FRB Protecting Utilities and Ductwork

Protecting Building Utilities and Ductwork from Flood Damage
Background: A community must be fully compliant with the National Flood Insurance
Program’s regulations in order to obtain or keep its Community Rating System (CRS)
classification. Sections 60.3b(4) and 60.3c(2) of the NFIP regulations (44 CFR Part 60) require
communities to ensure that the lowest floor of any new residential building is elevated above the
base flood elevation. These regulations can be found at:
http://www.access.gpo.gov/nara/cfr/waisidx_00/44cfr60_00.html
The freeboard element (FRB) in Activity 430 (Higher Regulatory Standards) of the CRS
provides up to 300 points for requiring buildings to be protected to a level higher than the base
flood elevation. Many model ordinances and many locally adopted ordinances have freeboard
provisions. These are usually found in the ordinance as a “regulatory flood elevation,” a “flood
protection elevation,” or a “base flood elevation plus (1) foot.” It is called the “design flood
elevation” in this paper.
A problem arises when local regulatory officials focus only on the lowest floor, and neglect other
parts of their ordinances where there are additional provisions required by the NFIP regulations.
Sections 60.3a(3)(ii) and (iv) of the NFIP regulations require that buildings “(ii) be constructed
with materials resistant to flood damage” and “ be constructed with electrical, heating,
ventilation, plumbing, and air conditioning equipment and other service facilities that are
designed and/or located so as to prevent water from entering or accumulating within the
components during conditions of flooding.”
In short, protecting a building from flood damage means more than elevating the lowest floor
above the regulatory flood elevation. Flood insurance claims have shown that the Federal
Emergency Management Agency (FEMA) has paid a lot of money for damage to air
conditioners, furnaces, ductwork and insulation that were flooded, even though the building’s
lowest floor was high enough. In addition, mold, mildew and fungus accumulating in flood
damaged air passageways often can lead to serious health issues for residents.
This is primarily a concern for buildings on
crawlspaces. Buildings on slab foundations, on
pilings, and in V Zones normally have the utility
facilities waterproofed or elevated high enough.
The new FEMA Elevation Certificate highlights this
problem. When properly completed, the surveyor
must record the elevation of the “top of the bottom
floor,” “attached garage,” and “lowest elevation of
machinery and/or equipment servicing the building,”
among other things. If the attached garage,
machinery, and equipment are not above the base
flood elevation or are not otherwise protected from
flood damage, then the building is not in compliance
with the NFIP regulations.

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Focusing on elevating only the lowest floor
misses other items subject to flood damage.

November 2002

What’s required: To receive full CRS credit for Freeboard (FRB), electrical, heating,
ventilation, plumbing, and air conditioning equipment and other service facilities (including
ductwork) must be elevated or waterproofed to the base flood elevation plus freeboard. To be
fully compliant with the minimum requirements of the NFIP, this equipment and service
facilities (including ductwork) must be elevated or waterproofed to the base flood elevation.
A community can receive 75% of the appropriate FRB credit if it requires the utility facilities
(including ductwork) to be elevated (or appropriately waterproofed) to or above the base flood
elevation, but not necessarily to the freeboard level. If the utilities and ductwork are not elevated,
floodproofed, or otherwise protected to the base flood elevation, there is no credit for FRB. Four
scoring scenarios are shown below. In the top two, if the ductwork is not watertight and made of
flood-resistant material, the building is not compliant with the NFIP regulations.

FEMA Guidance: Protecting Building Utilities from Flood Damage, FEMA 348, reviews ways
to protect utilities and ductwork. This is the text from page 3.1-14 on alternatives to elevating
ductwork. It can be found on FEMA’s website at http://www.fema.gov/library/pbuffd.htm.
“Component Protection
“The NFIP does not recommend locating duct work below the DFE [design flood elevation, i.e., the
base flood elevation plus freeboard] in any new or substantially improved structure located in an
SFHA [Special Flood Hazard Area]. There is no known cost-effective technique for designing air
ducts to keep floodwater from entering or accumulating within the system components during
inundation by floodwaters.

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“If duct work must be installed below the DFE, it should be minimized as much as possible. The
material used for the ducts must be impermeable and watertight, such as welded seamless ductwork
or large diameter PVC pipe. Such material is very expensive but practical for cases where a short
length of duct work descends below the DFE.
“The water and fuel piping associated with HVAC systems must be properly protected from damage
during flooding. PVC piping generally requires special consideration when used in flood-prone areas.
This type of pipe is more susceptible to impact breakage. In addition, the nature of the material
sometimes fractures or shatters when exposed to the heaving and settling that a structure experiences
when withstanding floodwaters. If the lines are ruptured, it may result in contamination, leaking, or
even fire. In general, copper and galvanized metal piping is better suited for use in flood-prone areas.
“Note: Component protection for duct work refers to continuous duct segments below the DFE
which are watertight and terminate above the DFE. Duct segments with openings below the DFE or
that terminate below the DFE are not permitted under the NFIP.”

What the community should do: The following steps are recommended to ensure that your
community is fully compliant with the NFIP and receives the appropriate freeboard credit under
the CRS:
1. Review your ordinance and verify that you have clear legal authority to require elevation of
ductwork and other utilities to or at the freeboard level. If in doubt, ask your community’s
legal counsel for a letter stating how the ordinance is to be interpreted.
2. Review your permit application and inspection procedures to determine the best way to
ensure that the requirement is being met. This may necessitate procedural changes such as
additional information on the permit application form, additional plans provided by the
applicant, an addition to a field inspection checklist, and/or a photograph for the record at the
time of the final inspection.
3. Discuss the matter with local builders and architects as necessary. Feel free to use excerpts
from this handout.
4. Make sure your permit records show that the building's ductwork has been properly elevated.
Here are some ways that this can be done:
a. If the ductwork is located above the first floor, it should be clearly shown in the building
plans.
b. The final inspection records could note that the ductwork is above the first floor or "X"
feet below the first floor. This measurement can be made by the inspector.
c. The final inspection records could include the actual elevation of the bottom of the
ductwork.
d. The finished construction elevation certificate could include the actual elevation of the
bottom of the ductwork in the comments part of Sections D or G.
5. Advise your ISO/CRS Specialist what your community will do. Will you need to change
procedures to verify compliance? Will you prefer to forego CRS credit and not require
ductwork to be elevated above the freeboard level? What will the ISO/CRS Specialist need
from you at your annual recertification?

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November 2002