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 plain; build with materials that tolerate soaking; and design the wall assemblies to easily dry when they become wet.

IBHS Fortified Home

The ASHRAE priorities may not be practical when retrofitting an existing house. Therefore consider using the Insurance Institute for Business and Home Safety’s (IBHS) FORTIFIED Home™  Hurricane Standards for upgrading  your house.  The IBHS FORTIFIED Home™ relies on an inspection to certified that your home meets one of three levels bronze, silver, or gold. Potential home insurance savings are available with each level.

Bronze Standard

The bronze standard for the FORTIFIED Home™ is focused on the roof. If the roof has less than five years life left it should be replaced. When replacing the roof, the existing shingles should be removed and the new roof should comply with the following:

  • the roof deck should be a minimum of 7/16” plywood or OSB,
  • attached with 8d shank nails spaced nominally at 6” on center or 4” on center for buildings within 600 feet of the ocean,
  • sealed with a qualified system such as a full layer of self-adhering polymer modified bitumen membrane. If the roof is asphalt shingles the membrane should be covered with 15# building felt,
  • a drip edge must be installed, and
  • the new roof covering must be high-wind rated and installed per manufacturer’s installation instructions.

If the roof does not need to be replaced, it can be structurally reinforced and sealed with closed-cell, polyurethane foam applied to the underside of each roof rafter or truss. Replacing attic insulation with closed-cell polyurethane foam at the underside of the roof deck solves other problems as well. It keeps hot humid air out of the attic, therefore creating a more efficient building envelope and heating and air conditioning system.

Silver Standard

The silver level builds on the bronze by certifying that all doors and windows are pressure and impact rated. If the existing opening do not meet the pressure and impact requirements you can protect the opening with qualified opening protection systems. This can be as simple as pre-cut 5/8” marine grade plywood or advanced as custom made hurricane shutters. The silver level also requires attached porches and carports to be properly connected to prevent uplift.

Gold Standard

The most advanced level, gold, includes stabilizing gable walls and installing connections to prevent uplift. The house will be tied together from the roof rafters to the walls, the walls to the floor, and the floor to the foundation.  Chimneys must also be properly attached to the building.

 

Another important preventive measure is to keep trees trimmed of dead wood. Dead wood is the first to become detached and a potential missile attacking the house.