlspace vents, which most building codes require to be

installed in a crawlspace for ventilation purposes. Often these are located close to

the floor in order to circulate air around the floor joists.

Figure 5-12. Opening location in solid foundation wall

Air vents are located well above the ground in an elevated house and would

not meet the NFIP requirement that the bottom of the opening be within one foot

of grade. However, NFIP requirements and building codes can be satisfied by the

same vents if they meet the three criteria listed above.

Garage doors cannot be used to satisfy this requirement because they do not

permit the automatic flow of floodwaters. However, garage doors may have vents

in them that meet the above criteria.

Openings are not required for stem wall foundations that have been backfilled

with a concrete floor slab poured that is supported by the fill.

For further guidance, refer to Openings in Foundation Walls, FIA-TB-1

(FEMA 1993).

NFIP Requirements 5-35

Use

Enclosed areas are designed to be flooded and can be used only for parking

vehicles, storage or access to the elevated living area—uses that can be designed

so they are subject to little or no flood damage.

The type of storage permitted in an enclosed lower area should be limited to

that which is incidental and accessory to the principal use of the structure. For in-

stance, if the structure is a residence, the enclosure should be limited to storage of

lawn and garden equipment, snow tires, and other low damage items, which can

be conveniently moved to the elevated part of the building.

The interior portion of an enclosed area should not be partitioned or finished

into separate rooms, except to separate the garage from the access and storage ar-

eas.

If a building is elevated eight feet or more, regulating the use of the enclosure

presents special problems. Over time, the owner may forget the flood hazard and

want to convert the floodable area into a finished room. Such an action would in-

crease the flood damage potential for the building and violate the conditions of

the building permit.

However, because the room is hidden behind walls, it can be very hard for the

permit office to catch such a conversion. You should carefully check new build-

ing plans for signs, such as roughed in plumbing and sliding glass doors that indi-

cate that the owner may expect to finish the area in the future. You should also

clearly state on your permit what the limitations are on construction and use of the

enclosed area.

One way to help prevent conversions is to have the owner sign a nonconver-

sion agreement. An example developed by the North Carolina State NFIP Coordi-

nator is in Figure 5-13.

NFIP Requirements 5-36

____________________________________________________________________

This DECLARATION made this ___ day of __________, 20__, by __________________

(“Owner”) having an address at _________________________________________________

WITNESSETH:

WHEREAS, the Owner is the record owner of all that real property located at

____________________________ in the City of ______________________ in the County of

__________________, designated in the Tax Records as ___________________________.

WHEREAS, the Owner has applied for a permit or variance to place a structure on that prop-

erty that either (I) does not conform, or (2) may be noncompliant by later conversion, to the strict

elevation requirements of Article _______ Section _______ of the Floodplain Management Ordi-

nance of ______________ (“Ordinance”) and under Permit Number _______ (“Permit”).

WHEREAS, the Owner agrees to record this DECLARATION and certifies and declares that

the following covenants, conditions and restrictions are placed on the affected property as a condi-

tion of granting the Permit, and affects rights and obligations of the Owner and shall be binding on

the Owner, his heirs, personal representatives, successors and assigns.

UPON THE TERMS AND SUBJECT TO THE CONDITIONS, as follows:

1. The structure or part thereof to which these conditions apply is: __________________

_________________________________________________________________________ .

2. At this site, the Base Flood Elevation is _______ feet above mean sea level, National Geo-

detic Vertical Datum.

3. Enclosed areas below the Base Flood Elevation shall be used solely for parking of vehicles,

limited storage, or access to the building. All interior walls, ceilings and floors below the Base Flood

Elevation shall be unfinished or constructed of flood resistant materials. Mechanical, electrical or

plumbing devices shall not be installed below the Base Flood Elevation.

4. The walls of the enclosed areas below the Base Flood Elevation shall be equipped and re-

main equipped with vents as shown on the Permit.

5. Any alterations or changes from these conditions constitute a violation of the Permit and

may render the structure uninsurable or increase the cost for flood insurance. The jurisdiction issu-

ing the Permit and enforcing the Ordinance may take any appropriate legal action to correct any

violation.

6. Other conditions: _________________________________________________

In witness whereof the undersigned set their hands and seals this _______ day of

______________, 20 __.

____________________________ ____________________________ (Seal)

Owner

____________________________ ____________________________ (Seal)

Witness

Figure 5-13: Example Nonconversion agreement

NFIP Requirements 5-37

FLOODPROOFING

Nonresidential buildings must be elevated or floodproofed. If they are ele-

vated, they must meet the same standards as for residential buildings that were

just reviewed. Elevation is the preferred method of flood protection because it is

more dependable. Elevated commercial and industrial buildings can often be de-

signed so that they can continue to operate during a flood reducing or eliminating

business disruptions. Also, it will generally prove to be less expensive to elevate

a non-residential building than to floodproof it. However, there will be situations

where floodproofing may be the only feasible alternative for protecting a nonresi-

dential building.

44 CFR 59.1. Definitions: "Flood proofing" means any combination of structural

and non-structural additions, changes, or adjustments to structures which reduce

or eliminate flood damage to real estate or improved real property, water and

sanitary facilities, structures and their contents.

44 CFR 60.3(c)(3) [Communities must] Require that all new construction and

substantial improvements of non-residential structures within Zones A1-30, AE

and AH zones on the community's firm (i) have the lowest floor (including base-

ment) elevated to or above the base flood level or, (ii) together with attendant util-

ity and sanitary facilities, be designed so that below the base flood level the

structure is watertight with walls substantially impermeable to the passage of wa-

ter and with structural components having the capability of resisting hydrostatic

and hydrodynamic loads and effects of buoyancy;

44 CFR 60.3(c)(4) [Communities must] Provide that where a non-residential

structure is intended to be made watertight below the base flood level, (i) a regis-

tered professional engineer or architect shall develop and/or review structural

design, specifications, and plans for the construction, and shall certify that the

design and methods of construction are in accordance with accepted standards

of practice for meeting the applicable provisions of paragraph (c)(3)(ii) or (c)(8)(ii)

of this section, and (ii) a record of such certificates which includes the specific

elevation (in relation to mean sea level) to which such structures are floodproofed

shall be maintained with the official designated by the community under

§59.22(a)(9)(iii);

For the purposes of regulating new construction, floodproofing is defined

measures incorporated in the design of the building so that below the BFE:

♦ Walls are watertight (substantially impermeable to the passage of water),

♦ Structural components can resist hydrostatic and hydrodynamic loads and

effects of buoyancy, and

♦ Utilities are protected from flood damage.

Most floodproofing is appropriate only where floodwaters are less than three

feet deep, since walls and floors may collapse under higher water levels.

NFIP Requirements 5-38

A registered professional engineer or architect must prepare the building plans

and certify the floodproofing measures, preferably using the FEMA Floodproof-

ing Certificate form. This is discussed in more detail in Unit 7, Section G.

Floodproofing techniques that require human intervention are allowed but

should be discouraged. Human intervention means that a person has to take some

action before the floodwater arrives, such as turn a valve, close an opening or

switch on a pump. There are many potential causes of failure for these techniques,

including inadequate warning time, no person on duty when the warning is issued,

the responsible person can’t find the right parts or tools, the person is too excited

or too weak to install things correctly, and/or the electricity fails.

Before you approve plans for a building that relies on human intervention to

be floodproofed, you should make sure that there are plans and precautions to

keep such problems from occurring. Techniques that rely on human intervention

should only be allowed in areas with adequate warning time and in situations

where there will be someone present who is capable of implementing or installing

the required measures.

More information on floodproofing can be found in FEMA’s Technical Bulle-

tin 3-93, Non-Residential Floodproofing Requirements and Certification for

Buildings Located in Special Flood Hazard Areas (FIA-TB-3. 1993)

How high?

The minimum NFIP requirement is to floodproof a building to the BFE. How-

ever, when it is rated for flood insurance, one foot is subtracted from the flood-

proofed elevation. Therefore, a building has to be floodproofed to one foot above

the BFE to receive the same favorable insurance rates as a building elevated to the

BFE. Unit 9, Section B, discusses this in more detail.

NFIP Requirements 5-39

BASEMENTS

For the purposes of the NFIP, a basement is defined as any area that is sub-

grade on all sides. The “lowest floor” of a building is the top of the floor of the

basement

if there is a basement. Since the “lowest floor” of a residential building

must be at or above the BFE, it will be highly unusual to construct a basement in a

floodplain that met these requirements.

44 CFR 59.1 Definitions: "Basement" means any area of the building having its

floor subgrade (below ground level) on all sides.

Note that “walkout basements,” "daylight basements" or "terrace levels" are

usually subgrade on only three sides, with the downhill side at or above grade.

Thus, they are not considered basements for either floodplain management or

flood insurance rating purposes (but they are still the lowest floor of a building for

floodplain management and insurance rating purposes). If these areas are used

only for parking, access, or storage and they meet other ordinance requirements,

they can be regulated as enclosures below an elevated building and not be consid-

ered the lowest floor of the building.

On the other hand, cellars, the lower level of a split-level or bi-level house,

garden apartments and other finished floors below grade are considered base-

ments under NFIP regulations.

Since the lowest floor of a residential building must be above the BFE, the

only way to build a residential basement in the floodplain under NFIP minimum

requirements is if it is elevated on fill and surrounded by fill. Floodproofed non-

residential basement are allowed, provided they meet the requirements discussed

in the previous section on floodproofing.

BASEMENT EXCEPTIONS

A few communities have obtained exceptions to the NFIP regulations that al-

low them to permit floodproofed residential basements. The soil types and flood-

ing conditions in these communities allow construction of floodproofed base-

ments that are not subject to damage by hydrostatic or hydrodynamic forces.

A community may apply for an exception to allow floodproofed residential

basements if it can demonstrate flood depths are less than five feet, velocities are

less than five feet per second, there is adequate warning time for the site and it has

appropriate construction requirements. This exception is explained in 44 CFR

60.6(c).

Buildings with floodproofed basements must have their design certified by a

registered engineer or architect and are more difficult and more expensive to con-

struct than buildings elevated above the BFE. Improperly designed or constructed

NFIP Requirements 5-40

basements can collapse or otherwise fail resulting in major damage to the struc-

ture.

BASEMENTS AND LOMR-F AREAS

It has become a common practice in some areas of the country to fill an area

to above the BFE and then obtain a Letter of Map Revision based on fill (LOMR-

F) to remove the land from the floodplain. Once the land is no longer in the

floodplain, the builder obtains permits to build residences with basements below

the BFE. This practice has raised a number of issues and concerns:

♦ The procedure was being used to get around community floodplain man-

agement ordinances.

♦ Buildings with basements below BFE were being built too close to the

edges of these fills that could be subject to severe flood damage if the

basement walls are subjected to hydrostatic pressure from surface water or

groundwater during flooding.

♦ LOMR-Fs for nearly identical buildings were being granted or not granted

based on the date the LOMR was applied for and not on the risk to the

building.

FEMA issued a final rule on May 4, 2001 revising LOMR-F procedures to

address these issues. The new procedure places responsibility back in the hands

of the community by requiring that, before a LOMR-F is granted, the community

sign a community acknowledgement form and make findings that:

♦ The project, including any buildings, meets all the requirements of the

community’s floodplain management ordinance, and

♦ Any existing or future development on the filled area is “reasonably safe

from flooding”.

FEMA will not act on a LOMR-F request without this acknowledgement.

44 CFR 65.2(c) “Reasonably safe from flooding” means that base flood waters

will not inundate the land or damage structures to be removed from the SFHA

and that any subsurface waters related to the base flood will not damage exist-

or proposed buil

s.”

FEMA has issued Technical Bulletin 10-01 Ensuring That Structures Built on

Fill In or Near Special Flood Hazard Areas Are Reasonably Safe From Flooding

to provide guidance on how to make the determination that an area is “reasonably

safe from flooding”. The risk to buildings built in these areas will vary depend-

ing on soil conditions, the location of the building relative to the edge of the fill,

and whether the building will have a basement below the BFE.

NFIP Requirements 5-41

The safest method of constructing a building on filled land removed from the

SFHA is to elevate the entire building above BFE. If basements are to be built in

these areas, Technical Bulletin 10-01 provides a simplified method for determin-

ing whether those basements will be “reasonably safe from flooding”.

Communities have asked for guidance on how they can ensure that future

buildings placed on the property will be “reasonably safe from flooding” since,

once the LOMR-F is issued, the land is no longer in the SFHA and generally is

not subject to their floodplain management ordinance. Communities have several

options they can use.

They can withhold signing the acknowledgement until the LOMR-F applicant

provides sufficient information on the location and type of proposed buildings to

evaluate those building sites against the criteria in Technical Bulletin 10-01. For

example, the community could require submission of a subdivision plat or grading

plan showing future building locations.

They could adopt or use other requirements that allow them to ensure any fu-

ture buildings on the filled property remain reasonably safe from flooding. For

example, a community may have building code requirements to ensure that any

future basements are properly constructed to resist damage from groundwater.

Technical Bulletin 10-01 provides a number of other alternatives for ensuring

that unimproved land is “reasonably safe from flooding” and stays that way.

Communities have the option of requiring that the applicant submit any engineer-

ing information necessary to make the determination.

The criteria in Technical Bulletin 10-01 can also be used to ensure that build-

ings built with basements that are adjacent to the floodplain are constructed in a

way that minimizes potential damages from groundwater during a flood.

For further information, see Technical Bulletin 10-01 Ensuring that structures

Built on Fill in or Near Special Flood Hazard Areas are Reasonably Safe from

Flooding in Accordance with the National Flood Insurance Program (TB 10-01).

ANCHORING

44 CFR 60.3(a)(3) …If a proposed building site is in a flood-prone area, all new

construction and substantial improvements shall (i) be designed (or modified)

and adequately anchored to prevent flotation, collapse, or lateral movement of

the structure resulting from hydrodynamic and hydrostatic loads, including the ef-

fects of buoyancy…

Both elevated and floodproofed buildings must be properly anchored to stabi-

lize them against flood forces. This means anchoring the building to its founda-

tion and ensuring that the foundation won’t move. Therefore, you need to make

sure there is adequate protection against hydrostatic and hydrodynamic forces and

erosion and scour that can undercut the foundation.

NFIP Requirements 5-42

In areas of shallow flooding and low flood velocities, normal construction

practices suffice. Additional anchoring measures, such as reinforcing crawlspace

walls, using deeper footings, using extra bolts to connect the sill to the foundation,

or installing rods to connect the cap to the sill, should be required in three situa-

tions:

♦ Where the flood flows faster than five feet per second.

♦ In coastal areas subject to waves and high winds.

♦ In manufactured or mobile homes (see the section on Manufactured Ho-

mes for details).

In some areas it may be necessary to use foundations such as piles or piers

which provide less resistance to floodwaters.

If your community has any of these conditions, you should see if there are

state standards that take these into account, such as state coastal construction or

manufactured housing (mobile home) tie-down regulations. If not, it is recom-

mended that the builder’s architect or engineer sign a statement saying the design

of the building includes “anchoring adequate to prevent flotation, collapse and

lateral movement” during the base flood.

FLOOD-RESISTANT MATERIAL

Whether a building is elevated or floodproofed, it is important that all parts

exposed to floodwaters be made of flood-resistant materials (Figure 5-14). This

includes all portions of the building below the BFE including foundation elements

such as floor beams and joists and any below BFE enclosures.

44 CFR 60.3(a) (3) …If a proposed building site is in a flood-prone area, all new

construction and substantial improvements shall (ii) be constructed with materials

resistant to flood damage…

“Flood-resistant materials” include any building product capable of withstand-

ing direct and prolonged contact with floodwaters without sustaining significant

damage. “Prolonged contact” means at least 72 hours, and “significant damage” is

any damage requiring more than low-cost cosmetic repair (such as painting).

NFIP Requirements 5-43

♦ Concrete, concrete block or glazed brick

♦ Clay, concrete or ceramic tile

♦ Galvanized or stainless steel nails, hurricane clips and connectors (in areas

subject to saltwater flooding)

♦ Indoor-outdoor carpeting with synthetic backing (do not fasten down)

♦ Vinyl, terrazzo, rubber or vinyl floor covering with waterproof adhesives.

♦ Metal doors and window frames.

♦ Polyester-epoxy paint (do not use mildew-resistant paint indoors, espe-

cially on cribs, playpens or toys because it contains an ingredient that is

toxic)

♦ Stone, slate or cast stone (with waterproof mortar)

♦ Mastic, silicone or polyurethane formed-in-place flooring. Styrofoam in-

sulation

♦ Water-resistant glue

♦ Pressure treated (.40 CCA minimum) or naturally decay resistant lumber,

marine grade plywood

Figure 5-14: Flood-resistant materials

For further details on flood-resistant material requirements, refer to FEMA

Technical Bulletin 2-93, Flood-Resistant Materials Requirements for Buildings

Located in Special Flood Hazard Areas.

ACCESSORY STRUCTURES

Certain accessory structures may not qualify as “buildings.” For example,

open structures, such as carports, gazebos and picnic pavilions that do not have at

least two rigid walls, are not “buildings” and do not have to be elevated or flood-

proofed.

In some cases, low-cost accessory buildings may be wet-floodproofed and do

not have to be elevated or dry floodproofed. These structures could include de-

tached garages and small boathouses, pole barns and storage sheds. Such struc-

tures must meet these requirements:

♦ The owner must obtain a variance (contact your FEMA Regional Office

on procedures for this type of variance),

♦ The building must be used only for parking or storage,

NFIP Requirements 5-44

♦ The building must have the required openings to allow floodwaters in and

out,

♦ The building must be constructed using flood resistant materials below the

BFE,

♦ The building must be adequately anchored to resist floatation, collapse,

and lateral movement, and

♦ All building utility equipment including electrical and heating must be

elevated or floodproofed.

Wet floodproofing involves using flood-resistant materials below the BFE and

elevating things subject to flood damage above the BFE. Items that should be in-

stalled above the BFE include electrical boxes, switches and outlets. Only the

minimum amount of electrical equipment required by code may be located below

the BFE, and that equipment must be flood damage resistant.

For additional guidance, see Wet Floodproofing Requirements, FIA-TB-7,

FEMA 1994, and Engineering Principles and Practices for Flood Damage-

Resistant Building Support Utility Systems.

MANUFACTURED HOMES

44 CFR 59.1 Definitions: "Manufactured home" means a structure, transportable

in one or more sections, which is built on a permanent chassis and is designed

for use with or without a permanent foundation when attached to the required

utilities. The term "manufactured home" does not include a "recreational vehicle".

Manufactured homes include not only manufactured homes that meet HUD

manufactured home standards, but also older mobile homes that pre-date these

standards.

Elevation

Generally, manufactured homes must meet the same flood protection require-

ment as “stick built” or conventional housing. Since they are usually residential

buildings, they must be elevated so the lowest floor is above the BFE.

NFIP Requirements 5-45

44 CFR 59.1 Definitions: "Manufactured home park or subdivision" means a par-

cel (or contiguous parcels) of land divided into two or more manufactured home

lots for rent or sale.

44 CFR 59.1 Definitions: “Existing manufactured home park or subdivision”

means a manufactured home park or subdivision for which the construction of fa-

cilities for servicing the lots on which the manufactured homes are to be affixed

(including, at a minimum, the installation of utilities, the construction of streets,

and either final site grading or the pouring of concrete pads) is completed before

the effective date of the floodplain management regulations adopted by the

community.

44 CFR 60.3(c)(6) Require that manufactured homes placed or substantially im-

proved within Zones A1-30, AH, and AE on the communities FIRM on sites (i)

Outside of a manufactured home park or subdivision, (ii) In a new manufactured

home park or subdivision, (iii) In an expansion to an existing manufactured home

park or subdivision, or (iv) In an existing manufactured home or subdivision on

which a manufactured home has sustained “substantial damage” as the result of

a flood, be elevated on a permanent foundation such the lowest floor of the

manufactured home is elevated to or above the base flood elevation and be se-

curely anchored to an adequately anchored foundation system to resist floatation

collapse and lateral movement.

44 CFR 60.3(c)(12) Require that manufactured homes to be placed or substan-

tially improved on sites in an existing manufactured home park or subdivision

within Zones A-1-30, AH, and AE on the community's FIRM that are not subject

to the provisions of paragraph (c)(6) of this section be elevated so that either (I)

the lowest floor of the manufactured home is at or above the base flood eleva-

tion, or (ii) the manufactured home chassis is supported by reinforced piers or

other foundation elements of at least equivalent strength that are no less than 36

inches in height above grade and be securely anchored to an adequately an-

chored foundation system to resist floatation, collapse, and lateral movement.

44 CFR Section 60.3(c)(6) establishes the basic elevation and anchoring re-

quirements that apply to most manufactured home placements including those

outside of manufactured home parks and subdivision and in new manufactured

home parks and subdivisions. These manufactured homes must have their lowest

floors at or above the BFE. These requirements also apply to manufactured

homes placed in expansions to existing manufactured home parks and on sites

where manufactured homes are substantially damaged by a flood. As with stick-

built housing, all parts of the manufactured home below the BFE must be con-

structed with flood resistant materials and building utility systems must either be

elevated or made watertight to the BFE. The best way to meet this requirement is

to elevate the bottom of the manufactured home chassis to this elevation. See

FEMA’s Manufactured Home Installation in Flood Hazard Areas, FEMA-85, for

additional guidance

44 CFR Section 60.3(c)(12) allows for a limited exemption to elevating to the

BFE for sites in existing manufactured housing (mobile home) parks. These older

NFIP Requirements 5-46

manufactured home parks were established before Flood Insurance Rate Maps

(FIRMs) were issued for the community and before the community adopted a

floodplain management ordinance that meets NFIP requirements. In such older

parks, a newly placed manufactured home chassis must be “supported by rein-

forced piers or other foundation elements of at least equivalent strength that are

no less than 36 inches in height above grade.”

This exemption does not apply to repairing or replacing a manufactured home

on a site in an existing manufactured home park where a manufactured home has

been substantially damaged by a flood.

This exemption is a compromise that tries to balance the flood hazard against

the severe economic impacts on some manufactured home park owners that

would result if elevation to the BFE were required. There are often practical diffi-

culties in elevating manufactured homes to the BFE in many of the older parks

due to small lot sizes and the split ownership of the manufactured home and the

lot itself. The exemption may not be necessary or appropriate for your commu-

nity, especially if manufactured home parks are able to meet the requirement to

elevate to the BFE. In other areas, the flood hazard may be so severe that the ex-

emption may put lives and property at too great a risk. Many states have not in-

cluded this exemption in their model ordinances and it may not be in your regula-

tions.

Anchoring

44 CFR 60.3(c)(6) …[Manufactured homes must] be elevated on a permanent

foundation … and be securely anchored to an adequately anchored foundation

system to resist flotation, collapse and lateral movement.

A “permanent foundation” means more than a stack of concrete blocks. It

should include a below-grade footing capable of resisting overturning, the depth

needs to account for frost depth and expected scour, the footing must be sized ap-

propriately for the site’s soil bearing capacity, and the design needs to account for

seismic and other hazards.

The following types of permanent foundations can be used:

♦ Reinforced piers,

♦ Post-tensioned piers

♦ Posts,

♦ Piles,

♦ Poured concrete walls,

♦ Reinforced block walls, or

♦ Compacted fill.

NFIP Requirements 5-47

“Adequately anchored” means a system of ties, anchors and anchoring equip-

ment that will withstand flood and wind forces. The system must work in satu-

rated soil conditions. Usually this means over-the-top or frame tie-downs in addi-

tion to standard connections to the foundation.

Most states have manufactured home tie-down regulations. Check with your

state NFIP coordinator to see if your state’s regulations also meet the NFIP an-

choring standard. If so, you need only make sure that the state requirement is met

for each new manufactured home installed in your floodplain.

If not, see FEMA’s Manufactured Home Installation in Flood Hazard Areas,

FEMA-85, for additional guidance on anchoring. The anchoring requirement

does apply in an existing (pre-FIRM) manufactured housing or mobile home park.

Even if the manufactured home is not elevated above the BFE, the anchoring sys-

tem must still withstand the forces of a flood over the first floor.

Evacuation: In some areas, there is adequate warning time to remove a manu-

factured home from harm’s way. Protecting such property should not be discour-

aged, so FEMA allows an evacuated manufactured home to be put back on the

original site in an existing manufactured home park without having to meet the

requirements for siting a new manufactured home. Since much can go wrong in

trying to evacuate a manufactured home, evacuation is not a substitute for perma-

nently protecting the manufactured home by elevating it to or above the BFE.

RECREATIONAL VEHICLES

44 CFR 59.1 Definitions: "Recreational vehicle" means a vehicle which is:

(a) built on a single chassis;

(b) 400 square feet or less when measured at the largest horizontal projection;

and

(d) designed primarily not for use as a permanent dwelling but as temporary liv-

ing quarters for recreational, camping, travel, or seasonal use.

A recreational vehicle placed on a site in an SFHA must:

♦ Meet the elevation and anchoring requirements for manufactured homes,

♦ Be on the site for fewer than 180 consecutive days, OR

♦ Be fully licensed and ready for highway use. “Ready for highway use”

means that it is on its wheels or jacking system is attached to the site only

by quick disconnect type utilities and has no permanently attached addi-

tions.

NFIP Requirements 5-48

The purpose of this requirement is to prevent recreational vehicles from being

permanently placed in the floodplain unless they are as well protected from flood-

ing as a manufactured home.

The NFIP does not have minimum requirements for recreational vehicle parks

or campgrounds other than the limitations on the placement of recreational vehi-

cles. Recreational vehicle parks and campgrounds are often good uses for flood-

plains, particularly when flooding usually occurs during seasons when these fa-

cilities are not in use or where there is plenty of warning time prior to a flood.

These facilities should not be permitted in flash flood areas since there may be

loss of life if flooding occurs as well as loss of the recreational vehicles.

AO AND AH ZONES

AO Zones are shallow flooding areas where FEMA provides a base flood

depth. Since there is no BFE, the rules read a little differently.

All new construction and substantial improvements of residential structures

shall have the lowest floor (including basement) elevated above the highest adja-

cent grade:

♦ At least as high as the depth number specified in feet on the community's

FIRM, or

♦ At least two feet if no depth number is specified.

All new construction or substantial improvements of nonresidential structures

shall meet the above requirements or, together with attendant utility and sanitary

facilities, be floodproofed to the same elevation.

AH Zones are also shallow flooding areas, but have BFEs. Buildings in AH

zones must meet the same requirements as in AE zones.

In AO and AH Zones, adequate drainage paths are required around structures

on slopes to guide floodwater around and away from proposed structures. (Re-

quiring this throughout the community is a good idea, as it will prevent local

drainage problems from causing surface flooding.)

A99 AND AR ZONES

An A99 Zone is an SFHA that will be protected by a Federal flood control

project that is currently under construction and which meets specified conditions.

An AR Zone is an SFHA that used to be a B, C or X Zone that used to be pro-

tected by an accredited flood control system. The system has been decertified but

is in the process of being restored to provide protection to the base flood level.

NFIP Requirements 5-49

When the flood control systems are completed or restored, the areas in A99

and AR Zones are expected to be remapped and taken out of the SFHA. Until

then, they are treated as SFHA for insurance purposes and there are some flood-

plain management requirements.

A99 and AR Zones are special situations—few exist. If you have one, you

should contact your state NFIP coordinating agency or FEMA Regional Office for

guidance on regulatory requirements for you situation.

NFIP Requirements 5-50

F. NEW BUILDINGS IN V ZONES

Zones V1-30, VE and/or V identified on FIRMs designate high hazard areas

along coastlines that are subject to flooding from storm surge and wave impacts

during coastal storms and hurricanes. Different construction standards apply in

V-zones to help buildings withstand these wave impacts. See Unit 3 for informa-

tion on how V-zones are designated. Many V Zones are also subject to erosion

and scour which can undercut building foundations.

Basic rule #5: Due to wave impacts, V Zones have special building protec-

tion standards in addition to the requirements for A Zones.

This section identifies only those building protection requirements that differ

from the A Zone criteria. Unless mentioned in this section, all A Zone standards

apply for new and substantially improved buildings in V Zones. If your commu-

nity contains V-zones, you will need more information than is contained in this

section to adequately regulate coastal construction. You should obtain a copy of

FEMA’s Coastal Construction Manual, FEMA-55 (May 2000) and, if possible,

attend a course on coastal construction offered by FEMA, your state, or a building

code organization.

BUILDING LOCATION

New or substantially improved buildings in V Zones must be located land-

ward of the reach of mean high tide. They cannot be built over water. In fact, it’s

best to be as far back from the shore as possible in order to avoid the more dan-

gerous areas subject to waves and erosion. The ability of a building to withstand

wave impacts increases the farther it is set back from the shore.

Avoid areas of sand dunes and mangroves. Human alteration of sand dunes

and mangrove stands within V Zones is prohibited unless it can be demonstrated

that such alterations will not increase potential flood damage.

Both of these natural features are protected against alteration because they are

important first lines of defense against coastal storms and can do much to reduce

losses to inland coastal development.

Generally, you can assume that any removal or other alteration of a sand dune

will increase flood damage. The burden should be placed on the permit applicant

to demonstrate that this will not occur. This will require a report by a coastal en-

gineer or geologist.

ELEVATION ON PILES OR COLUMNS

All new construction and substantial improvements to buildings in V Zones

must be elevated on pilings, posts, piers or columns.

NFIP Requirements 5-51

44 CFR 60.3(e)(4) [The community must] Provide that all new construction and

substantial improvements in Zones V1-30 and VE, and also Zone V if base flood

elevation data is available, on the community's FIRM, are elevated on pilings and

columns so that (i) the bottom of the lowest horizontal structural member of the

lowest floor (excluding the pilings or columns) is elevated to or above the base

flood level…

Other methods of elevating buildings —on fill, solid walls or crawlspaces—

and floodproofing are prohibited because these techniques present obstructions to

wave action. The force of a breaking wave is so great that these types of founda-

tions would be severely damaged, resulting in collapse of the building. Waves

can also ramp up on fill and reach the elevated portions of the building.

Construction on piles or columns allows waves to pass under the building

without transmitting the full force of the waves to the building’s foundation. A

special case is made for installing breakaway walls between the pilings or col-

umns, but such walls are not supporting foundation walls.

While fill is not allowed for structural support for buildings within V Zones

because of the severe erosion potential of such locations, limited fill is allowed for

landscaping, local drainage needs, and to smooth out a site for an unreinforced

concrete pad. However, this fill cannot in any way obstruct the flow of water un-

der the building.

How high? Within V

Zones, the controlling eleva-

tion is the bottom of the low-

est horizontal structural

member of the lowest floor.

(In comparison, within A

Zones, the controlling eleva-

tion is the top of the lowest

floor.) This is to keep the

entire building above the an-

ticipated breaking wave

height of a base flood storm

surge.

Figure 5-15: In V Zones, the lowest floor is

measured from the bottom of the lowest

horizontal structural member

Wind and water loads

The design of the supporting foundation must account for wind loads in com-

bination with the forces that accompany the base flood. Cross bracing and proper

connections are key to doing this.

NFIP Requirements 5-52

44 CFR 60.3(e)(4) …(ii) [The community must ensure that] the pile or column

foundation and structure attached thereto is anchored to resist flotation, collapse

and lateral movement due to the effects of wind and water loads acting simulta-

neously on all building components. Water loading values used shall be those

associated with the base flood. Wind loading values used shall be those required

by applicable State or local building standards. A registered professional engi-

neer or architect shall develop or review the structural design, specifications and

plans for the construction, and shall certify that the design and methods of con-

struction to be used are in accordance with accepted standards of practice for

meeting the provisions of (e)(4)(i) and (ii) of this section.

Piles made of wood, steel, or pre-cast concrete are preferred over block col-

umns and similar foundations that are less resistant to lateral forces. Pilings are

necessary in areas subject to erosion and scour, but it is critical that they be em-

bedded deep enough (Figure 5-16).

Figure 5-16: Piles must be embedded well below the scour depth

NFIP Requirements 5-53

Figure 5-17: This house had inadequate

pile embedment and cross bracing

Certification

Designing and constructing a V-zone building requires the involvement of a

design professional to ensure that the building will withstand the combined forces

of wind and wave impact. A registered professional engineer or architect must

develop or review the structural design, specifications and plans for the construc-

tion, and certify that the design and planned methods of construction are in accor-

dance with accepted standards of practice for meeting the above provisions.

You must maintain a copy of the engineer’s or architect’s certification in the

permit file for all structures built or substantially improved in the V Zone.

The North Carolina Division of Emergency Management has prepared a V-

Zone certification form (Figure 5-18) to ensure that these requirements are met.

This is provided as an example. Check with your state NFIP coordinator to see if

your state has developed a V Zone certification form.

BREAKAWAY WALLS

The preferred method of constructing a V-zone building is to leave the area

below the elevated floor free of obstruction or to enclose the area only with lat-

ticework or insect screening. That way waves can freely flow under the building

without placing additional loads on the foundation. The only solid walls allowed

below the lowest floor in a building in a V Zone are breakaway walls that will

give way under wind and water loads without causing collapse, displacement or

other damage to the elevated portion of the building or the supporting pilings or

columns. Just as in A Zones, this space enclosed by these walls is to be used

NFIP Requirements 5-54

solely for parking of vehicles, building access or storage, and must be constructed

of flood-resistant material.

Figure 5-18: Sample V Zone certification

NFIP Requirements 5-55

44 CFR 60.3(e)(5) [The community must] Provide that all new construction and

substantial improvements within Zones V1-30, VE, and V on the community's

FIRM have the space below the lowest floor either free of obstruction or con-

structed with non-supporting breakaway walls, open wood lattice-work, or insect

screening intended to collapse under wind and water loads without causing col-

lapse, displacement, or other structural damage to the elevated portion of the

building or supporting foundation system. For the purposes of this section, a

breakaway wall shall have a design safe loading resistance of not less than 10

and no more than 20 pounds per square foot. Use of breakaway walls which ex-

ceed a design safe loading resistance of 20 pounds per square foot (either by

design or when so required by local or State codes) may be permitted only if a

registered professional engineer or architect certifies that the designs proposed

meet the following conditions:…

Solid breakaway walls are allowed, as are garage doors that meet the same

breakaway requirements. Solid breakaway walls are intended to collapse under

the force of wave impacts without damaging the buildings foundation or the ele-

vated portion of the building. All solid breakaway walls should have their designs

certified by a registered professional engineer or architect. This can be done as

part of the anchoring certification discussed earlier in this section.

The area enclosed by solid breakaway walls should be limited to less than 300

square feet because:

♦ Flood insurance rates increase dramatically for enclosures larger than 300

square feet.

♦ Larger areas encourage conversion to habitable living areas, which are dif-

ficult to detect and enforce as violations and which can sustain significant

damage during a storm.

COASTAL AE ZONES

NFIP regulations apply the same minimum requirements to both coastal AE

zones and riverine AE zones. FEMA has concluded that these standards may not

provide adequate protection in coastal AE zones subject to wave effects, velocity

flows, erosion, scour, or combinations of these forces. Wave tank studies have

shown that breaking waves considerably less than the 3-foot criteria used to des-

ignate VE zones can cause considerable damage.

FEMA’s Coastal Construction Manual, FEMA-55 (May 2000) and other re-

cent FEMA publications have introduced the concept of Coastal AE Zone to en-

courage use of V-zone construction methods and standards in these areas. For

example, pile or column or other open foundations are more likely to withstand

wave impacts than other types of foundations. If your community contains

Coastal AE Zones, you are encouraged to revise your ordinances to apply all or

some of the VE zone standards to these areas.

NFIP Requirements 5-56

G. OTHER REQUIREMENTS

The primary thrust of the NFIP regulations is to protect insurable buildings

and reduce future exposure to flood hazards. However, there are some additional

requirements that help ensure that the buildings stay habitable and additional

flood problems are not created.

SUBDIVISIONS

As noted in Section B of this unit, once you obtain base flood elevations for a

subdivision or other large development, new buildings must be properly elevated

or floodproofed. These subdivisions and developments must also be reviewed to

ensure they are reasonably safe from flood damage.

44 CFR 60.3(a)(4) [The community must] Review subdivision proposals and

other proposed new development including manufactured home parks or subdi-

visions, to determine whether such proposals will be reasonably safe from flood-

ing. If a subdivision proposal or other proposed new development is in a flood-

prone area, any such proposals shall be reviewed to assure that (i) all such pro-

posals are consistent with the need to minimize flood damage within the flood-

prone area, (ii) all public utilities and facilities, such as sewer, gas, electrical, and

water systems are located and constructed to minimize or eliminate flood dam-

age, and (iii) adequate drainage is provided to reduce exposure to flood hazards;

This review applies to subdivisions and other development, such as apart-

ments, parks, shopping centers, schools and other projects.

If a site is floodprone, the builder should:

♦ Minimize flood damage by locating structures on the highest natural-

ground.

♦ Have public utilities and facilities located and constructed so as to mini-

mize flood damage.

♦ Provide adequate drainage for each building site.

The site plans of new development and proposed plats for subdivisions can

usually be designed to minimize the potential for flood damage while still achiev-

ing the economic goals of the project. For example, lot size could be reduced and

the lots clustered on high ground, with building sites having views of the flood-

plain. See Unit 6 for ideas on how subdivisions can be designed to minimize

flood damages.

NFIP Requirements 5-57

WATER AND SEWER SYSTEMS

44 CFR 60.3(a)(5) [The community must] Require within flood-prone areas new

and replacement water supply systems to be designed to minimize or eliminate

infiltration of flood waters into the systems; and

44 CFR 60.3(a)(6) [The community must] Require within flood-prone areas (i)

new and replacement sanitary sewage systems to be designed to minimize or

eliminate infiltration of flood waters into the systems and discharges from the sys-

tems into flood waters and (ii) onsite waste disposal systems to be located to

avoid impairment to them or contamination from them during flooding.

The objective of these requirements is to ensure that a building that is pro-

tected from flood damage can still be used after the flood recedes.

In most instances, these criteria can be met through careful system design.

Manholes should be raised above the 100-year flood level or equipped with seals

to prevent leakage. Pumping stations should have electrical panels elevated above

the BFE.

On-site waste disposal systems should be located to ensure they will not re-

lease contamination in a flood and can be used after flood waters recede. The first

objective should be to locate the system outside the flood hazard area, if that is

feasible. At a minimum, an automatic backflow valve should be installed to pre-

vent sewage from backing up into the building during flooding.

WATERCOURSE ALTERATIONS

44 CFR 60.3(b)(6) [The community must] Notify, in riverine situations, adjacent

communities and the State Coordinating Office prior to any alteration or reloca-

tion of a watercourse, and submit copies of such notifications to the [Federal In-

surance] Administrator;

The community must notify adjacent communities and the appropriate state

agency prior to altering or relocating any river or stream within its jurisdiction.

Copies of such notifications must be submitted to the FEMA Regional Office.

44 CFR 60.3(b)(7) [The community must] Assure that the flood carrying capacity

within the altered or relocated portion of any watercourse is maintained;

Any alteration or relocation of a watercourse should not increase the commu-

nity's flood risks or those of any adjacent community. This could happen if the

watercourse's capacity to carry flood flow is reduced because a smaller or less-

efficient channel is created, or by modifications to the floodway as a result of the

project. You must ensure that the altered or relocated channel has at least the ca-

pacity of the old channel. For any significant alteration or relocation, you should

consider requiring the applicant to have an engineer certify that the flood-flow

NFIP Requirements 5-58

carrying capacity is maintained and that there will be no increase in flood flows

downstream.

After altering a watercourse, the developer has created an artificial situation

and must assume responsibility for maintaining the capacity of the modified

channel in the future. Otherwise, flooding is likely to increase as the channel silts

in, meanders or tries to go back to its old location.

Federal and state permits may be required for any alteration or relocation ac-

tivity. It is recommended that the community require the submittal and approval

of a CLOMR from FEMA for large-scale proposals (see CLOMR procedures dis-

cussion in Unit 4, Section D).

NFIP Requirements 5-59