Home Builder’s Guide to Coastal Construction
FEMA 499/June 2005
Technical Fact Sheet No. 29
Purpose: To identify the special considerations that must be made when
installing utility equipment in a coastal home.
Key Issues: Hazards, requirements, and recommendations
Special considerations must be made when installing utility systems in coastal
homes. Proper placement and connection of utilities and mechanical equipment can
significantly reduce the costs of damage caused by coastal storms and will
enable homeowners to reoccupy their homes soon after electricity, sewer, and
water are restored to a neighborhood.
Coastal Hazards That Damage Utility Equipment
--Standing or moving floodwaters
--Impact from floating debris in floodwaters
--Erosion and scour from floodwaters
Common Utility Damage in Coastal Areas
Floodwaters cause corrosion and contamination, short-circuiting of electronic
and electrical equipment, and other physical damage.
Electrical – Floodwaters can corrode and short-circuit electrical system
components, possibly leading to electrical shock. In velocity flow areas,
electrical panels can be torn from their attachments by the force of breaking
waves or the impact of floating debris.
Water/Sewage – Water wells can be exposed by erosion and scour caused by
floodwaters with velocity flow. A sewage backup can occur even without the
Fuel – Floodwaters can float and rupture tanks, corrode and short-circuit
electronic components, and sever pipe connections. In extreme cases, damage to
fuel systems can lead to fires.
Elevation of utilities and mechanical equipment is the preferred method of
Basic Protection Methods
The primary protection methods are elevation or component protection.
Elevation refers to the location of a component and/or utility system above the
Design Flood Elevation (DFE).
Component protection refers to the implementation of design techniques that
protect a component or group of components from flood damage when they are
located below the DFE.
NFIP Utility Protection Requirements
The NFIP regulations [Section 60.3(a)(3)] state that:
All new construction and substantial improvements shall 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
Utility Protection Recommendations
--Limit switches, wiring, and receptacles below the DFE to those items required
for life safety. Substitute motion detectors above the DFE for below-DFE
switches whenever possible. Use only ground-fault-protected electrical outlets
below the DFE.
--Install service connections (e.g., electrical lines, panels, and meters;
telephone junction boxes; cable junction boxes) above the DFE, on the landward
side of interior piles or other vertical support members.
--Use drip loops to minimize water entry at penetrations.
--Never attach electrical components to breakaway walls.
--Attach plumbing risers on the landward side of interior piles or other
vertical support members.
--When possible, install plumbing runs inside joists for protection.
--Never attach plumbing runs to breakaway walls.
--Install HVAC components (e.g., condensers, air handlers, ductwork, electrical
components) above the DFE.
--Mount outdoor units on the leeward side of the building.
--Secure the unit so that it cannot move, vibrate, or be blown off its support.
--Protect the unit from damage by windborne debris.
--Fuel tanks should be installed so as to prevent their loss or damage. This
will require one of the following techniques: (1) elevation above the DFE and
anchoring to prevent blowoff, (2) burial and anchoring to prevent exposure and
flotation during erosion and flooding, (3) anchoring at ground level to prevent
flotation during flooding and loss during scour and erosion. The first method
(elevation) is preferred.
--Any anchoring, strapping, or other attachments must be designed and installed
to resist the effects of corrosion and decay.
American Society of Civil Engineers. Flood Resistant Design and Construction
(SEI/ASCE 24-98). (http://www.asce.org)
FEMA. NFIP Technical Bulletin 5-93, Free-Of-Obstruction Requirements for
Buildings Located in Coastal High Hazard Areas.
FEMA. Protecting Building Utilities From Flood Damage. FEMA 348. November 1999.