Shandy Heil, Attaway, Denise, Baker, Eugene, Bankston, Jr., Joseph D. | 2/24/2009 2:23:51 AM
Garage doors create another opening homeowners should take care to protect. Because garage doors are so big, usually the single biggest opening of a house, and because most old doors are so weak, the survival of a house’s garage door is very important to the survival of the house. Owners of older houses have seen that when garage doors fail in hurricane winds a lot of additional damage follows.
Older garage doors and new ones that are not pressure rated are highly susceptible to wind damage, including buckling, twisting off the tracks and failure due to impact from windborne debris. Doors can be pushed in by winds blowing onto the door or pulled out as winds whip around the corner of the house where the door is located.
Failure of the garage door allows the full fury of the hurricane to act on interior walls, doors, ceiling or roof that form the barriers between the inside of the garage and the rest of the house. This frequently leads to failure of these surfaces and can lead to significant loss of roof sheathing or loss of a part of the roof.
Water intrusion around the perimeter of a garage door is not usually a big problem unless you have things that can be damaged by water sitting directly on the floor. Most garage floors are slopped towards the door so that water that blows in around the door will tend to drain out of the garage; however, in a hurricane winds may blow water into the garage for some time so it is probably prudent to raise vulnerable contents off the floor and away from the door.
One of the simplest solutions is to replace the door and its tracks with a door that is code approved for both wind pressure and impact protection (about $1,500 for a door wide enough for two cars). When you install a wind- and debris-rated door, your worries are over. The door is always there to provide the needed protection. When you are selecting a door there are two primary considerations: be sure the door is rated for the correct wind pressure for the design wind speed of the area in which you live, and select a door, at additional cost, that is also debris rated. Such a door will give you the ultimate in protection and is not an indulgence, but instead a prudent choice. Be sure to have door installed by a certified installer -- a strong door incorrectly installed will fail.
Another solution is to protect the garage door with a shutter or screen product that is rated for both wind pressure and debris impact. Storm panels are a very effective and easy way to protect a garage door because they are effective and are relatively easy to deploy. If your door is relatively new then storm panels may be the best route. On the other hand, if the door is deteriorated and is or will be in need of replacement, then replacing the door with a storm-rated door will be most cost effective in the long term.
Usually the only effective way to shutter a garage door is to install panels or a system that attaches along the top and bottom of the door opening.
Vertical bracing: Vertical bracing systems can be effective for supporting the door against wind pressure loading and at least one company makes a retrofit kit, with vertical members, that has Florida Building Code approval. Details are available at the Florida Department of Community Affairs Product Approval Web site.
Horizontal bracing: Horizontal bracing with wood members is rarely very effective and usually not a good idea. Sixteen foot and wider garage doors are big structural elements. They are so wide that it is not easy to make them strong. If you have looked at wind-rated doors you may have noticed that the manufacturers have usually installed several bars across each panel and they may have provided posts to further strengthen the door. It takes really hefty wood members to span the width of a two car wide garage door and make it much stronger. Permanently installing wood members to the garage doors will change the balance of the door and can make it so heavy that the garage door operator does not have the power to lift the door (human or motor power.
Adding posts that are installed after the door is closed can make a door stronger because the posts serve the purpose of making the door structurally narrower. Not only do door panels have to be strong enough to meet the design pressures; but, the tracks, the rollers for the wheels, the wheels, the axils for the wheels, the mounting of wheels to the doors, hinges connecting the doors, and the mounting of the track to the face of the house have to all be stronger than on older doors.
Do it yourself: The only do-it-yourself options that seem to make sense are to add vertical support posts. You can buy one of the kits for bracing the door as suggested above or install your own wood columns. You can install the posts at the center of the door (this will cut the forces on the tracks in half but the supports will have to carry half of the forces on the door) or possibly one-third of the way in from each edge of the door (this will reduce the loads on the tracks by two-thirds and the loads on the supports will be two-thirds of what they would be with a single center post). You will need to add pairs of supports, one on the inside and one on the outside at each location where you choose to brace the door. The tables shown here can be used to choose the size of the wood columns you would need to install and the strength of the anchors you will need at each end of the column.
You will have to look at your particular garage door situation and then be creative in selecting the appropriate hardware to anchor the columns to the floor and to the header over the garage door. Simpson Strong-Tie and USP both make hardware that has the kinds of capacities you will need to anchor the ends of the columns. The first table lists column sizes and forces for homes located in a normal suburban area where you are surrounded by houses and trees. If your home is located on the edge of a large field, lake or golf course, you should use the second table to identify the size and type of wood to use in the columns. All wood for the columns is assumed to be Number 2 grade (something that is commonly available at lumber yards and some home improvement stores). Southern Yellow Pine (SYP) wood is stronger than Spruce Pine Fir (SPF) wood. The red squares indicate that SYP lumber must be used. The black squares indicate that none of the common lumber is strong enough for the required bracing strength.
Keep in mind that even if you brace the garage door, you are not protecting it from damage from windborne debris. If you have a wooden garage door with panels, debris may knock out the panels and create a large opening for wind and rain.
Always use products that have been tested and approved to one of these standards and have been designated as such through a recognized product approval system or evaluation report: SSTD12; ASTM E 1886 and ASTM E 1996; or Miami-Dade Protocols TAS 201, TAS 202, TAS 203.
Institute for Business and Home Safety
American Architectural Manufacturers Association
FEMA Against the Wind
Federal Alliance for Safe Homes (FLASH)
Division of Emergency Management
Hurricane Retrofit Guide