But can it Pass a Missile Test?
Many hurricane prone regions are following the state of Florida’s lead and are requiring all buildings and their components withstand a certain amount of wind pressure. Wind loaded overhead doors generally are design to withstand from 90 mph to 150 mph wind speeds. These design wind speeds are dictated by local Building Departments.
In some areas you may be eligible for a discount on your home owners insurance if you install a wind rated garage door. However, your insurance company may require the garage door to have a Miami-Dade County certification.
Just because your garage door meets the wind load rating which is required for your area, it does not automatically mean the door carries a Miami-Dade County certification. Miami-Dade requires the door to meet 150 mph wind load, the door must be made out of 24 gauge steel or heavier, and the door must also pass a missile-impact-test. In this test a 2×4 is shot out of a cannon twice at the door and the garage door must still be able to operate afterwards. The difference in cost between a door which meets the code in your area and a door with a Miami-Dade certification may exceed what you will save on your homeowners insurance over a ten year period. Check with your insurance agent to determine the insurance company’s discount requirements if you wish to take advantage of this program.
Hurricane winds generate positive (inward) and negative (outward) pressures so not only does the door need to be braced to keep it from blowing into the garage but it also needs to be designed so the door does not get forced out of the garage. Backing your vehicles up against the door from inside has very little value and may result in your car being damaged, along with the door. Our recommendation is to always ask your pole building provider to include wind rated garage doors which already meet or exceed your local wind load requirements.
Hurricane Andrew proved that a non-wind rated garage door was one of the most vulnerable areas of a building.
After Hurricane Andrew crossed Florida in 1992, many studies concluded the overhead garage door was one of building’s weakest points. The loss of the garage door contributed significantly to the severe damage and catastrophic loss of many buildings by allowing enough air pressure inside to literally lift the roof up and off of the structure. Today’s new building codes are based on what was learned from this devastation.
Hurricane Charlie struck Florida in 2004 and proved wind load ratings for garage doors which were put into effect after Hurricane Andrew were effective in protection of homes, buildings and pole barns directly in the path of the storm. Literally thousands of non-rated garage doors were blown out of their openings. However, the 130 mph and greater rated doors stayed in their openings and continued to function afterwards. Granted some were damaged (dented) from flying debris but the opening and the structure remained protected. There were a number of cases where one of the doors which had been replaced with a rated door before the storm survived the storm without a scratch but the non-rated door(s) beside it which hadn’t been replaced left the building completely (some were blown into the mangroves & never found).
Do yourself and your garage (and everything in it!) a favor, don’t skimp on the doors. Wind rate them for over 130 mph so what is inside, stays inside, no matter what.