Many people relocate to lowcountry from inland communities where there are not hurricanes. So often the first question a new resident asks is “What are the best practices for building in a hurricane prone area?”. Buildings need to simultaneously resist wind, rain, and flood.
The International Residential Building Code (IRC) made significant revisions after Hurricane Andrew that have been proven to prevent structural damage from wind. In fact, during the 2004 Florida hurricanes, no one died in any structure that was built under the revised code. The code requires that the building is tied together from the roof rafters to the foundation; the building is designed to withstand wind shear; the windows, doors, and skylights are protected from windborne debris; and the exterior finishes are securely fastened to the structure.
The success of the structural code changes highlighted the problem of rain entry into the building. Before when a homeowner was missing a roof, he was not concerned with a leaky window. Preventing rain infiltration is now a new focus in home construction. Many property insurance companies will give homeowners a discount for some of these best practices. The key items include: The roof needs an overhang to keep the rain off the building; provide sill pans under all windows and doors; flash all windows, doors and other penetrations; provide a drainage plane behind the exterior finish material to allow the water to escape and the wall to dry; provide a secondary roofing membrane; design closed crawl spaces that are dry and watertight; and drain the rain away from the house through the use of gutters and sloping the ground away from the building.
The U.S. Federal Emergency Management Agency (FEMA) has understood for several decades how to prevent flood damage. The basics are general common sense; elevate the livable space, floor structure and heating and air-conditioning ducts above the 100 year flood plane and the potential storm surge; install hydro-static vents to prevent flood waters from collapsing foundation walls; build with materials that tolerate getting wet; and design the walls to easily dry after they get wet.
The ASHRAE Guide for Buildings in Hot & Humid Climates recommends to design and construct buildings in hurricane prone areas using the following steps in order of priority: keep the building from blowing away; keep the rain out; elevate the structure above the flood plane; building with materials that tolerate soaking; and design the wall assemblies to easily dry with they become wet.