Build a Storm-Resistant Home

Although it's often advisable to evacuate before a major storm hits, you should still feel confident that your home will be there when you return.

PATH has studied how and why homes fail during hurricanes, and has learned how to properly and affordably build disaster-resistant homes. It all comes down to three key factors:

• Hurricane-force winds
• Wind-driven water intrusion
• Appropriate building materials

For example, PATH technology helped some homes in Port Charlotte, Florida, stand up to Hurricane Charley in 2004. The home pictured left was built with fiber-cement SIPs and suffered damage to one gutter, while other homes in the neighborhood were leveled.

If you are planning on building in a hurricane-prone area, make sure your builder addresses these considerations. They are a bit technical, but you should print out this page and go over each one of the recommendations to make sure you have as strong and safe a home as possible.

Note: Homes located in flood-prone areas should be designed with all living spaces located above the designated flood-plain elevation. If at all possible, do not build in a flood-prone area.

STRATEGIES TO IMPROVE WIND RESISTANCE

Cast-in-place concrete construction. Concrete construction withstands winds better than stick-built structures, and cast-in-place concrete walls are stronger than concrete masonry unit block.

Direct load path. Aligning the roof trusses with interior load bearing wall framing improves the up-lift resistance.

Hurricane straps. Line up bracing and tie-downs at critical load points to maintain the integrity of the load path. Use light-gauge steel straps to anchor the first story to the foundation. (During Hurricane Andrew, hurricane ties had a 92 percent success rate.)

Additional reinforcing. Added steel reinforcing around windows and sliding glass doors helps keep these units in place during high winds.

Proper nailing schedule. Size, type and placement are all factors. Nail edge distance tolerance is quite tight (acceptable nail edge distance should be 1/4 to 3/4 inch) and the nail overdrive can reduce uplift strength of the connection significantly. Thicker sheathing can offset sensitivity to overdriving.

Ring-shank nails. To secure sheathing panels in high wind-prone areas with basic wind speeds of 110 mph or greater, ring-shank nails are recommended for their higher withdrawal capacity. Costs are comparable, and with a slightly smaller diameter, they offer the added benefits of less frequent reloading of pneumatic nail guns and more forgiving edge distance tolerances.

Secondary roof covering. Peel-and-stick roof underlayment mitigates water intrusion if roof shingles are lost. These rubber or asphalt sheets cost $700 to $1000 more than standard roofing felt for a 2,400 square foot house.

Window shutters. Permanent or removable shutters reduce forces on the structure and minimize water- and wind-related damages to the interior by protecting windows. Storm-resistant shutters for a standard single-story home with 312 square feet of windows cost about $700.

STRATEGIES TO LIMIT WIND-DRIVEN WATER INTRUSION

PATH has evaluated homes hit by hurricanes, and has uncovered some surprising results:

• Wind damage accounts for only a fraction of the destruction
• The greatest destruction was caused by water infiltration, not catastrophic structure failure

Use baffled ridge vents and off-ridge vents instead of unbaffled vents. Unbaffled vents tend to allow wind-driven moisture to enter attic spaces or the cavities of cathedral ceilings, causing moisture damage and mold growth.

Install front doors so they swing out instead of into the house. Out-swinging doors are more resistant to wind loads, and they do a better job preventing water infiltration.

Use capillary breaks where concrete walls meet the slab. Capillary breaks suspends the flow of rainwater hitting the walls where they meet the concrete floor slab: preventing water infiltration through small cracks at the slab/wall juncture.

Apply elastomeric sealant at concrete walls. These finish coatings prevent water absorption during heavy storms. Pay special attention to seal at the wall's snap-tie locations.

Extend fascia board to terminate below the underside of the soffit. This helps keep water out of the eaves.

Install a natural-gas powered generator in the home. Homes subject to water infiltration can more easily prevent mold growth and rot if they dry out quickly. Generators allow fans and dryers to be used quickly after a hurricane, when electrical power is usually gone, often for extended periods.

BUILDING MATERIAL SELECTION

Building Materials: Construction materials should be resistant to damage from bulk water intrusion including floods and major rain events. Preferred building material attributes for flood-prone regions include:

Minimally or non-moisture absorptive. Select materials that will not absorb moisture. This will save you from having to do a major renovation if your home is damaged in a hurricane.

Ability to dry without long-term damage. If you cannot find non-moisture absorptive products, make sure that they can dry quickly, and without long-term damage.

Minimal or no voids within assemblies. Voids in assemblies more easily allow water to penetrate the home.

Integrated non-moisture absorbent insulation. Fiberglass insulation never dries, so it must be replaced after it gets wet. Select an insulation that does not absorb moisture, such as sprayed-foam insulation.

Affordable and market acceptable. A product can't be used if it isn't affordable or readily available.

These recommendations are based on Building for Survival in Hurricane Country, the PATH report Durability by Design, and lessons from a PATH site demonstration in Melbourne, Florida. In the Florida demonstration, a PATH team examined how to exploit the strength of poured concrete walls to enable homes to weather a major storm.

Content updated on 8/7/2006