Free-of-Obstruction

Requirements

For Buildings Located in Coastal High Hazard Areas 

in Accordance with the National Flood Insurance 

Program

NFIP Technical Bulletin 5 / March 2020
Comments on the Technical Bulletins should be directed to:

DHS/FEMA

Federal Insurance and Mitigation Administration (FIMA) Risk Management Directorate 

Building Science Branch 

400 C Street, S.W., Sixth Floor

Washington, DC 20472-3020

NFIP Technical Bulletin 5 (2020) replaces NFIP Technical Bulletin 5 (2008), Free-of-Obstruction 

Requirements.

Cover photograph: Area beneath an elevated building that is free of obstruction.

NFIP Technical Bulletin 5 contains information that is proprietary to and copyrighted by the American 

Society of Civil Engineers and information that is proprietary to and copyrighted by the International Code 

Council, Inc. All information is used with permission.

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NFIP TECHNICAL BULLETIN 5 MARCH 2020 i

Table of Contents

Acronyms.............................................................................................................................................................iv

1 Introduction .....................................................................................................................................................1

2 National Flood Insurance Program Regulations ..............................................................................................3

3 Building Codes and Standards ........................................................................................................................6

3.1 International Residential Code.............................................................................................................7

3.2 International Building Code and ASCE 24..........................................................................................9

4 NFIP Flood Insurance Implications ................................................................................................................13

5 Free-of-Obstruction Requirement Considerations ........................................................................................ 14

6 Building Elements Below the Base Flood Elevation.......................................................................................15

6.1 Access Stairs and Ramps......................................................................................................................15

6.2 Decks, Porches, and Patios ..................................................................................................................18

6.3 Elevators................................................................................................................................................19

6.4 Enclosed Areas .....................................................................................................................................19

6.5 Mechanical, Electrical, and Plumbing Equipment, Ducts, Tanks, and Fixtures .............................26

6.6 Foundation Bracing .............................................................................................................................28

6.7 Grade Beams ........................................................................................................................................30

6.8 Shear Walls ...........................................................................................................................................30

6.9 Slabs ......................................................................................................................................................32

7 Site Development: Practices and Issues .......................................................................................................35

7.1 Accessory Storage Structures...............................................................................................................35

7.2 Detached Garages................................................................................................................................36

7.3 Erosion Control Structures..................................................................................................................37

7.4 Fences and Privacy Walls .....................................................................................................................38

7.5 Fill..........................................................................................................................................................39

7.6 Ground Elevations At or Above the Base Flood Elevation................................................................43

7.7 On-Site Septic Systems.........................................................................................................................43

7.8 Restroom Buildings and Comfort Stations ........................................................................................44

7.9 Swimming Pools and Spas...................................................................................................................44

8 References ....................................................................................................................................................46
ii NFIP TECHNICAL BULLETIN 5 MARCH 2020

List of Figures

Figure 1: Damage to an elevated building as a result of stairs that not break away cleanly .....................16

Figure 2: Open stairs, which minimize transfer of flood and wave forces................................................. 17

Figure 3: Massive stairs attached to an elevated coastal home, which act as an obstruction.................... 17

Figure 4: Compliant wood slats installed flat against foundation pilings..................................................21

Figure 5: Compliant, fixed, wood louvers installed between pilings..........................................................21

Figure 6: Determination of the percentage of open area for a lattice or louver wall................................22

Figure 7: Breakaway wall that did not break away, which led to wave runup and contributed to 

flood damage on the side of the elevated building.....................................................................22

Figure 8: Above-grade enclosure ..................................................................................................................23

Figure 9: Above-grade enclosure floor system attached to building foundation ......................................24

Figure 10: Above-grade enclosure supported by independent foundation .................................................24

Figure 11: Two-level enclosure........................................................................................................................25

Figure 12: Two-level enclosure schematic ......................................................................................................26

Figure 13: Utilities mounted on wall, which prevented the wall from breaking away cleanly....................27

Figure 14: Floating debris trapped by metal rod cross bracing....................................................................29

Figure 15: Knee bracing..................................................................................................................................29

Figure 16: Cross bracing that interfered with the failure of a breakaway wall............................................29

Figure 17: Grade beams that were exposed to flood forces during hurricane-induced scour; 

grade beams must resist flood, wave, and debris loads when undermined ...............................30

Figure 18: High-rise buildings elevated on shore-perpendicular shear walls..............................................31

Figure 19: Failure of a shore-perpendicular solid foundation wall that supported a low-rise 

building, which resulted in failure of the beam and floor system that were supported 

by the shore-perpendicular wall ...................................................................................................32

Figure 20: Damage to building foundation caused in part by failure of the reinforced slab 

undermined by erosion .................................................................................................................33

Figure 21: Unreinforced slab that broke apart without imposing loads on the foundation.......................33

Figure 22: Example of frangible slab design..................................................................................................34

Figure 23: Small accessory structure that was moved by flood and wind forces .........................................36

Figure 24: Wave runup and overtopping at an erosion control structure....................................................37

Figure 25: Shore-parallel timbers attached to a pile foundation that were intended to act as a 

bulkhead but constituted an obstruction and are not permitted...............................................38

Figure 26: Shore-perpendicular reinforced masonry privacy wall that collapsed into the 

foundation of an adjacent building and contributed to failure of the corner 

foundation piling and pile cap/beam..........................................................................................39
NFIP TECHNICAL BULLETIN 5 MARCH 2020 iii

List of Tables

Table 1: Comparison of Selected 2018 IRC Requirements and NFIP Requirements........................................ 7

Table 2: Comparison of Selected 2018 IBC and ASCE 24-14 Requirements with 

NFIP Requirements .............................................................................................................................10

Revision History

April 2020 Added 44 CFR citation for swimming pools and spas topic in Table 1 (page 8)

April 2020 Corrected caption for Figure 1 (page 16)

Figure 27: Post-hurricane photo showing an elevated building surrounded by gently sloping fill and an 

adjacent, damaged, older, non-elevated building.................................................................................41

Figure 28: Failure of two piles supporting an elevated deck that was likely caused by movement of a spa ......... 45
iv NFIP TECHNICAL BULLETIN 5 MARCH 2020

Acronyms

ASCE American Society of Civil Engineers

BFE base flood elevation

CFR Code of Federal Regulations

DFE design flood elevation

DHS Department of Homeland Security

FEMA Federal Emergency Management Agency

FIRM Flood Insurance Rate Map

IBC International Building Code®

ICC International Code Council®

I-Codes International Codes®

IRC International Residential Code®

ISPSC International Swimming Pool and Spa Code®

NFIP National Flood Insurance Program

PFD primary frontal dune

SEI Structural Engineering Institute

SFHA Special Flood Hazard Area
NFIP TECHNICAL BULLETIN 5 MARCH 2020 1

1 Introduction

This Technical Bulletin provides guidance on the 

National Flood Insurance Program (NFIP) free-ofobstruction requirements in Coastal High Hazard 

Areas, which are designated as Zone V (V, VE, V1-30, 

and/or VO) on a community’s Flood Insurance Rate 

Map (FIRM), as well as the NFIP requirements for 

construction in Zone V to minimize flood damage 

potential that is applicable to construction in Zone V. 

The free-of-obstruction requirements were instituted 

to minimize the transfer of flood forces to an elevated 

building’s foundation and also to minimize the diversion 

or deflection of floodwater or waves that could damage 

the elevated building or neighboring buildings.

This Technical Bulletin also discusses how the presence 

or absence of obstructions can affect NFIP flood 

insurance premiums.

Coastal waves and flooding can exert strong 

hydrodynamic forces on building elements in their 

path. Therefore, the NFIP requires that all new and 

Substantially Improved structures in Coastal High 

Hazard Areas (Zone V) be elevated on pilings or columns with the bottom of the lowest horizontal 

structural members of the lowest floor elevated to or above the base flood elevation (BFE). These open 

foundations allow floodwater and waves to pass beneath the elevated structure.

NFIP TECHNICAL BULLETIN 0

NFIP Technical Bulletin 0, User’s Guide 

to Technical Bulletins, should be used 

as a reference in conjunction with this 

Technical Bulletin. Technical Bulletin 0 

describes the purpose and use of the 

Technical Bulletins, includes common 

concepts and terms, lists useful 

resources, and includes a crosswalk 

of the sections of the NFIP regulations 

identifying the Technical Bulletin that 

addresses each section of the regulations 

and a subject index.

Readers are cautioned that the definitions 

of some of the terms that are used in 

the Technical Bulletins are not the same 

when used by the NFIP for the purpose of 

rating flood insurance policies.

EFFECTS OF OBSTRUCTIONS

The NFIP requires the area beneath elevated structures in Zone V to remain free of any obstructions that 

would prevent the free flow of coastal floodwater and waves during a base flood event. An area beneath a 

structure elevated on an open foundation is considered to be free of obstructions if flood flow and waves 

can pass through the area without significant flow diversion, wave reflection, or wave runup.

• Flow diversion. Change in the course of flood flow when it encounters an object or structure.

Diversion can be accompanied by an increase in the local flood level and/or flood velocity when the

blockage is large relative to the area through which the flow would otherwise pass.

• Wave reflection. Return or redirection of a wave striking an object.

• Wave runup. Rush of water up a slope or structure following wave breaking.

Some flow diversion, wave reflection, and wave runup can occur even with open foundations, but if the 

guidance in this Technical Bulletin is followed, the effects should be minimized during flood conditions up 

to the base flood event.
2 NFIP TECHNICAL BULLETIN 5 MARCH 2020

Any element constructed below the BFE that is attached to a building in Zone V is considered part of the 

building and must meet the free-of-obstruction requirements.

Standard solid foundation walls, such as masonry, concrete, and wood-frame walls, are not permitted 

in Zone V because they would obstruct flow and be at risk of damage from high-velocity flood forces. 

In addition, solid foundations and other obstructions could cause wave runup or reflection or divert 

floodwater into the elevated portion of the building or nearby buildings.

The NFIP interprets the free-of-obstruction requirements to apply to certain site development practices 

that prevent the free flow of coastal floodwater and waves under or around buildings or increase flood 

loads on nearby buildings. Construction elements outside the perimeter (footprint) of and not attached 

to a coastal building (e.g., bulkheads, retaining walls, decks, swimming pools, accessory structures) and 

site development practices (e.g., addition of fill) may alter the physical characteristics of flooding or 

significantly increase wave or flood forces affecting nearby buildings. As part of the design certification 

process for a building in Zone V, the registered design professional must consider the effects these 

elements and practices will have on the building and on nearby buildings.

The NFIP requires buildings to be constructed using methods and materials that minimize the potential 

for flood damage. Therefore, any construction element placed on a building site in Zone V (see Sections 

6 and 7) has the potential to affect the building and nearby buildings, which must be taken into account. 

In addition to potential wave and floodwater diversion effects, obstructions can break free and become 

floodborne debris that may strike and damage other buildings.

The building elements and site development issues in regard to obstruction that are discussed in this 

Technical Bulletin include:

Site development: Practices and issues

• Accessory storage structures

• Detached garages

• Erosion control structures

• Fences and privacy walls

• Fill

• Ground elevations at or above the BFE

• On-site septic systems

• Restroom buildings and comfort stations

• Swimming pools and spas

Building elements below the BFE

• Access stairs and ramps

• Decks, porches, and patios

• Elevators

• Enclosed areas

– Below elevated structures

– Above-grade (elevated)

– Two levels

• Equipment and tanks

• Foundation bracing

• Grade beams

• Shear walls

• Slabs
NFIP TECHNICAL BULLETIN 5 MARCH 2020 3

Building elements and site development practices 

that are not specifically prohibited by the NFIP 

may be used as long as they will not adversely affect 

other structures. However, some building elements 

and site development practices may increase 

flood-related loading on the building where those 

practices are proposed. In such cases, the building 

must be designed to withstand the additional 

flood-related loading and the registered design 

professional must provide the required Zone V 

certification for the building.

Questions about free-of-obstruction requirements 

should be directed to the appropriate local 

official, NFIP State Coordinating Office, or 

Federal Emergency Management Agency (FEMA) 

Regional Office.

2 National Flood Insurance Program 

Regulations

An important NFIP objective is protecting buildings constructed in Special Flood Hazard Areas (SFHAs) 

from damage caused by flooding. The SFHA is the land area subject to flooding by the base flood. SFHAs 

are shown on Flood Insurance Rate Maps (FIRMs) prepared by FEMA as Zones A and V. The base flood 

is the flood that has a 1 percent chance of being equaled or exceeded in any given year (commonly called 

the “100-year” flood).

The NFIP floodplain management regulations include minimum building design criteria that apply to:

• New construction

• Work determined to be Substantial Improvements such as improvements, alterations, and additions

• Repair of buildings determined to have incurred Substantial Damage

A defining characteristic of the NFIP regulations applicable in Zone V is the requirement for the lowest 

horizontal structural member of the lowest floor to be elevated to or above the BFE. This requirement 

applies to both residential and non-residential buildings. Furthermore, the area beneath elevated 

structures must be free of obstructions that would prevent the free flow of coastal floodwater and waves 

during a base flood event.

NFIP TERMS USED 

IN THIS TECHNICAL BULLETIN

• Special Flood Hazard Area (SFHA): Area

subject to flooding by the base flood

(1-percent-annual-chance flood) and shown

on FIRMs as Zone A or Zone V.

• Zone A: Flood zones shown on FIRMs as

Zone A, AE, A1-30, AH, AO, A99, and AR.

• Zone V: Flood zones shown on FIRMs as

Zone V, VE, V1-30, and VO.

• Coastal High Hazard Area: Area shown on

FIRMs and other flood hazard maps as Zone 

V, VO, VE, or V1-30.
4 NFIP TECHNICAL BULLETIN 5 MARCH 2020

The NFIP regulations for Zone V construction are codified in Title 44 Code of Federal Regulations 

(44 CFR) Part 60 Criteria for Land Management and Use. Specific to this Technical Bulletin, 

Section 60.3(a)(3) of the NFIP regulations states:

If a proposed building site is in a flood-prone area, all new construction and substantial 

improvements shall ... (iii) be constructed by methods and practices that minimize flood 

damages ...

Section 60.3(e)(4) states that a community shall require (emphasis added):

... that all new construction and substantial improvements in Zones V1 V30, 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; and (ii) 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 simultaneously 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 engineer or architect shall develop 

or review the structural design, specifications and plans for the construction, and shall certify 

that the design and methods of construction to be used are in accordance with accepted 

standards of practice for meeting the provisions of paragraphs (e)(4)(i) and (ii) of this section.

Section 60.3(e)(5) further states that a community shall require (emphasis added):

... that all new construction and substantial improvements within Zones V1-V30, VE, and V 

on the community’s FIRM have the space below the lowest floor either free of obstruction 

or constructed with non-supporting breakaway walls, open wood lattice-work, or insect 

screening intended to collapse under wind and water loads without causing collapse, 

ZONE V CERTIFICATION OF STRUCTURAL DESIGN AND METHODS OF CONSTRUCTION

The NFIP regulations require communities to ensure that construction meets Zone V requirements, 

including the free-of-obstruction requirement. Registered professional engineers or architects must 

develop or review structural designs, specifications, and plans for new construction and Substantial 

Improvements and certify that designs and methods of construction are in accordance with the 

accepted standards of practice. Building engineers and architects should consult with communities 

on their certification requirements before starting design, and communities must obtain and retain 

the certifications.

Satisfying the NFIP free-of-obstruction requirement is part of the certification. Local officials 

should determine that construction and/or site plans show all proposed site improvement elements 

described in this Technical Bulletin. The NFIP requires Zone V certification prior to construction. 

The community must ensure that what is constructed is compliant; some jurisdictions may require 

post-construction certification by the registered design professional.

See Technical Fact Sheet 1.5 in the Home Builder’s Guide to Coastal Construction (FEMA P-499) (2010a) 

for a discussion of Zone V certification requirements.
NFIP TECHNICAL BULLETIN 5 MARCH 2020 5

displacement, or other structural damage to the elevated portion of the building or 

supporting foundation system. For the purpose 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 exceed 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: (i) Breakaway wall collapse shall result from a water load less than 

that which would occur during the base flood; and (ii) The elevated portion of the building 

and supporting foundation system shall not be subject to collapse, displacement, or other 

structural damage due to the effects of wind and water loads acting simultaneously on all 

building components (structural and non-structural). 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. Such enclosed space shall be useable solely for parking of 

vehicles, building access, or storage.

Section 60.3(e)(6) states that a community shall “prohibit the use of fill for structural support of buildings 

within Zones V1-30, VE, and V on the community’s FIRM.”

Section 60.3(e)(7) states that a community shall “prohibit man-made alteration of sand dunes and 

mangrove stands within Zones V1–30, VE, and V on the community’s FIRM which would increase 

potential flood damage.”

For more information on NFIP regulations, refer to the following for:

• Guidance on coastal construction in the Coastal Construction Manual (FEMA P-55) (2011) and in the

Home Builder’s Guide to Coastal Construction (FEMA P-499) (2010a)

• Guidance on design considerations, buildings codes and regulations, and best practices for coastal

communities in Local Officials Guide for Coastal Construction (FEMA P-762) (2009)

• Guidance on the breakaway wall requirements of Section 60.3(e)(5) of the NFIP regulations in NFIP

Technical Bulletin 9, Design and Construction Guidance for Breakaway Walls Below Elevated Buildings

Located in Coastal High Hazard Areas

• Guidance on the requirement that building materials used below the BFE must meet the flood

damage-resistant materials requirement of Section 60.3(a)(3) of the NFIP regulations in NFIP

Technical Bulletin 2, Flood Damage-Resistant Materials Requirements for Buildings Located in Special Flood

Hazard Areas
6 NFIP TECHNICAL BULLETIN 5 MARCH 2020

3 Building Codes and Standards

In addition to complying with the NFIP requirements, 

all new construction, Substantial Improvements, 

and repair of Substantial Damage must comply with 

applicable building codes and standards that have been 

adopted by states and communities.

The International Codes® (I-Codes®), published by 

the International Code Council® (ICC®), are a family 

of codes that includes the International Residential 

Code® (IRC®), International Building Code® 

(IBC®), International Existing Building Code® 

(IEBC®), and codes that govern the installation of 

mechanical, plumbing, fuel gas service, and other 

aspects of building construction. FEMA has deemed 

that the latest published editions of the I-Codes 

meet or exceed NFIP requirements for buildings and 

structures in flood hazard areas. Excerpts of the flood 

I-CODES AND COASTAL A ZONES

The 2018 International Codes (I-Codes) 

treat Coastal A Zones like Zone V if a 

Limit of Moderate Wave Action (LiMWA) 

is delineated on FIRMs. If a community 

designates an area as a Coastal A Zone 

through its building code or floodplain 

management regulations, buildings in that 

area are required to comply with the 

Zone V requirements for foundations, 

including the free-of-obstruction 

requirement, with an exception that 

permits filled stem wall foundations.

Note: Per the I-Codes and ASCE 24-14, 

breakaway walls in the Coastal A Zone and 

Zone V must have flood openings.

NFIP REQUIREMENTS AND HIGHER REGULATORY STANDARDS

State and Local Requirements. State or local requirements that are more restrictive or stringent 

than the minimum requirements of the NFIP take precedence. The Technical Bulletins and other FEMA 

publications provide guidance on the minimum requirements of the NFIP and describe best practices. 

Design professionals, builders, and property owners should contact local officials to determine whether 

more restrictive provisions apply to buildings or sites in question. All other applicable requirements of the 

state or local building codes must also be met for buildings in flood hazard areas.

Substantial Improvement and Substantial Damage. As part of issuing permits, local officials must 

review not only proposals for new construction but also for work on existing buildings to determine 

whether the work constitutes Substantial Improvement or repair of Substantial Damage. If the work is 

determined to constitute Substantial Improvement or repair of Substantial Damage, the buildings must 

be brought into compliance with NFIP requirements for new construction. Some communities modify the 

definitions of Substantial Improvements and/or Substantial Damage to be more restrictive than the NFIP 

minimum requirements. For more information on Substantial Improvement and Substantial Damage, see 

FEMA P-758, Substantial Improvement/Substantial Damage Desk Reference (2010b), and 

FEMA 213, Answers to Questions About Substantially Damaged/Substantially Damaged Buildings (2018a).

Higher Building Elevation Requirements. Some communities require that buildings be elevated above 

the NFIP minimum requirements. The additional elevation is called freeboard. Design professionals, 

builders, and property owners should check with local officials to determine whether a community has 

freeboard requirements. References to building elevations in this Technical Bulletin should be construed 

as references to the community’s elevation requirement in areas where freeboard is required.
NFIP TECHNICAL BULLETIN 5 MARCH 2020 7

IRC COMMENTARY

ICC publishes companion commentary 

for the IRC. Although not regulatory, the 

commentary provides guidance that is 

useful in complying with, interpreting, and 

enforcing the requirements of the code.

provisions of the I-Codes are available on FEMA’s Building Code Resource webpage (https://www.fema.

gov/building-code-resources).

3.1 International Residential Code

The IRC applies to one- and two-family dwellings and 

townhomes not more than three stories above grade 

plane. The IRC’s free-of-obstruction requirements 

are summarized in Table 1 and compared to NFIP 

requirements.

Table 1 refers to selected requirements of the 2018 IRC 

and notes changes from the 2015 and 2012 editions.

Table 1: Comparison of Selected 2018 IRC Requirements and NFIP Requirements

Topic

Summary of Selected 2018 IRC Requirements and 

Changes from 2015 and 2012 Editions

Comparison with 

NFIP Requirements

Free of 

obstruction

Section R322.3.3 Foundations.

Requires in Coastal High Hazard Areas (Zone V) and Coastal A Zones that 

areas below elevated buildings be either free of obstructions or constructed 

of breakaway walls. In Coastal A Zones, filled stem wall foundations must be 

designed to resist flood loads, erosion, and scour.

Change from 2015 to 2018 IRC: Changes to subsection numbering due to 

insertion of new subsections expanding requirements for 322.3.4, Concrete 

slabs; R322.3.7, Stairways and ramps; and R322.3.8, Decks and porches.

Change from 2012 to 2015 IRC: Applies Zone V requirements in Coastal A 

Zone, if delineated, with an exception that permits stem wall foundations.

Equivalent to NFIP 

44 CFR §§ 60.3(e)(4) 

and (5), except that 

2018 IRC applies 

in both Zone V and 

Coastal A Zones, 

with an exception 

that permits stem 

wall foundations in 

Coastal A Zones.

Use of fill Section R322.3.2 Elevation requirements [excerpt].

Prohibits the use of fill for structural support in Coastal High Hazard Areas 

(Zone V) and Coastal A Zones, while allowing minor quantities of nonstructural 

fill to be used for drainage and landscaping purposes under and around 

buildings and for support of parking slabs, pool decks, patios, and walkways.

Change from 2015 to 2018 IRC: No change.

Change from 2012 to 2015 IRC: No change.

Equivalent to 

NFIP 44 CFR 

§ 60.3(e)(6), with

more specificity for

use of fill for specific,

nonstructural

purposes.

Enclosed 

areas

Section R322.3.5 Walls below design flood elevation.

In Coastal High Hazard Areas (Zone V) and Coastal A Zones, (1) requires that 

enclosures below elevated buildings be designed to break away under certain 

wind and flood loads without damaging the elevated building or the building 

foundation and (2) prohibits mounting of electrical, mechanical, and plumbing 

system components on breakaway walls or penetration of the breakaway 

walls.

Change from 2015 to 2018 IRC: No change.

Change from 2012 to 2015 IRC: Clarifies that attachment or penetration 

by electrical, mechanical or plumbing systems to breakaway walls is not 

permitted.

Exceeds NFIP 

44 CFR § 60.3(e)(5)

by specifying 

components that are 

not to be mounted 

on or penetrate 

through breakaway 

walls and by requiring 

flood openings in 

breakaway walls.
8 NFIP TECHNICAL BULLETIN 5 MARCH 2020

Topic

Summary of Selected 2018 IRC Requirements and 

Changes from 2015 and 2012 Editions

Comparison with 

NFIP Requirements

Equipment 

and tanks

Section R322.1.6 Protection of mechanical, plumbing, and electrical 

systems.

Requires that new electrical, plumbing, and mechanical system elements, 

along with replacements due to Substantial Improvements, be elevated to the 

design flood elevation (DFE) or if below the DFE, to be designed and installed 

to prevent water from entering or accumulating within the element and be able 

to withstand certain loads and stresses.

Change from 2015 to 2018 IRC: No change.

Change from 2012 to 2015 IRC: No change.

Section R322.3.7 Tanks.

Requires tanks to either be located underground or elevated to the DFE. When 

located underground, tanks must be anchored to resist flotation, collapse, 

and lateral movement during the base flood. If elevated, tanks must be on 

platforms that are cantilevered or knee-braced against the building or on a 

platform with a foundation that resists certain wind and flood loads.

Change from 2015 to 2018 IRC: No change.

Change from 2012 to 2015 IRC: Added requirements for tanks.

Equivalent to 

NFIP 44 CFR 

§ 60.3(a)(3)(iv) but

with more specificity:

components are not

to be mounted on or

penetrate through

breakaway walls and

there are explicit

requirements for

tanks.

Concrete 

slabs

Section R322.3.4 Concrete slabs.

Requires that slabs used for parking, floors of enclosures, landings, decks, 

walkways, patios, and similar uses that are beneath buildings or located such 

that they could be undermined or displaced and could cause damage be 

either (1) structurally independent of foundations and no more than 4 inches 

thick, have no turn-downed edges, have no reinforcing, and have isolation 

joints at pilings and columns and control or construction joints in both 

directions no more than 4 feet apart or (2) self-supporting and will remain 

intact under base flood conditions, taking into account scour and erosion, 

and have building foundations capable of resisting any added loads due to the 

presence of the slabs.

Change from 2015 to 2018 IRC: Moved specifications for slabs from R322.3.3. 

to separate subsection.

Change from 2012 to 2015 IRC: No change.

Exceeds NFIP 

44 CFR § 60.3(e)(5)

by specifying 

requirements for 

concrete slabs.

Swimming 

pools and 

spas

Section R326.1 [Swimming Pools, Spas and Hot Tubs] General.

Requires pools and spas to comply with the International Swimming Pool and 

Spa Code® (ISPSC), which requires compliance with American Society of 

Civil Engineers (ASCE) 24.

Change from 2015 to 2018 IRC: No change.

Change from 2012 to 2015 IRC: Added requirement to comply with the ISPSC.

Exceeds NFIP

44 CFR § 60.3(e)(5)

by specifying 

requirements for 

pools and spas.

Building 

envelope

Section R322.3.6.1 Protection of building envelope.

Requires an exterior door at the top of stairs that provides access to the 

building.

Change from 2015 to 2018 IRC: No change.

Change from 2012 to 2015 IRC: Added requirement for door.

Exceeds NFIP 

44 CFR § 60.3(e)(5) 

by specifying 

requirements for door 

at top of stairway.

Table 1: Comparison of Selected 2018 IRC Requirements and NFIP Requirements (continued)
NFIP TECHNICAL BULLETIN 5 MARCH 2020 9

Topic

Summary of Selected 2018 IRC Requirements and 

Changes from 2015 and 2012 Editions

Comparison with 

NFIP Requirements

Stairways 

and ramps

Section R322.3.7 Stairways and ramps.

Provides four options for stairs and ramps located below the lowest floor 

elevation: (1) open or partially open risers and guards, (2) breakaway, 

(3) retractable, or (4) designed to resist flood loads. In all cases, the area

below stairs and ramps must not be enclosed with walls unless the walls are

designed to break away.

Change from 2015 to 2018 IRC: New section for stairways and ramps 

incorporating language from R322.3.3.

Exceeds NFIP 

44 CFR § 60.3(e)(5)

by specifying 

requirements for 

stairways and ramps.

Decks and 

porches

Section R322.3.8 Decks and porches.

Requires attached decks and porches to meet lowest floor elevation 

requirement and either have compliant foundations or be cantilevered from 

or knee-braced to the building. Self-supporting decks and porches must be 

designed to remain in place or break away and may be below the BFE if not 

enclosed by solid walls (including breakaway walls).

Change from 2015 to 2018 IRC: New section for decks and porches 

incorporating language from R322.3.3.

Exceeds NFIP 

44 CFR § 60.3(e)(5) 

by specifying 

requirements for 

decks and porches.

Elevators 

and 

foundation 

bracing

No explicit provisions; see free-of-obstruction requirement in the first row of 

this table (Table 1).

Meets NFIP 44 CFR 

§ 60.3(e)(5), which

has no specific

requirements.

Used with permission from ICC.

3.2 International Building Code and ASCE 24

The flood provisions of the International Building 

Code® (IBC®) meet or exceed the NFIP requirements 

for buildings largely through reference to the ASCE 24, 

Flood Resistant Design and Construction. The IBC applies to 

all applicable buildings and structures. While primarily 

used for buildings and structures other than dwellings 

within the scope of the IRC, the IBC may be used to 

design dwellings. ASCE 24 applies to structures subject to 

building code requirements. The ASCE 24 requirements, 

summarized in Table 2, are more specific than the NFIP 

free-of-obstruction requirements.

Table 1: Comparison of Selected 2018 IRC Requirements and NFIP Requirements (continued)

IBC AND ASCE COMMENTARIES

ICC publishes companion commentary 

for the IBC, and ASCE publishes 

companion commentary for 

ASCE 24. Although not regulatory, the 

commentaries provide information and 

guidance that are useful in complying 

with, interpreting, and enforcing 

requirements.
10 NFIP TECHNICAL BULLETIN 5 MARCH 2020

Table 2: Comparison of Selected 2018 IBC and ASCE 24-14 Requirements with NFIP Requirements

Topic

Summary of Selected 2018 IBC / ASCE 24-14 Requirements 

and Changes from 2015 and 2012 IBC / ASCE 24-05 

Comparison with NFIP 

Requirements

General 

design 

requirement

2018 IBC Section 1612.2 Design and construction.

Requires design and construction of buildings and structures located in 

Coastal High Hazard Areas (Zone V) and Coastal A Zones to comply with 

Chapter 5 of ASCE 7 and ASCE 24.

Change from 2015 to 2018 IBC: No change except renumbering of section.

Change from 2012 to 2015 IBC: Applies Coastal High Hazard Area 

requirements in Coastal A Zones if delineated.

Exceeds NFIP 44 CFR 

§ 60.3(e) by referring

to ASCE 24, which has

more specificity for some

foundation elements and

higher minimum building

elevations, and which

requires meeting Zone V

design and construction

standards in Coastal A

Zones (which are not

defined in the NFIP).

Obstruction ASCE 24-14 Section 1.2 Definitions.

“Obstruction – Any object or structural component attached to a structure 

below the DFE that can cause an increase in flood elevation, deflect 

floodwaters, or transfer flood loads to any structure.” The DFE in the 

definition of obstruction is the Design Flood Elevation, which will be equal 

to or higher than the BFE.

Change from ASCE 24-05: No change.

The NFIP does not define 

“obstruction.”

Free of 

obstruction

ASCE 24-14 Section 4.5.1 Foundation Requirements, General.

• Applies to foundation systems in Coastal High Hazard Areas (Zone V)

and Coastal A Zones.

• Requires foundations to be designed to minimize forces acting on

foundations, to minimize damage to the foundations and the elevated

structures, and to adequately transfer all loads imposed on the

foundations and elevated structures to the supporting soils.

With the exception of certain bracing and shear walls, requires foundation 

system to be free of obstructions that will restrict or eliminate free passage 

of high-velocity flood waters and waves during design flood conditions.

Change from ASCE 24-05: No change.

Equivalent to NFIP 

44 CFR § 60.3(e)(5). 
NFIP TECHNICAL BULLETIN 5 MARCH 2020 11

Topic

Summary of Selected 2018 IBC / ASCE 24-14 Requirements 

and Changes from 2015 and 2012 IBC / ASCE 24-05 

Comparison with NFIP 

Requirements

Use of fill 2018 IBC Section 1804.5 Grading and fill in flood hazard areas.

Specifies that fill is only allowed where constructed and placed to avoid 

diversion of water and waves toward any building or structure. Where 

allowed, fill is required to be stable under conditions of flooding, including 

rapid rise and drawdown and wave action.

Change from 2015 to 2018 IBC: Clarifies that fill where allowed must be 

stable under conditions of flooding.

Change from 2012 to 2015 IBC: No change.

ASCE 24-14 Section 4.5.4 Use of Fill.

• Specifies that placement of nonstructural fill for minimal site grading and

landscaping and to meet local drainage requirements is permitted.

• Specifies that placement of nonstructural fill under and around a

structure for dune construction or reconstruction is permitted if an

engineering report documents that the fill will not result in wave runup,

ramping, or deflection of floodwaters that can cause damage to

structures.

Change from ASCE 24-05: Clarifies that an engineering report is 

necessary to document the effect of fill, and the commentary clarifies 

that the intent is to allow minor amounts of nonstructural fill for specific 

purposes.

Equivalent to NFIP 

44 CFR § 60.3(e)(6), 

with more specificity for 

use of fill for specific, 

nonstructural purposes.

Enclosed 

areas

ASCE 24-14 Section 4.6 Enclosed Areas Below Design Flood 

Elevation.

Requires enclosed areas below DFE to be designed and constructed 

with breakaway walls, with flood openings in those walls, and requires 

stairways within the enclosed area to have an exterior door at the top of 

the stairs.

Change from ASCE 24-05: Modified to refer to subsections for 

requirements and adds the requirement for an exterior door at the top of 

the stairs.

ASCE 24-14 Section 4.6.1 Breakaway Walls.

Change from ASCE 24-05: No change.

ASCE 24-14 Section 4.6.2 Openings in Breakaway Walls.

Change from ASCE 24-05: Modified to require flood openings in 

breakaway walls forming an enclosure.

Exceeds NFIP 44 CFR 

§ 60.3(e)(5) by requiring

flood openings in

breakaway walls and

a door at the top

of stairways within

enclosures.

Utilities and 

equipment

ASCE 24-14 Section 7.1 General.

Requires attendant utilities and equipment to be at or above specified 

elevations or be specifically designed, constructed, and installed to 

prevent floodwaters from entering or accumulating within components.

Change from ASCE 24-05: No change

Exceeds NFIP 44 CFR 

§ 60.3(a)(3)(iv) with

freeboard requirements

for utility system

platforms and equipment

for most buildings.

Tanks ASCE 24-14 Section 9.7 Tanks.

Requires tanks in Coastal High Hazard Areas (Zone V) and Coastal A Zones 

to be (1) elevated on platforms meeting certain requirements or (2) installed 

and anchored below the eroded ground surface.

Change from ASCE 24-05: Consolidated requirements for tanks in 

Section 9.7.

Exceeds NFIP 44 CFR 

§ 60.3(a)(3)(iv) with

specificity for platforms

and requirements for

tanks.

Table 2: Comparison of Selected 2018 IBC and ASCE 24-14 Requirements with NFIP Requirements (continued)
12 NFIP TECHNICAL BULLETIN 5 MARCH 2020

Topic

Summary of Selected 2018 IBC / ASCE 24-14 Requirements 

and Changes from 2015 and 2012 IBC / ASCE 24-05 

Comparison with NFIP 

Requirements

Slabs ASCE 24-14 Section 9.3 Concrete Slabs.

Requires in Coastal High Hazard Areas (Zone V) and Coastal A Zones 

that concrete slabs be either (1) designed as frangible, not structurally 

connected to structure, and not capable of creating debris that would 

cause significant damage to other structures or (2) be self-supporting and 

remain in place and functional after the design flood.

Change from ASCE 24-05: Slabs were moved from Section 4.8 to Section 

9.3. New text permits (non-building-foundation) self-supporting structural 

slabs for parking/enclosure/deck/patio in Zone V and Coastal A Zone.

Exceeds NFIP 

44 CFR § 60.3(e)(5) 

with requirements for 

concrete slabs.

Swimming 

pools and 

spas

2018 IBC Section 3109.1 General.

Requires, within Coastal High Hazard Areas (Zone V) and Coastal A 

Zones, that the design and construction of swimming pools, spas, and 

hot tubs comply with the ISPSC, which requires pools to be designed in 

accordance with ASCE 24.

Change from 2015 to 2018 IBC: No change

Change from 2012 to 2015 IBC: Replaces specific requirements with 

reference to the ISPSC.

ASCE 24-14 Section 9.6.2 Pools in Coastal High Hazard Areas, 

Coastal A Zones and Other Flood Hazard Areas.

Requires pools to be (1) elevated, (2) designed to break away without 

producing damaging debris, or (3) designed to remain in the ground 

without obstructing flow that could cause damage. Pools must be 

structurally independent of buildings and structures unless located in or 

on elevated floors or roofs that are above the DFE.

Change from ASCE 24-05: Clarifies pool requirements for pools within 

Coastal High Hazard Areas, Coastal A Zones, and other flood hazard 

zones.

Exceeds NFIP 

44 CFR § 60.3(e)(5) 

with requirements for 

swimming pools and 

spas.

Elevators 2018 IBC Section 3001.3 Referenced standards.

Requires the design, construction, installation, alteration, repair, and 

maintenance of elevators and conveying systems and their components 

to comply with the standard specified in 2018 IBC Section 3001.3, 

Table 3001.3, and ASCE 24 unless the code states otherwise.

Change from 2015 to 2018 IBC: Standards moved to Table 3001.3.

Change from 2012 to 2015 IBC: No change.

Exceeds NFIP 

44 CFR § 60.3(e)(5) 

with requirements for 

elevators.

Access 

stairs and 

ramps

ASCE 24-14 Section 8.1 General.

In Coastal High Hazard Areas (Zone V) and Coastal A Zones provides four 

options for the design and construction of stairways and ramps below the 

required elevation.

Change from ASCE 24-05: Adds option for retractable stairways and 

ramps.

Exceeds NFIP 

44 CFR § 60.3(e)(5) 

with requirements and 

alternatives for stairways 

and ramps.

Table 2: Comparison of Selected 2018 IBC and ASCE 24-14 Requirements with NFIP Requirements (continued)
NFIP TECHNICAL BULLETIN 5 MARCH 2020 13

Topic

Summary of Selected 2018 IBC / ASCE 24-14 Requirements 

and Changes from 2015 and 2012 IBC / ASCE 24-05 

Comparison with NFIP 

Requirements

Decks and 

porches

ASCE 24-14 Section 9.2 Decks and Porches

9.2.1 Attached Decks and Porches.

In coastal high hazard areas (Zone V) and Coastal A Zones, specifies 

that attached decks and porches be elevated on certain foundations or 

cantilevered from the main structure.

ASCE 24-14 Section 9.2.2 Detached Decks and Porches.

In Coastal High Hazard Areas (Zone V) and Coastal A Zones, specifies that 

detached decks and porches be (1) designed and constructed to remain 

intact and in place during the base flood or (2) be designed to be frangible, 

minimizing debris capable of causing significant damage to any structure.

Change from ASCE 24-05: Clarifications with no new requirements or 

limitations.

Exceeds NFIP 

44 CFR § 60.3(e)(5) with 

requirements for decks 

and porches.

Foundation 

bracing

ASCE 24-14 Section 4.5.11 Bracing.

Change from ASCE 24-05: No change.

Exceeds NFIP 

44 CFR § 60.3(e)(5) with 

requirements for bracing.

Used with permission from ASCE and ICC.

4 NFIP Flood Insurance Implications

Meeting the minimum NFIP floodplain management 

requirements does not necessarily result in the 

lowest NFIP flood insurance premium. NFIP flood 

insurance premiums depend on the presence, location, 

construction, size, age, and use of enclosures and other 

building components and equipment. Floodplain 

management regulations allow enclosures greater than 

300 square feet, but structures with these enclosures 

have higher NFIP flood insurance premiums. Designers 

should consult a qualified insurance agent and review 

FEMA’s NFIP Flood Insurance Manual to determine 

insurance implications of design and construction 

decisions.

NFIP floodplain management regulations allow certain 

construction elements below the BFE that may or may not break away during the base flood (e.g., 

stairwells, elevator shafts, shear walls). These elements may or may not be considered obstructions for 

NFIP flood insurance rating purposes. For example:

• The NFIP floodplain management regulations in 44 CFR § 60.3(e) allow open wood lattice, insect

screening, and solid, non-load-bearing, breakaway walls below elevated buildings in Coastal High

Hazard Areas. Even though floodplain management regulations permit solid breakaway walls, garage

doors, and slats or lattice (with less than 40 percent of the area open), building designers and owners

EFFECT OF CONSTRUCTION 

BELOW THE BFE

Any construction or site development 

practice below the BFE (even piles 

and columns permitted by the NFIP) 

will cause a localized disruption of 

flow and waves during the base flood. 

The question is whether the localized 

disruption will be great enough to harm 

the elevated building or surrounding 

buildings.

Table 2: Comparison of Selected 2018 IBC and ASCE 24-14 Requirements with NFIP Requirements (continued)
14 NFIP TECHNICAL BULLETIN 5 MARCH 2020

should be aware that these elements can result in 

higher NFIP flood insurance premiums. See the text 

box “NFIP Flood Insurance Free-of-Obstruction 

Rate” below for details.

• The NFIP floodplain management regulations in

44 CFR § 60.3(e) restrict uses of space below the BFE

to parking of vehicles, building access, and storage.

Stairs, ramps, and elevators are permitted. However,

depending on how stairs, ramps, and elevators are

constructed, they may be considered obstructions

for NFIP flood insurance rating purposes and could

result in higher premiums.

5 Free-of-Obstruction Requirement 

Considerations

Some NFIP flood-resistant design and construction requirements, including free-of-obstruction 

requirements, are performance related and are not prescriptive. In other words, the expected building 

performance is stated, but how to achieve the performance is not specified. It is up to the design 

professional to create a design that complies with the free-of-obstruction performance requirements and 

up to the local official to determine whether the design satisfies the community’s requirements.

It is not always clear whether a particular building element or a site development practice would create 

a significant obstruction that would prevent the free passage of floodwater and waves. “Significant” is 

used because any construction element or site development practice below the flood level would cause a 

localized disruption of flow and waves during the base flood. Determining whether the disruption would 

be significant is not always easy because in most cases, there are no analytical or readily usable numerical 

DETERMINING FLOOD INSURANCE 

IMPLICATIONS BEFORE THE DESIGN

Design professionals and property 

owners may wish to contact a qualified 

insurance agent or the NFIP regarding 

the flood insurance rating and premium 

implications of obstructions before a 

building is designed.

NFIP FLOOD INSURANCE FREE-OF-OBSTRUCTION RATE

In order for a structure to qualify for the NFIP flood insurance free-of-obstruction rate, the space below 

the lowest elevated floor must be free of obstructions with the following exceptions:

• Insect screening provided that no additional supports are required for the screening

• Wooden or plastic lattice with at least 40 percent of its area open and constructed of material no

thicker than 1⁄2 inch

• Wooden or plastic slats or shutters with at least 40 percent of their area open and constructed of

material no thicker than 1 inch

• One solid breakaway wall or garage door with the remaining sides of the enclosure constructed of the

above-mentioned insect screening, wooden or plastic lattice, slats, or shutters
NFIP TECHNICAL BULLETIN 5 MARCH 2020 15

ENTRY DOOR AT TOP OF ACCESS STAIRS

Access stairs to elevated buildings are often constructed inside a breakaway enclosure with an entry 

door at the bottom of the enclosure but no entry door into the building at the top of the stairs. The lack of 

an entry door at the top results in a large opening in the building envelope when enclosures break away. 

Numerous post-disaster damage assessments have shown that loss of breakaway enclosures exposes 

building interiors to higher internal wind pressures and wind-driven rain. Loss of breakaway enclosures 

can also provide an easy path for floodwater to enter buildings, resulting in damage that can be avoided 

when doors are provided at the top of the access stairs.

Beginning with the 2015 IRC and ASCE 24-14, solid entry doors capable of resisting all design loads are 

required to be installed at the top of access stairs inside breakaway enclosures.

tools to answer the question with certainty. Local experience, results of post-disaster assessments, and 

application of coastal processes and building science principles must be relied on to reach a conclusion.

Some local floodplain management regulations require potential obstructions below or near a building 

to be evaluated to determine their effects on flow and waves. Fluid mechanics and coastal engineering 

references, such as the U.S. Army Corps of Engineers Coastal Engineering Manual (2002), provide some 

guidance, but the methods in these references are not generally capable of evaluating the potential effects 

of small building elements or small amounts of fill on flooding and waves during a base flood. Numerical 

coastal storm surge and wave models used in Flood Insurance Studies do not have sufficiently detailed 

resolution to discern building-sized disruptions to flow and wave fields.

Currently, developing models with fine enough resolution is technically challenging, time consuming, and 

cost prohibitive. And although recently developed, sophisticated numerical models show some promise in 

analyzing flow around buildings, their use is not economically feasible for most communities, owners, or 

designers interested in examining the potential obstructions discussed in this Technical Bulletin.

6 Building Elements Below

the Base Flood Elevation

This section discusses common building elements under elevated buildings that can impede the free 

passage of flood flow and waves. Following the guidance in this section will minimize potential obstructive 

effects and satisfy the NFIP free-of-obstruction requirement.

6.1 Access Stairs and Ramps

Access stairs and ramps that are attached to or beneath an elevated building may be enclosed with 

breakaway walls or unenclosed. However, like foundation bracing (see Section 6.8), stairs and ramps can 

impede breakaway walls from breaking away cleanly as intended. To minimize this possibility, unenclosed 

stairs and ramps are preferred, but if enclosures are used, the design should be such that the stairs and 
16 NFIP TECHNICAL BULLETIN 5 MARCH 2020

ramps do not interfere with breakaway wall performance. Enclosing stairways also affects NFIP flood 

insurance rates.

Stairs and ramps are not required to break away, but it is a design option. Stairs and ramps must be 

designed and constructed to either:

• Resist flood loads and remain in place during floods up to and including the base flood. If this option

is selected, the elevated building and its foundation must be designed to resist any flood loads that are

transferred from the stairs or ramp to the building, or

• Break away during base flood conditions without causing damage to the building or its foundation.

Figure 1 shows an example of an elevated building that was damaged as a result of stairs that did not 

break away cleanly; the stairway pulled out the exterior wall of the elevated building as the stairway failed.

Constructing access stairs with open sides (open guards and railings) and risers, to the extent allowed 

by building codes, minimizes the potential for flood loads acting on the stairs, thereby minimizing 

flood damage and also minimizing transfer of flood loads to the elevated building. Open stairs should 

be considered whenever possible (see Figure 2). Note that building codes may have maximum opening 

size limits on stair risers and railings, necessitating a longer run. Check with the local jurisdiction for 

requirements.

Ramps must be designed and constructed to minimize the obstruction of floodwater and waves and 

configured so that floodwater and waves cannot flow directly up the ramp toward the elevated building. 

This means that ramps should be positioned to avoid a straight alignment from the elevated building to 

the likely direction of wave and surge approach.

Figure 1:

Damage to an elevated

building as a result of stairs 

that did not break away 

cleanly
NFIP TECHNICAL BULLETIN 5 MARCH 2020 17

Massive exterior stairs are not permitted because they are inconsistent with the free-of-obstruction 

requirement and because other types of stairs can provide access. Figure 3 shows massive stairs that are 

attached to an elevated coastal home. These massive stairs will act as an obstruction and increase the 

likelihood of trapping or reflecting waves and flood flow beneath the elevated building.

In some cases, life-safety code requirements dictate that stairs and stairwells in structures of certain 

occupancy categories be constructed to be fire resistant and structurally stable even if portions of the 

adjacent structure fail. Stairs and stairwells that meet these requirements are usually constructed of 

some combination of steel, reinforced masonry, and reinforced concrete and will not break away under 

Figure 3: 

Massive stairs attached to 

an elevated coastal home, 

which act as an obstruction

Figure 2:

Open stairs, which minimize 

transfer of flood and wave 

forces
18 NFIP TECHNICAL BULLETIN 5 MARCH 2020

expected base flood loads and conditions. These stairs and stairwells, typically found in mid- and highrise buildings, must be designed to withstand all base flood loads, including flow, waves, and floodborne 

debris impacts.

6.2 Decks, Porches, and Patios

Decks, porches, and patios are typically outside the footprint of elevated residential and commercial 

buildings and may be constructed at grade, above grade but below the BFE, at the BFE, or above the BFE.

In Coastal High Hazard Areas, decks and porches outside the building footprint must meet one of the 

following conditions:

• If structurally attached to a structure, the bottom of the lowest horizontal structural member of the

deck or porch must be at or above the BFE. Deck and porch supports that extend below the BFE (e.g.,

pilings, bracing) must comply with Zone V design and construction requirements, and the structure

must be designed to accommodate any increased loads resulting from the attached deck or porch.

• If an attached deck or porch is located above the BFE but relies on support elements (posts, columns,

braces) that extend below the BFE, the supports must comply with Zone V design and construction

requirements.

• If a deck, porch, or patio (not counting its supports) lies in whole or in part below the BFE, it must be

structurally independent from the structure and its foundation system.

Decks that are constructed within the building footprint between the ground and the elevated building 

are sometimes referred to as mezzanine decks. In Coastal High Hazard Areas, mezzanine decks should be 

treated similar to the floors of above-grade (elevated) enclosures (see Section 6.5). If directly below the 

footprint, a mezzanine deck that is structurally attached to the host building is treated as the lowest floor 

elevation for NFIP flood insurance rating purposes.

From a floodplain management perspective, mezzanine decks must meet building code requirements for 

dead, live, and other applicable loads and must be designed to either: 

1) Break apart into small pieces without causing collapse, displacement, or other structural damage

to the elevated building or the supporting foundation under flood loads less than those that occur

during the base flood or

2) Along with the building foundation, accommodate flood loads transferred from the mezzanine deck

to the building foundation during flooding up to and including base flood conditions.

Mezzanine decks may be independently supported on an open foundation and must be designed to either 

withstand flooding up to and including the base flood or break apart into small pieces under base flood 

or lesser conditions. Structurally independent decks below the BFE and below a structure’s footprint are 

not considered the lowest floor for NFIP flood insurance purposes.

Decks, porches, and patios must not adversely affect the structure with which they are associated, or 

nearby structures, by diverting floodwater and waves during flood conditions up to and including the 

base flood. Some decks and patios, such as low-profile decks and patios constructed at natural grade 

or on minor quantities of fill necessary to level the site (see the textbox in Section 7.5), are deemed to 

comply by minimizing harmful diversion of floodwater or wave runup and reflection. A low-profile deck 

or patio, as used here, has a floor system depth of 12 inches or less, some of which may be below the 
NFIP TECHNICAL BULLETIN 5 MARCH 2020 19

adjacent finished grade. The depth does not include railings, which should be open to allow water to flow 

through. Attaching seats, benches, tables, planters, or similar features will cause a deck or patio to lose its 

deemed-to-comply low-profile classification. These features may or may not be obstructions (depending 

on size, number, and configuration) and should be evaluated for potential effects on flow and waves.

Decks, porches, and patios must be designed and constructed so that when subject to flooding up to 

and including base flood conditions, they do not create debris capable of causing significant damage to 

nearby structures. This means that decks, porches, and patios must remain intact and in place during 

base flood conditions or break apart into small pieces so the resulting debris does not lead to structural 

damage to nearby structures.

Decks and porches that are structurally attached to structures in Zone V must be supported to resist the 

simultaneous action of design wind loads and base flood loads. Most attached decks and porches are 

supported on piles or columns embedded in the ground and are capable of surviving anticipated erosion 

and scour. Post-storm assessments frequently identify decks and porches that were elevated on posts whose 

diameters were too small or on structural elements without sufficient embedment into the ground. The 

result of inadequate support is loss of decks and porches and sometimes damage to elevated structures. 

Unless the building code or local community prescribes otherwise, the foundation for an elevated deck or 

porch attached to a structure in Zone V should be similar to the structure’s foundation. Attached decks 

and porches may be cantilevered from main structures instead of supported on piles or columns.

6.3 Elevators

Elevators attached to or beneath elevated structures 

in Zone V must comply with building, fire, electrical, 

and mechanical code requirements. Elevators and 

elevator shafts are not required to break away but 

must meet flood damage-resistant material and 

equipment requirements.

Flood loads acting on elevator components, any nonbreakaway shaft walls, and potential wave runup and 

reflection effects must be accounted for in the design 

of the elevated structure and its foundation system. 

Therefore, it is advantageous to minimize the size of 

elevators, especially residential elevators in one- and two-family structures. Elevators should be designed 

and installed to satisfy the requirements of ASCE 24, which FEMA has determined meets or exceeds the 

minimum NFIP requirements. Additional guidance can be found in NFIP Technical Bulletin 4, Elevator 

Installation for Buildings Located in Special Flood Hazard Areas.

6.4 Enclosed Areas

The types of enclosed areas that are discussed in this section are:

• Enclosed areas below elevated structures

• Above grade (elevated) enclosures

• Two-level enclosures

NFIP FLOOD INSURANCE

AND ELEVATOR SHAFTS

AND ELEVATOR EQUIPMENT 

Elevator shafts and elevator equipment 

below the BFE will result in higher NFIP 

flood insurance premiums. The presence 

of elevators always increases the 

premium, regardless of how the shafts are 

constructed.
20 NFIP TECHNICAL BULLETIN 5 MARCH 2020

6.4.1 Enclosed Areas Below Elevated Structures

The use of enclosed areas below elevated 

structures is restricted to parking of vehicles, 

building access, and storage. Enclosed areas 

must not be used for habitable purposes. 

Enclosed areas, including foyers, must 

be constructed of flood damage-resistant 

materials and not be finished. All enclosed 

areas below elevated buildings will be 

considered when the NFIP flood insurance 

premium is determined.

The NFIP regulations in 44 CFR § 60.3(e)(5) 

state that the area beneath the elevated 

portion of a structure in Zone V may be 

enclosed only with open lattice, insect 

screening, or non-supporting breakaway 

walls (see NFIP Technical Bulletin 9, Design 

and Construction Guidance for Breakaway 

Walls Below Elevated Buildings in Coastal 

High Hazard Areas). However, while NFIP 

regulations permit all enclosure walls to be 

solid breakaway walls, construction of such 

will lead to a With-Obstruction rating by the 

NFIP.

FEMA guidance states that the following 

lattice and slats are acceptable:

• Wood or plastic lattice no thicker than

1⁄2 inch with at least 40 percent of its area

open

• Wood or plastic slats or fixed louvers no thicker than 1 inch that, when installed, have at least

40 percent of their area open

Figure 4 and Figure 5 show examples of compliant slats, which are typically installed flat against foundation 

pilings (see Figure 4) or angled like louvers between the pilings (see Figure 5). Percent open area of a 

lattice or louver wall should be calculated based on the area through which water can flow through lattice 

or louvers, divided by the total area of the enclosure wall (see Figure 6).

PRIVACY SCREENING 

Privacy screening around outdoor shower areas is 

permitted if the sides are open at top and bottom 

and the screening will break away under base flood 

or lesser conditions. If a space under the building 

footprint is enclosed with privacy screening, there will 

be an NFIP flood insurance premium increase.

SIZE OF ENCLOSURES

AND NFIP FLOOD INSURANCE 

The NFIP does not limit the size of enclosures under 

elevated structures. However, higher NFIP flood 

insurance premiums will generally be assessed for 

structures in Zone V with enclosed areas of any 

size (including stairwells and elevator enclosures), 

even if enclosed by breakaway walls. Annual NFIP 

premiums can be even higher when buildings have 

enclosures that are 300 square feet or larger. Some 

communities have adopted restrictions or prohibitions 

on enclosures. Designers, contractors, and owners 

should check local requirements prior to construction.

The NFIP does not require flood openings in the walls 

of enclosures in Zone V. However, beginning with 

ASCE 24-14 and the 2015 IRC and IBC, enclosures in 

Zone V require flood openings.
NFIP TECHNICAL BULLETIN 5 MARCH 2020 21

Figure 4: 

Compliant wood slats 

installed flat against 

foundation pilings

Figure 5: 

Compliant, fixed, wood 

louvers installed between 

pilings
22 NFIP TECHNICAL BULLETIN 5 MARCH 2020

Figure 7 shows an elevated building in which a portion of a solid breakaway wall enclosure did not break 

away. Waves were not able to pass beneath the elevated structure, and wave runup against the enclosure 

wall likely caused damage above the elevated floor.

Figure 6: Determination of the percentage of open area for a lattice or louver wall

Figure 7: 

Breakaway wall that did not 

break away, which led to 

wave runup and contributed 

to flood damage on the side 

of the elevated building
NFIP TECHNICAL BULLETIN 5 MARCH 2020 23

ABOVE-GRADE ENCLOSURES

AND NFIP FLOOD INSURANCE 

NFIP flood insurance policies for elevated 

buildings with above-grade enclosures are 

rated assuming the floor of the above-grade 

enclosure is the lowest floor (or based on the 

elevation of the lowest horizontal structural 

member of the enclosure instead of the lowest 

horizontal structural member of the lowest floor 

of the elevated building). Owners should ask 

their insurance companies to submit requests 

to the NFIP for a special rating for buildings 

with above-grade enclosures.

Figure 8:

Above-grade enclosure

6.4.2 Above-Grade Enclosed Areas (Elevated) 

Another enclosure option is to construct enclosures with floor systems that are elevated above grade and 

are not in contact with the ground (see Figure 8). Placing the enclosure floor above grade minimizes the 

potential for damage to the enclosure and contents during frequent, low-level flood events.

An above-grade enclosed area (sometimes referred to as a hanging enclosure) is any enclosure with its 

floor system above grade. The enclosure may be supported by a foundation beneath the enclosure or by 

the elevated building and/or building foundation. A hanging floor is the lowest floor elevation for NFIP 

flood insurance rating purposes.

Above-grade enclosures may be used only for 

storage and building access and must meet all other 

requirements applicable to enclosures, including 

the use of breakaway walls and flood damageresistant materials below the BFE. Additionally, 

mechanical and electrical systems in the enclosure 

must be elevated to or above the BFE. A floor grate 

should be installed in the enclosure floor, and 

flood openings should be installed in breakaway 

enclosure walls. The grate will reduce vertical 

uplift (buoyancy) loads on the enclosure floor 

before water flows through the openings in the 

enclosure walls and allow the elevated enclosure to 

drain fully, reducing the downward load caused by 

water that would otherwise be trapped above the 

enclosure floor.
24 NFIP TECHNICAL BULLETIN 5 MARCH 2020

The design of the foundation and enclosure 

floor system for above-grade enclosures that 

are in Zone V must meet one of the following 

conditions:

• The floor system is designed to break 

away under flood loads less than those 

that occur during the base flood without 

causing collapse, displacement, or 

other structural damage to the elevated 

building or the supporting foundation 

(see Figure 9), or

• The floor system is designed to remain 

in place and intact, and the building 

foundation is designed to accommodate 

flood loads transferred from the 

enclosure floor system to the foundation 

during flood conditions up to and 

including the base flood (see Figure 9), 

or

• The enclosure floor system is 

independently supported on an open 

foundation (see Figure 10).

Flood openings in above-grade enclosure 

walls are required by the building code 

but do not reduce NFIP flood insurance 

premiums for the enclosure.

6.4.3 Two-Level Enclosed Areas 

In flood hazard areas where the BFE is 

very high above the ground or where 

owners elect to elevate buildings very 

high, some owners opt to build two-level 

enclosures (see Figure 11 and Figure 12). 

Two-level enclosures are permitted but not 

recommended due to their more complicated 

construction and increased potential for 

Figure 9: Above-grade enclosure floor system attached to building 

foundation

Figure 10: Above-grade enclosure supported by independent 

foundation

TWO-LEVEL ENCLOSURES 

Two-level enclosures are also known 

as two-story enclosures, double 

enclosures, and stacked enclosures.
NFIP TECHNICAL BULLETIN 5 MARCH 2020 25

floodborne debris. Two-level enclosures could also result in the floor of the upper level being considered 

the lowest floor for NFIP flood insurance rating purposes.

Both levels of the enclosure must meet all of the floodplain management and building code requirements 

for enclosed areas, including breakaway walls, elevated utilities, flood damage-resistant materials, and 

limitations on use (parking of vehicles, building access, and storage). The floor system of the upper 

enclosure level must be designed to meet one of the options for above-grade (elevated) enclosed areas 

(see Section 6.4.2).

Openings with grates should be installed in the floor to facilitate drainage from the upper level enclosure. 

In the event that floodwater enters the upper level but does not cause failure of the breakaway walls, the 

floor grates will allow trapped water to drain to the lower level and not overload the upper level floor 

system.

TWO-LEVEL ENCLOSURES AND NFIP FLOOD INSURANCE 

Designers and owners should be aware that a building with a two-level enclosure, even if allowed 

by permit, could result in higher NFIP flood insurance premiums than if the building has a one-level 

enclosure. Even if a two-level enclosure complies with building code and floodplain management 

requirements for enclosures, the upper floor of the two-level enclosure could be deemed the lowest floor 

for NFIP flood insurance rating purposes (the lowest floor elevation for flood insurance purposes is the 

first floor elevated above ground). Owners should ask their insurance companies to submit requests to 

the NFIP for a special rating for buildings with two-level enclosures.

Figure 11: 

Two-level enclosure
26 NFIP TECHNICAL BULLETIN 5 MARCH 2020

6.5 Mechanical, Electrical, and Plumbing Equipment, Ducts, 

Tanks, and Fixtures

Mechanical, electrical, and plumbing equipment, 

ducts, tanks, and fixtures serving elevated buildings 

are required to be elevated to or above the BFE or 

protected from water entry during the base flood.

There are exceptions for elevator equipment that 

cannot be elevated (see NFIP Technical Bulletin 4, 

Elevator Installation for Buildings Located in Special Flood 

Hazard Areas, and ASCE 24).

EQUIPMENT BELOW AN ELEVATED 

BUILDING AND NFIP FLOOD INSURANCE 

Designers and owners should be aware that 

elevator equipment and other equipment 

below an elevated building will result in 

higher NFIP flood insurance premiums, even 

if the equipment is allowed by permit.

Figure 12:

Two-level enclosure schematic
NFIP TECHNICAL BULLETIN 5 MARCH 2020 27

Utility lines, pipes, risers, and chases may need to 

extend below the BFE but should be installed to 

minimize potential damage from flooding (some 

utility companies place meters below the BFE so they 

can be easily accessed). The following help minimize 

potential damage:

• Utility lines, pipes, risers, and chases are not

allowed to be attached to or penetrate through

breakaway walls (see Figure 13).

• Utility lines, pipes, risers, and chases should be

located on the sides of piles and columns that are

opposite the anticipated direction of flood flow

and wave approach, where possible.

Fuel tanks and other tanks serving elevated buildings 

and located under or adjacent to the buildings must 

be in-ground or elevated above the BFE. In both 

cases, tanks should be anchored to prevent flotation 

or lateral movement during base flood conditions. 

Platforms supporting elevated tanks should resist 

flooding up to and including base flood conditions.

To satisfy free-of-obstruction requirements, aboveground tanks must not be located beneath elevated 

buildings or attached to elevated buildings below the 

BFE. This requirement also applies to permanently 

UTILITY CHASES 

For floodplain management and NFIP flood 

insurance purposes, utility chases designed 

to protect utility lines from freezing are 

not considered enclosures. Utility chases 

must be small and not allow access for a 

person to enter the space (access panels for 

servicing the lines are appropriate).

Because a utility chase is not considered 

an enclosure, it does not have to meet the 

requirement of breakaway walls, louvers, or 

open latticework; however, the chase may 

be breakaway under flood conditions.

The utility chase must be constructed 

of flood damage-resistant materials 

below the BFE, and the enclosed utility 

lines must meet the requirement to be 

watertight and capable of withstanding 

flood loads (hydrostatic, hydrodynamic, 

wave). Additionally, the portions of the utility 

system located below the BFE and the utility 

chase should not be attached to, mounted 

on, pass through, or be located along 

breakaway walls.

Figure 13: 

Utilities mounted on wall, which 

prevented the wall from breaking 

away cleanly
28 NFIP TECHNICAL BULLETIN 5 MARCH 2020

installed fuel tanks for outdoor kitchens. Portable gas grills and associated propane fuel tanks and similar 

devices for which building permits are not required are not subject to these requirements. However, 

communities may have other fire and life-safety requirements that must be met. In addition, when 

flooding is anticipated, owners should move portable grills and propane fuel tanks to a safe location 

where they will not pose a hazard or become floodborne debris.

Additional guidance can be found in FEMA P-348, Protecting Building Utilities from Flood Damage (2017), 

and FEMA P-259, Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures (2012).

6.6 Foundation Bracing

Foundation bracing is often used to stiffen pile foundations and/or improve comfort and reduce sway in 

elevated buildings. However, foundation designs without bracing are preferred in coastal areas because 

they minimize obstructions to flow and waves.

Free-of-obstruction considerations call for using only the minimum amount of foundation bracing 

necessary to achieve a stable design, and such bracing should be designed to withstand flood conditions 

up to and including the base flood. Additional bracing may be used to improve the comfort of building 

occupants (i.e., reduce building sway under non-flood conditions), but the additional bracing should not 

be as strong as that required for structural stability and should not be relied on to yield a stable design, as 

it may be lost during a flood.

Many coastal construction experts and design references advise relying on shore-perpendicular bracing 

and minimizing the use of shore-parallel bracing. However, because wind and seismic loads can act in any 

direction, this alternative may not always provide the structural stability that is required in some locations. 

Increasing the number of piles (by decreasing horizontal spacing), detailing moment connections at the 

tops of the piles (in the case of concrete piles and beams), and using grade beams are accepted ways 

of eliminating or reducing the need for foundation bracing. Designers may determine other ways to 

minimize the amount and type of bracing.

Diagonal timber cross-bracing is the most common type of bracing used on foundations under coastal 

homes. Unfortunately, timber braces frequently fail during severe flood events as a result of wave or debris 

impacts. If they survive, they can interfere with breakaway wall failure, trap debris, and transfer lateral 

flood loads to the foundation. Metal rod braces, while less susceptible to failure, can also trap floating 

debris (see Figure 14). Knee braces at the tops of pilings are sometimes preferred (Figure 15) because 

their position higher up on the pilings will present less obstruction to flow and waves.

When foundation bracing below the BFE is used, it must be placed so as not to interfere with the intended 

failure of breakaway wall panels (see Figure 16). Avoiding interference may require eliminating breakaway 

walls, shifting the location of breakaway walls, or redesigning the foundation so the need for certain 

braces is eliminated. Breakaway walls and foundation bracing should not be placed close to each other if 

either could adversely affect the intended performance of the other.
NFIP TECHNICAL BULLETIN 5 MARCH 2020 29

Figure 16: Cross bracing that interfered with the 

failure of a breakaway wall

Figure 15: Knee bracing

Figure 14:

Floating debris trapped by metal rod 

cross bracing
30 NFIP TECHNICAL BULLETIN 5 MARCH 2020

SHEAR WALLS 

ASCE 24 contains flood-related 

requirements and limitations 

for shear walls used to support 

buildings in Zone V. Contact your 

local building department for rules 

and building code requirements 

for shear walls in Zone V.

6.7 Grade Beams

Grade beams are horizontal elements at or below the ground surface that tie the foundation piles or 

columns together and provide additional lateral support. They are typically reinforced concrete or wood.

Grade beams that are placed with their upper surfaces flush with or below the natural grade (the grade 

before the site is altered by fill or grading, if any) are not considered obstructions and are allowed by 

NFIP. However, storm erosion and local scour can expose and undermine grade beams, sometimes leaving 

them suspended above the post-storm ground profile. Designers must anticipate this circumstance and 

design grade beams to resist flood, wave, and debris loads and to remain in place and functional when 

undermined by scour and erosion (see Figure 17). Grade beams must also be designed and constructed 

so the vertical thickness is minimized, thereby reducing the lateral flood, wave, and debris loads acting on 

the beam and minimizing the transfer of these loads to the foundation.

6.8 Shear Walls

The NFIP regulations in 44 CFR § 60.3(e) state that only pile 

and column foundations are permitted in Zone V. In practice, 

this requirement has been relaxed by the NFIP and building 

codes for mid- and high-rise structures to allow certain types 

of solid walls, called shear walls, if detailed engineering 

calculations demonstrate that such walls are required to 

transfer lateral loads acting on upper stories to the ground, 

particularly in extreme-wind zones (see Figure 18). Even in 

these cases, shear walls should be used only if foundations and 

buildings are designed to resist all base flood conditions, all 

other design loads, and all appropriate load combinations.

Shear walls should be constructed parallel to the anticipated direction of flood flow and wave attack 

(typically perpendicular to the shoreline) to allow floodwater and waves to pass freely. In some cases, 

building designs require both shore-perpendicular and shore-parallel shear walls. Use of shore-parallel 

shear wall segments should be limited to the minimum length required to transfer upper-story loads to 

Figure 17:

Grade beams that were exposed 

to flood forces during hurricaneinduced scour; grade beams must 

resist flood, wave, and debris 

loads when undermined
NFIP TECHNICAL BULLETIN 5 MARCH 2020 31

Figure 18:

High-rise buildings elevated on 

shore-perpendicular shear walls

the foundation. Shore-parallel shear walls should be designed with openings in the walls or gaps between 

shear wall segments to minimize trapping of floodwater, waves, and debris and minimize the total flood 

loads acting on the building. In any case, designs of these walls must be certified by registered design 

professionals as part of the requirement for certification of foundation designs.

Low-rise buildings in Zone V should be designed with pile or column foundations that are consistent 

with the NFIP regulations. Post-flood assessments have found that shear walls supporting older low-rise 

buildings often do not survive severe storm events. See Figure 19, which shows the failure of a wall section 

of a building supported on columns and shore-perpendicular walls. Wall failure led to failure of the 

elevated floor beam and floor. In this instance, the building was an older non-conforming building, and 

the solid walls rested on shallow footings (a means of support not permitted by the NFIP or building 

codes for buildings in Zone V). The wall failure was likely due to both lateral flood loads and foundation 

undermining.
32 NFIP TECHNICAL BULLETIN 5 MARCH 2020

6.9 Slabs

Concrete slabs are commonly used beneath elevated 

buildings in Zone V for vehicle parking and as floors of 

enclosed storage or building access areas. The vertical 

elements elevating the building should not rest on 

the slab to avoid an NFIP flood insurance rating of 

“non-elevated.”

Post-disaster assessments conducted by FEMA have 

concluded that unreinforced slabs less than 4 inches 

thick tend to break up into small pieces without causing 

adverse effects to elevated buildings (see Figure 20). Reinforced concrete slabs thicker than 4 inches 

tend not to break up into small pieces, can become dislodged and act as obstructions, and can transfer 

unanticipated loads to building foundations (see Figure 21).

SLABS AND NFIP FLOOD INSURANCE 

There is no difference in NFIP flood 

insurance premiums between having 

a frangible slab or a self-supporting 

structural slab for two otherwise identical 

elevated buildings.

Figure 19:

Failure of a shore-perpendicular 

solid foundation wall that 

supported a low-rise building, 

which resulted in failure of the 

beam and floor system that 

were supported by the shoreperpendicular wall
NFIP TECHNICAL BULLETIN 5 MARCH 2020 33

Post-disaster assessments have determined that slabs perform well if they meet the requirement in 

ASCE 24-14, Section 9.3, to either:

• Be frangible (break into small pieces), floating slabs supported by compacted soil, not attached to

the building foundation, and designed and constructed with a maximum thickness (traditionally

4 inches), without reinforcement and without turned down edges, or

• Be designed and constructed as self-supporting structural slabs capable of remaining intact and

functional during flooding up to and including base flood conditions, including expected erosion.

Building foundations must be capable of resisting any added loads and increase in local scour due to the 

presence of the slabs.

Figure 20:

Damage to building foundation 

caused in part by failure of the 

reinforced slab undermined by 

erosion

Figure 21:

Unreinforced slab that broke apart 

without imposing loads on the 

foundation
34 NFIP TECHNICAL BULLETIN 5 MARCH 2020

In most circumstances, and for low-rise buildings in Zone V (including residences), the best alternative 

is to use frangible slabs. This alternative is also appropriate for other uses of slabs, such as pool decks, 

sidewalks, and patios. Figure 22 illustrates one possible design for such a slab.

Figure 22: Example of frangible slab design
NFIP TECHNICAL BULLETIN 5 MARCH 2020 35

Reinforced, self-supporting structural slabs below the BFE may be appropriate for large mid- and highrise structures that are supported on deep piles because these structures are typically much heavier and 

less prone to damage from flood loads. If a frangible parking slab is constructed beneath such a structure, 

reoccupation of an otherwise intact and usable structure after a severe coastal storm event may be delayed 

due to loss of parking. A self-supporting structural slab could be considered in such situations.

Reinforced, self-supporting structural slabs and grade beams beneath large buildings should be designed 

to be only as thick as necessary to support vehicle loads and other design loads. The slabs and beams 

should be connected and integral to the foundations, and all below-BFE components should be designed 

to act together to resist flood loads and other design loads. Obstructive effects will be minimized as long 

as the slab systems remain intact and horizontal so floodwater and waves pass above and below the slabs.

7 Site Development:

Practices and Issues

This section discusses common site development practices and issues that may significantly affect the 

free passage of flood flow and waves under or around elevated buildings. When these practices are 

undertaken in accordance with the guidance in this section, they will be deemed to satisfy the NFIP freeof-obstruction requirement, and the potential obstructive effects will be minimized.

7.1 Accessory Storage Structures

In Zone V, certain small accessories structures (as defined 

in a community’s floodplain management ordinance, 

which has been approved by FEMA) may be permitted 

below the BFE. Small accessory structures include small 

storage structures such as metal, plastic, or wood sheds that 

are disposable. FEMA considers “small” to mean less than 

or equal to 100 square feet.

If accessory storage structures below the BFE do not 

meet the size considerations mentioned above, or if the 

structures are of significant size and made of material that 

is likely to create either damaging debris or flow and wavediversion problems, communities could consider granting 

variances in accordance with their floodplain management 

ordinances and 44 CFR § 60.6. Alternatively, a best practice 

is to have accessory storage structures constructed and 

elevated in compliance with NFIP requirements.

ADDITIONAL ACCESSORY 

STRUCTURE CONSIDERATIONS 

Some communities have FEMAapproved regulations that specify 

limitations on the size of accessory 

structures that are allowed in 

SFHAs without having to comply 

with elevation requirements. Other 

considerations for accessory 

structures are set forth in FEMA 

policies and guidance.

Local officials should consult NFIP 

State Coordinators or FEMA Regional 

Offices for additional guidance and for 

appropriate size limits and language to 

include in local regulations.
36 NFIP TECHNICAL BULLETIN 5 MARCH 2020

Small accessory storage structures that are not elevated must be anchored to resist wind loads (see 

Figure 23) and designed to resist flotation that may occur even under relatively shallow flood depths. 

However, because small accessory storage structures are unlikely to withstand wave loads, their loss should 

be anticipated during the base flood, and the effects that resultant debris may have on nearby structures 

must be considered. 

In addition, small accessory storage structures must be unfinished on the interior, constructed of flood 

damage-resistant materials, and used only for storage; moreover, if a structure is provided with electricity, 

the service must be above the BFE with all branch circuits descending below the BFE fed from groundfault circuit interrupter breakers. Accessory storage structures must not be used for any habitable or other 

prohibited purpose.

Separate accessory storage structures must not be located directly under elevated buildings. An alternative 

is to create storage space below the elevated structure by enclosing an area with breakaway walls.

7.2 Detached Garages

Detached garages, such as those typically built for singlefamily homes or multi-family structures, are too large to 

qualify as accessory structures that are allowed below the BFE 

(see Section 7.1). Therefore, detached garages must be elevated 

on piles or columns and comply with other requirements for 

structures in Zone V.

Large, fully engineered, free-standing parking garages that satisfy 

Zone V design and construction requirements are permitted, 

even if portions lie below the BFE (e.g., vehicle ramps, stairwells, 

elevator shafts, parking spaces). These structures are not walled 

and roofed in the traditional sense and can be designed to allow 

the free passage of floodwater and waves.

ALTERNATIVE

TO DETACHED GARAGES 

Garages may be constructed 

under elevated buildings and 

enclosed with breakaway walls 

(see Technical Bulletin 9, Design 

and Construction Guidance for 

Breakaway Walls).

Figure 23:

Small accessory structure that was 

moved by flood and wind forces
NFIP TECHNICAL BULLETIN 5 MARCH 2020 37

EFFECT OF EROSION CONTROL 

STRUCTURES ON WAVES 

Guidance for evaluating potential effects 

of erosion control structures on waves 

is contained in the U.S. Army Corps of 

Engineers Coastal Engineering Manual 

(2002 and updates). Generally, erosion 

control structures with a steep face (1:2 

[vertical to horizontal] or steeper) result in 

the greatest wave runup.

7.3 Erosion Control Structures

Erosion control structures, such as bulkheads, 

seawalls, retaining walls, and revetments, are 

obstructions when installed beneath elevated coastal 

buildings and are not permitted even if not attached to 

the building foundations. Erosion control structures 

can transfer damaging flood loads to building 

foundations and greatly increase the potential for 

redirecting flood flow and waves onto the elevated 

portions of coastal buildings). Figure 24 shows an 

example of waves running up and overtopping an 

erosion control structure. Figure 25 shows an example 

of timbers attached to a pile foundation (constituting 

a bulkhead), which is not permitted.

Figure 24:

Wave runup and overtopping 

at an erosion control 

structure

Although the NFIP does not prohibit bulkheads, seawalls, retaining walls, or revetments outside a 

building’s footprint, communities and design professionals must carefully consider the potentially 

significant effects of these structures. A general rule of thumb is the greater the horizontal distance 

between an erosion control structure and a building, the less likely that wave runup and overtopping 

will adversely affect the building. Although local or state regulations may prohibit the construction of 

erosion control structures until erosion is within a few feet of a building foundation (to maximize the 

recreational beach area seaward of the structure), the proximity of erosion control structures to buildings 

may contribute to wave runup and wave reflection damage.
38 NFIP TECHNICAL BULLETIN 5 MARCH 2020

FEMA’s coastal mapping guidance suggests that a 30-foot-wide “VE overtopping splash zone” (the 

area where waves breaking on or running up the seaward face of an erosion control structure land or 

splash down) be mapped landward of erosion control structures, but the guidance also contains sitespecific calculations that can lead to a narrower splash zone. For floodplain management purposes, a 

30-foot minimum splash zone width is desirable for new construction landward of existing erosion

control structures, but this width may not be feasible for existing buildings situated close to erosion

control structures. There is no established minimum distance between a building and an erosion control

structure, but a reasonable minimum width is 10 to 15 feet. States and communities should take local

conditions and observed building damage into account when establishing minimum distances.

7.4 Fences and Privacy Walls

Fences and privacy walls, including walls separating one property from another, may obstruct or divert 

flood flow and waves toward buildings. Their potential effects on buildings, including debris generation, 

should be evaluated. Open fences (e.g., wood, plastic, open masonry units, metal slat fencing with 

generous openings) are presumed to not cause harmful diversion of floodwater or wave runup and 

reflection. Fences with small openings and solid fences and walls may divert flow and waves and can trap 

debris.

Solid fences, privacy walls, and fences prone to trapping debris must be designed and constructed to fail 

under base flood conditions without causing harm to nearby buildings. Where building or fire codes 

require ground-level walls for tenant fire separation, designers should strive to satisfy code requirements 

while minimizing potential adverse effects from flood diversion.

Figure 25:

Shore-parallel timbers attached 

to a pile foundation that were 

intended to act as a bulkhead but 

constituted an obstruction and are 

not permitted
NFIP TECHNICAL BULLETIN 5 MARCH 2020 39

Siting of new buildings near fences and privacy walls should be reviewed carefully given the impact that 

these structures could have on a building if they fail during a flood event. Figure 26 shows an example 

of a shore-perpendicular solid privacy wall that failed during a coastal flood event and damaged the pile 

foundation of an adjacent elevated building.

Figure 26:

Shore-perpendicular 

reinforced masonry 

privacy wall that 

collapsed into the 

foundation of an 

adjacent building 

and contributed to 

failure of the corner 

foundation piling and 

pile cap/beam

MINOR GRADING AND MINOR QUANTITIES 

OF NONSTRUCTURAL FILL 

Minor grading: Minimum grading necessary to 

provide for landscaping and drainage purposes 

required or allowed by community regulations, 

subject to the limitations described in this 

Technical Bulletin.

Minor quantity of fill: Minimum quantity 

necessary to provide for adequate drainage 

of areas below and around elevated buildings; 

support of parking slabs, in-ground pool 

decks, decks, patios, walkways, and similar 

site elements; and for site landscaping, subject 

to the limitations described in this Technical 

Bulletin.

7.5 Fill

NFIP regulations prohibit the use of fill for 

structural support of buildings in Zone V. Minor 

grading and the placement of minor quantities 

of nonstructural fill are allowed in Zone V 

but only for landscaping, drainage under and 

around buildings, and support of parking slabs, 

pool decks, patios, walkways, and similar site 

elements. Nonstructural fill should not prevent 

the free passage of floodwater and waves beneath 

elevated buildings, divert floodwater or waves 

such that building damage is exacerbated, or 

lead to damaging flood and wave conditions on a 

site or adjacent sites. Nonstructural fill should be 

assumed to wash away and should not be used in 

foundation design calculations.

Determining whether the placement and 

shaping of nonstructural fill will be detrimental 

is complicated. Therefore, some state and local 
40 NFIP TECHNICAL BULLETIN 5 MARCH 2020

regulations essentially prohibit placement of any nonstructural fill in Zone V. However, such limits on 

nonstructural fill can also lead to problems such as ponding of rainfall around or under buildings. Other 

states and communities accept some (unspecified) amount of nonstructural fill provided an engineering 

analysis is performed and an engineer certifies that the fill will not lead to damaging flow diversion or 

wave runup and reflection. However, credible and defensible analyses are difficult to perform using 

current engineering methods and models for the small quantities of fill typically used on individual lots.

The placement of nonstructural fill in Zone V for landscaping, drainage, and slab support may be 

acceptable under certain circumstances using the evaluation criteria described below. Unless in conflict 

with state or local limitations, local officials are expected to apply these criteria using discretion to 

achieve the desired performance while giving deference to the general intent of the following criteria as 

described in the paragraphs that follow. Several criteria are listed, and they may not all agree, depending 

on specific circumstances.

7.5.1 Type of Fill

Fill placed on Zone V sites should be similar to natural soils in the area. In many coastal areas, natural soils 

are clean sand or sandy soils free of large quantities of clay, silt, and organic material. Nonstructural fill 

should not contain large rocks and debris. If the fill is similar to and compatible with natural soils, there is 

no need to require designers to investigate or certify whether the fill has a tendency for excessive natural 

compaction; an investigation or certification is a common requirement in many floodplain regulations. 

If the fill material is similar to natural soils, its behavior under flood conditions will be similar to the 

behavior of natural soils.

7.5.2 Fill Thickness

The addition of small thicknesses of site-compatible, nonstructural fill in Zone V is not likely to lead 

to adverse effects on buildings. There are no established rules as to what constitutes an acceptable fill 

thickness, so it must be addressed on a case-by-case basis and in some cases may require an engineering 

analysis of flow and wave effects of the fill. Designers should check with the community about fill thickness 

thresholds triggering engineering analyses.

Placement of up to 2 feet of fill under or around an elevated building can generally be assumed to comply 

with free-of-obstruction requirements and be acceptable without engineering analysis or certification, 

provided basic site drainage principles are not violated (see Section 7.5.4) and provided there are no 

other site-specific conditions or characteristics that would render the placement of the fill damaging to 

nearby buildings (e.g., if local officials have observed that the placement of similar quantities of fill has 

led to building damage during coastal storm events).

If fill is proposed for a site, the proposed final grade should be compared to local topography. If the 

proposed final fill configuration is below the threshold established by the community and the fill 

configuration is similar to grades and slopes in the immediate vicinity, a detailed analysis of the effects 

on flood flow and waves may not be needed. However, if the proposed fill configuration exceeds the 

community’s configuration deemed to comply fill thickness threshold or the proposed fill configuration 

exceeds local grade heights and variations, an engineering analysis may be required by the community.

In cases where site development involves removing a layer of soil and fill is added to the site later, the fill 

thickness should be evaluated relative to the pre-removal soil elevation, not the removed soil elevation.
NFIP TECHNICAL BULLETIN 5 MARCH 2020 41

7.5.3 Prevention of Ponding

Most communities establish minimum floor elevations to ensure that water does not collect at or under 

buildings. Floor elevation requirements are frequently tied to nearby road elevations, and the quantity of 

fill required to raise building footprint areas typically falls within the fill height allowance mentioned in 

Section 7.5.2. There is no compelling reason to restrict the placement of site-compatible, nonstructural 

fill beneath buildings in Zone V if the fill will prevent ponding and saturated soil conditions, as long as 

other drainage requirements for grades and slopes can be satisfied.

7.5.4 Site Drainage Requirements

Most communities establish minimum slopes for building sites to facilitate drainage away from buildings 

(typically 1 unit vertical to 20 units horizontal [5 percent]). Slopes of 1 unit vertical to 3 units horizontal 

(or steeper) can produce appreciable wave runup. Conversely, slopes shallower than 1 unit vertical 

to 5 units horizontal (regardless of fill height) will probably not cause or worsen wave runup or wave 

reflection capable of damaging adjacent buildings. Figure 27 shows an example of fill placement that is 

considered acceptable because the fill depth is modest and the side slopes are gentle. FEMA’s Hurricane 

Ivan Mitigation Assessment Team concluded that the presence and configuration of the fill did not cause 

additional flood or wave damage to either the elevated building or the nearby older non-elevated building 

(FEMA, 2005). The adjacent older, non-elevated building in Figure 27 would likely sustain structural 

damage during a coastal flood, even if the fill were not present. Swales and conventional site drainage 

practices should be used to mitigate potential effects of runoff from filled areas.

Figure 27: 

Post-hurricane photo 

showing an elevated building 

surrounded by gently 

sloping fill and an adjacent, 

damaged, older, non-elevated 

building
42 NFIP TECHNICAL BULLETIN 5 MARCH 2020

7.5.5 Vertical Clearance between Top of Fill and Bottom of Lowest Horizontal 

Structural Member of Lowest Floor

There are no established rules as to what constitutes acceptable vertical clearance, so it must be addressed 

on a case-by-case basis. Designers should check with the jurisdiction about minimum vertical clearance 

requirements.

When the BFE is above the existing ground, placement of nonstructural fill between the ground and the 

lowest horizontal structural member of the lowest floor may be permitted, but it is advisable to maintain 

some vertical clearance between the bottom of the lowest horizontal structural member and the top of the 

fill. Vertical clearance should be established to ensure that base flood flow and waves will pass beneath 

the elevated building and the fill will not contribute to wave runup and flood damage to the elevated 

building.

When the BFE is below the existing ground elevation (see Section 7.6), vertical clearance between the 

ground (including any nonstructural fill) and the lowest horizontal structural member of the lowest floor 

may not be needed as long as adequate site drainage is provided.

7.5.6 Fill Compaction

The NFIP regulations are explicit in that fill must not be used for structural support of buildings in 

Zone V. However, compaction of fill below and around elevated buildings used to support parking slabs, 

in-ground pool decks, patios, sidewalks, and similar site amenities is consistent with the intent of the 

regulations.

7.5.7 Dune Construction, Repair, and Reconstruction

Dunes are natural features in many coastal areas, and 

they can erode during storms and recover naturally over 

time. The natural recovery process can be accelerated 

by replacing the eroded dune with compatible sand, 

planting dune grasses, and installing sand fences (see 

Chapter 5 of The Dune Book [Rogers and Nash, 2003]). 

In general, these activities should not be considered 

detrimental even if part of the dune lies under a 

building’s footprint. The addition of sand to restore a 

site to its pre-storm grades and stabilization with dune 

vegetation will likely do more good than harm in terms 

of flood damage reduction.

Concerns about placement of nonstructural, clean 

sand under and around beachfront buildings should 

not be the basis for prohibiting dune maintenance and 

construction, beach nourishment, or similar activities. Dune construction, repair, and reconstruction 

under or around elevated buildings may be assumed to be acceptable as long as the scale and location 

of the dune work is consistent with local beach-dune morphology and reasonable vertical clearance is 

maintained between the top of the dune and the elevated building’s floor system. ASCE 24-14 permits 

DUNE EXCAVATION MAY INCREASE 

POTENTIAL FLOOD DAMAGE 

Communities must prohibit manmade 

alteration of sand dunes in Zone V if 

such alteration would increase potential 

flood damage (per 44 CFR § 60.3(e)(7)). 

Where the ground (dune) elevation is at 

or above the BFE, excavation to place the 

bottom of the lowest horizontal structural 

member of lowest floor at the BFE is not 

recommended and may in fact violate 

the limitation on alterations that increase 

potential flood damage.
NFIP TECHNICAL BULLETIN 5 MARCH 2020 43

dune construction and reconstruction under and around elevated buildings but requires an engineering 

report documenting that the fill placement will not cause building damage by wave runup or reflection or 

deflection of floodwater.

7.5.8 Timing of Fill Placement

Sometimes fill is placed on a site months or years before building construction begins. This can be 

problematic unless the community tracks site improvements and fill placement. If the original natural 

grade elevation is unknown, borings or other site investigations may be required to determine the depth 

of fill and ensure adequate foundation depth.

7.6 Ground Elevations At or Above the Base Flood Elevation

In some Zone V areas, ground elevations are at or above the BFE, particularly along shorelines with welldeveloped dune fields. Mapped Zone V areas with ground above the BFE seem counterintuitive, but they 

are possible because of two Zone V mapping considerations:

• Dune erosion. Dunes can erode during the base flood (or lesser floods), resulting in a substantial

lowering of the pre-storm grade to a level below the BFE. The BFE is mapped based on surge and

waves passing over the eroded and inundated ground surface.

• Presence of a primary frontal dune (PFD). Zone V is mapped at a minimum to the inland extent

(heel) of the PFD, even where the dune elevation is higher than the BFE (FEMA, 2014).

A ground elevation at or above the BFE may complicate the need to comply with Zone V design and 

construction requirements but does not eliminate it. It does raise the question of how the free-ofobstruction requirement applies in this situation: Because the soil at the site may erode during a 

coastal flood event, the area under the building will be exposed, and the exposed area must be free of 

obstructions.

The same free-of-obstruction considerations that apply to buildings elevated above grade apply to 

buildings where the BFE is below grade. Buildings must still be designed and constructed on pile or 

column foundations that are embedded deep into the ground, and the bottoms of the lowest horizontal 

structural members supporting the lowest floor must still be at or above the BFE. Vertical clearance 

between the bottom of the lowest horizontal structural member and the ground (see Section 7.5.5) is 

not required by the NFIP where ground elevations are at or above the BFE; however, communities should 

be contacted because they may have vertical clearance requirements. Any lowest horizontal structural 

members that come in contact with the fill must be composed of materials that can resist ground contact 

moisture levels. Minor site grading to drain water away from the foundation will also be necessary.

7.7 On-Site Septic Systems

On-site buried septic systems and mounded septic systems in Zone V are frequently exposed and/or 

displaced. In addition to compromising their subsequent use, damage can cause release of contents. 

Septic systems are often destroyed if they are near a shoreline. Therefore, septic systems should be located 

outside areas subject to erosion during the base flood or, if placed in an area subject to erosion, installed 

below the depth of expected erosion. The latter stipulation may conflict with septic system groundwater 

considerations, in which case an on-site septic system is not appropriate for the area, and alternate designs 

may be necessary.
44 NFIP TECHNICAL BULLETIN 5 MARCH 2020

On-site septic system tanks serving elevated buildings must not be structurally attached to building 

foundations. Plumbing and piping connections are required, and these items are allowed in Zone V. 

However, plumbing and piping components must not be attached to or pass through breakaway wall 

panels.

If mounded septic systems are used, they can require significant volumes of fill, which, if placed under 

or immediately adjacent to buildings, may constitute obstructions that divert flood flow and waves. An 

analysis of flow and wave effects should be undertaken. Mounded septic systems may be allowed in Zone 

V if they will not worsen flood and wave conditions for the buildings they serve or nearby buildings (see 

Section 7.5.2 for guidance on evaluating mounded systems near elevated buildings).

An additional consideration for on-site septic systems in Zone V is stated in 44 CFR § 60.3(a)(6)(ii) of 

the NFIP regulations, which requires “on-site waste disposal systems to be located to avoid impairment to 

them or contamination from them during flooding.” FEMA P-348 provides additional guidance.

7.8 Restroom Buildings and Comfort Stations

Restroom buildings and comfort stations must be treated the same as other types of structures in Zone 

V and must meet the same elevation and design requirements as other buildings, even when the facilities 

are situated in public parks or recreation areas.

7.9 Swimming Pools and Spas

Three primary considerations relate to the placement of 

swimming pools and spas under or adjacent to buildings in 

Zone V:

• Whether the pool or spa will cause increased flood

loads on buildings or exacerbate scour and erosion near

buildings.

• Whether the pool or spa configuration is subject to

NFIP use limitations for enclosed areas under elevated

buildings.

• Whether a removable enclosure is placed around a pool

or spa (usually in the winter) that will cause increased

flood loads on buildings or exacerbate scour and erosion

near buildings. NFIP flood insurance treats these

enclosures as permanent enclosures even if they are only

used seasonally or for short periods of time.

Pools, pool decks, and walkways that are placed under or adjacent to coastal buildings must be structurally 

independent of the buildings and their foundations and must not contribute to building or foundation 

damage during the base flood. Three options, also recognized by ASCE 24-14, Section 9.6.2, satisfy this 

requirement:

• The pool can be elevated so the bottom of the lowest horizontal structural member supporting the

pool (and the pool itself) is at or above the required flood elevation, or

SWIMMING POOLS AND SPAS

Pools and spas adjacent to coastal 

buildings are allowed only if they will 

not act as obstructions that could 

lead to damage to nearby buildings. 

This effectively means that most 

pools and spas must be installed 

in-ground (either frangible or 

immovable) or completely elevated 

above the BFE. Swimming pools, 

spas, and related equipment are not 

covered by NFIP flood insurance.
NFIP TECHNICAL BULLETIN 5 MARCH 2020 45

• The pool can be designed and constructed to break away without producing debris capable of 

damaging nearby buildings, or

• The pool can be designed and constructed to remain in the ground and not divert flow or waves that 

can damage nearby buildings.

Registered design professionals must certify that pools or spas beneath or near buildings in Zone V will 

not be subject to flotation or displacement that will damage building foundations during a base flood or 

lesser event. In cases where pools are empty part of the year, flotation calculations should assume that 

pools are empty. Figure 28 shows a spa that was displaced and likely caused the failure of two piles that 

supported an elevated deck.

Figure 28:

Failure of two piles supporting an 

elevated deck that was likely caused 

by movement of a spa

The NFIP permits swimming pools and spas beneath elevated building only if the top of the pool or spa 

and accompanying deck or walkway are flush with the existing grade and the area around the pool or spa 

remains unenclosed. However, some states and communities may prohibit or restrict unenclosed pools 

and spas beneath elevated buildings. Designers should check with the local jurisdiction for any additional 

requirements.

The NFIP limits the use of enclosures under elevated buildings to parking of vehicles, building access, 

and storage. Because pools and spas do not satisfy these limitations, they are not allowed to be enclosed, 

even if enclosed by glass or breakaway walls. Use of lattice and insect screening is permitted around pools 

and spas below elevated buildings.
46 NFIP TECHNICAL BULLETIN 5 MARCH 2020

8 References

This section lists the references cited in this Technical Bulletin. Additional resources related to NFIP requirements 

are provided in Technical Bulletin 0.

ASCE (American Society of Civil Engineers). 2005. ASCE 24-05, Flood Resistant Design and Construction. 

Available at https://www.asce.org/.

ASCE. 2014. ASCE/SEI 24-14, Flood Resistant Design and Construction. Available at https://www.asce.org/.

FEMA (Federal Emergency Management Agency). 2005. Mitigation Assessment Team Report: Hurricane Ivan in 

Alabama and Florida. FEMA 489. Available at https://www.fema.gov/sites/default/files/2020-08/fema_489__

hurricane_ivan_bpat_.pdf.

FEMA. 2009. Local Officials Guide for Coastal Construction. FEMA P-762. Available at https://www.fema.gov/

media-library/assets/documents/16036.

FEMA. 2010a. Home Builder’s Guide to Coastal Construction: Technical Fact Sheet Series. FEMA P 499. Available at 

https://www.fema.gov/media-library/assets/documents/6131.

FEMA. 2010b. Substantial Improvement/Substantial Damage Desk Reference. FEMA P 758. Available at https://www.

fema.gov/media-library/assets/documents/18562.

FEMA. 2011. Coastal Construction Manual: Principles and Practices of Planning, Siting, Designing, Constructing, and 

Maintaining Residential Buildings in Coastal Areas (Fourth Edition). FEMA P-55. Available at https://www.

fema.gov/media-library/assets/documents/3293.

FEMA. 2012. Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures. FEMA P-259. 

Available at https://www.fema.gov/media-library/assets/documents/3001.

FEMA, 2014. Primary Frontal Dune Fact Sheet. Available at https://www.fema.gov/sites/default/files/documents/

fema_primary-frontal-dunes_fact-sheet_5-24-2021.pdf.

FEMA. 2017. Protecting Building Utilities from Flood Damage. FEMA P-348. Available at https://www.fema.gov/

media-library/assets/documents/3729.

FEMA. 2018. Answers to Questions About Substantially Improved/ Substantially Damaged Buildings. FEMA 213. 

Available at https://www.fema.gov/media-library/assets/documents/169099.

FEMA. 2019. National Flood Insurance Program Flood Insurance Manual. Available at https://www.fema.gov/

flood-insurance/work-with-nfip/manuals.

FEMA. Various. NFIP Technical Bulletins. Current editions available at https://www.fema.gov/

nfip-technical-bulletins:

Technical Bulletin 0, User’s Guide to Technical Bulletins
NFIP TECHNICAL BULLETIN 5 MARCH 2020 47

Technical Bulletin 2, Flood Damage-Resistant Materials Requirements for Buildings Located in Special Flood 

Hazard Areas

Technical Bulletin 4, Elevator Installation for Buildings Located in Special Flood Hazard Areas

Technical Bulletin 9, Design and Construction Guidance for Breakaway Walls Below Elevated Buildings Located in 

Coastal High Hazard Areas

ICC (International Code Council). 

ICC. 2012. 2012 International Building Code. Available at https://codes.iccsafe.org/category/I-Codes.

ICC. 2012. 2012 International Residential Code. Available at https://codes.iccsafe.org/category/I-Codes.

ICC. 2014. 2015 International Swimming Pool and Spa Code. Available at https://codes.iccsafe.org/content/

ISPSC2015?site_type=public.

ICC. 2015. 2015 International Building Code. Available at https://codes.iccsafe.org/category/I-Codes.

ICC. 2015. 2015 International Residential Code. Available at https://codes.iccsafe.org/category/I-Codes.

ICC. 2018. 2018 International Residential Code. Available at https://codes.iccsafe.org/category/I-Codes.

ICC. 2018. 2018 International Residential Code. Available at https://codes.iccsafe.org/category/I-Codes.

Rogers, S.M., Jr. and D. Nash. 2003. The Dune Book. North Carolina Sea Grant Report SG-03-03.

USACE (U.S. Army Corps of Engineers). 2002 and updates. Coastal Engineering Manual. Available at https://

www.publications.usace.army.mil/Portals/76/Publications/EngineerManuals/EM_1110-2-1100_Part-06.

pdf?ver=2014-03-10-135408-527