How to Build a Hurricane Safe Room

Locate your safe room in an interior space on a solid foundation. Pre-fabricated safe rooms are built to be bolted to cement slabs in a garage or inside the house. Look for a place to build yours where it will be surrounded by interior walls. Place it above tidal flooding limits and projected storm surges (figures available from FEMA). The foundations for safe rooms---and all housing foundations in coastal areas---should be above this "base flood elevation." Recommended specifications and construction choices, including foundation requirements, are outlined in detail in FEMA publication 550, "Recommended Residential Construction for the Gulf Coast: Building on Strong and Safe Foundations."

Build framing to exceed local standards. Find the wind and storm surge loads for your area. FEMA reports identify coastal areas as sustaining winds of 200 or more miles per hour in a maximum-force hurricane (Andrew's winds were 145 to 175 miles per hour as it raked Florida) but most codes require framing to withstand 90 to 150 mph winds. Safe room framing systems and beams should exceed Standard Building Code regulations written to meet "median" load requirements. Use pressure-treated 2-by-4-inch and 2-by-6-inch lumber to minimize splintering if the framing fails. Framing is discussed in detail in FEMA 281, "Mitigation Assessment Team Report: Hurricane Opal in Florida".

Support the roof. Attach 2-by-6-inch rafters across floor-to-ceiling framing with hurricane clips and lay a double layer of three-quarter-inch plywood over the rafters. A slanted "lean-to" roof will shed falling or blowing debris more easily than a flat roof. The roof might have to support or protect against falling trees and debris from buildings. Its construction also should exceed local building codes. Add ventilation fans or duct work with protected outlets in the roof to provide fresh air for occupants.

Provide for easy but secure entry and egress. Remember the scene in The Wizard of Oz where Auntie Em had to pull the storm cellar door open against the rising wind? Build your safe room with a sheltered door cove. Build a protecting wall around one side or in front of the door to protect occupants as they enter and exit. Use a steel door or attach steel sheathing to a door to present a smooth, protective surface to the wind. Add one-inch deadbolt locks to hold it tight in high winds that might warp the building and inset hinges on the door frame.

Cover the exterior with a smooth skin. Cover the framing with three-quarter-inch plywood and then cover the plywood with a solid, resilient covering from the roof all the way down to the ground. FEMA's materials list recommends 14-gauge steel sheathing attached with galvanized roofing nails. Properly applied and secured, solid sheathing denies winds a way to get under materials as it can with shingles and siding. The steel also adds a layer of strength over framework and keeps rain out.