Rebuilding after Sandy: storm-resistant construction
Tom Shafer | Improvement Center Columnist | November 21, 2012
As Superstorm Sandy might have taught some homeowners, flooding from storm surge is not the only danger homes in coastal areas face from hurricanes.
The primary culprit for hurricane damage is often the updraft caused by wind: one of your windows or doors breaks open, wind fills the house, the roof lifts off and the walls fall down. If you live in a coastal region, you want your home's construction (or re-construction in the wake of the storm) to prevent updrafts from leveling your house. The Federal Emergency Management Agency, better known as FEMA, provides guidelines in its Home Builder's Guide to Coastal Construction for the sturdiest and most effective materials and construction methods for hurricane- and storm-prone areas.
7 ways to fortify coastal homes
The following list of seven home construction components includes products that meet the FEMA guidelines and are designed to help protect your home from coastal storms:
- Wood. In coastal areas wood framing should be capable of withstanding 72 hours in flood waters without sustaining major damage. Choose lumber pressure-treated to guard against rotting and deterioration caused by exposure to water, or use a natural decay-resistant species such as redwood, cypress or certain oaks. House framing should consist of 2-by-6 members instead of the usual 2-by-4 construction. The more substantial framing materials also add strength against the force of the wind.
- Sheathing. The material covering the studs -- the sheathing -- most commonly comes in 4-by-8 sheets, which means that they typically span only one story. Each additional story is sheathed with a separate set of panels. Norbord makes sheathing in a variety of longer lengths to cover more of the wall, so there is no break where the stories meet. That helps connect and hold the stories tight to each other.
- Fasteners. Normal construction techniques start with a sill plate bolted to the concrete foundation. Studs are nailed to the sill plate, and additional stories are constructed in much the same way until the rafters are added to form the roof. The components are fastened to each other with nails, screws and bolts. Metal tie downs -- such as those made by Simpson Strong Tie or USP Structural Connectors -- are simple galvanized strips that can be used to connect the foundation to the floors, the floors to the walls and the walls to the roof trusses. They help prevent damage from an updraft should one of the construction components fail.
- Windows. Window protection can be passive or active. Active types of window protection include boarding up windows with plywood or closing shutters. Passive protection is built into your windows and requires no additional action. Homes in areas where wind-borne debris is likely to occur should have impact-resistant doors and windows with laminated glass and special heavy duty hardware. To qualify as impact-resistant, windows and doors are tested to withstand penetration or against otherwise opening upon impact. Fastening windows to the house with 2-inch screws in specified places is another passive form of window protection, as is structurally anchoring mullions -- two or more windows joined together -- and fastening them to the headers and sills.
- Doors. Wind can enter the home through doors, so here, too, impact resistance is most important. The easiest and least expensive doors to make impact-resistant are solid, with no glass inserts. Glass can be used, but it must be laminated and pass testing. Therma-tru and Masonite sell doors that meet the requirements of the Florida building commission for use in high velocity hurricane zones, such as Miami-Dade county. The Therma Tru door has a steel plate inside the fiberglass panels to qualify. Proper installation is critical; fasteners must be spaced exactly as the manufacturer specifies.
- Siding. Even in thunderstorms, accompanying high winds can sometimes rip vinyl siding off the walls. The possibility is more likely in hurricane-prone areas. Consider fiber cement siding as an alternative exterior cladding. Its inherent strength makes it more stable in high winds, and its higher density is more resistant to impact. Make sure your builder follows the manufacturer's instructions for installation in high wind areas. Nails should be positioned near the ends of the panels following the manufacturer's recommendations for proper spacing. Do not use staples.
- Roofing. Some asphalt shingles are made especially for areas where impact and wind are present. Owens Corning WeatherGuard series of asphalt shingles are manufactured to withstand winds up to 130 mph, provided adequate fastening is used to prevent tear-off and water entry. WeatherGuard shingles should be installed using six nails instead of the usual four. This should be adequate protection for most tropical storms or moderate hurricanes.
Houses can be fragile when subjected to prolonged periods of intense wind, rain and storm surge. While you can't do much to control the weather, you can -- with proper construction techniques, durable products and by following manufacturers' installation instructions -- build a sturdier home, more capable of staying together in a severe storm.