Garage doors invite wind
Unless your doors have been installed after new building codes in 2002, your home may be threatened. Retrofitting and new doors are options to consider.
By JUDY STARK
Published April 17, 2005
You nailed plywood or screwed in metal shutters over your windows when Charley, Frances, Ivan and Jeanne rampaged through Florida in 2004. But what did you do about your garage door?
Hear this statement from the Federal Alliance for Safe Homes: "Approximately 80 percent of residential hurricane damage starts with wind entry through garage doors."
Think back to the pictures of the Panhandle or Punta Gorda: homes with garage doors blown out.
"The larger the door, the more vulnerable it becomes to high winds," said Jeff Burton, building codes manager at the Institute for Business and Home Safety in Tampa. "A double-wide is more vulnerable than a single."
Garage doors are vulnerable because they cover a big opening. Most garage doors are made of relatively lightweight galvanized steel, with or without polyurethane or polystyrene insulation, to conserve expense and make them easier to raise and lower. (Garage doors may also be made of aluminum, fiberglass and wood.) Because of that size and weight, the garage door is one of the weakest points on a building. Compounding the matter, garages tend to be at the corners of the house, where wind pressure and suction are at their greatest.
Homeowners have a couple of options.
NEW DOORS. First, look at your existing door. If it was installed after the new building codes went into effect on March 1, 2002, it should meet the requirements for wind load in your area. A label or certification seal on the door will indicate this.
If it's an older door, you can have a new door installed that meets hurricane codes. The requirements vary depending on which wind zone you're in. A retailer can help you determine which door is right for where you live. A door must withstand higher wind load along the beaches (and therefore will cost more) than one that's installed in inland Hillsborough County. A builder's-grade steel door that meets Hillsborough hurricane standards might cost $800 to $1,000.
Even then, you're not buying guaranteed safety. If the framing members of your garage "aren't up to code as far as how they're attached to the structure, having a wind-loaded door could be all for nought," said Andy Kernaghan, operations manager at Overhead Door in Tampa. The strongest door in the world won't help if the garage is flimsily constructed.
RETROFITTING EXISTING DOORS. Retrofitting an existing door involves strengthening the panels, tracks and rollers to withstand the wind - what a new door would do. Garage door repair companies can do this for you, or you may be able to find a retrofit kit that you can install or have someone install for you.
When high winds swirl around the house, they exert both pressure and suction on that big expanse of door, which is held in place only by the tracks. So your goal is to reinforce the door and the tracks, Burton explained. You don't want the door to be sucked out of the tracks, and you don't want the tracks to pull out of the ceiling or wall to which they're attached.
Retrofitting involves giving a door rigidity against pressure and suction, Burton said. U-shaped metal struts or bracing attach horizontally and vertically onto each panel of the door. But bracing the door is only part of the task.
Kernaghan, of Overhead Door, recommends adding long-stemmed rollers. The shaft, or stem, on the roller is longer so that if the door does flex in high winds, the roller won't pop out of the hinge.
He also recommends adding brackets to hold the track to the wall so it won't give way easily.
Adding struts, reinforcing the track, replacing the rollers and recalibrating the springs would cost about $300 for a double-wide garage door, Kernaghan estimated.
"We can add the struts to each section to reinforce the door, but can I give you a document that says it's rated for this type of wind? No, I can't," Kernaghan said. Reinforcing an existing door "means you've done what you could with an existing older home and an older door."
You may decide that the cost of retrofitting an existing door would be better applied toward the price of a new door, suggested Ted Signor, whose Largo garage door company bears his name.
When high winds assault a garage door, it buckles in the middle in a V. The rollers pop out of their brackets and the door fails, Signor explained. Horizontal and vertical struts and sturdier rollers and brackets strengthen the door and transfer the windload across the door to the garage structure. "The whole ideas is: Take the load from the wind off the door and transfer it to the building," he said.
Signor discourages his customers from installing garage doors with windows, which may be broken by flying debris. Then the wind can enter the garage, regardless of how strong the door is.
Garage door springs contain a huge amount of stored energy. An out-of-control spring can be dangerous or even deadly. This is one of those jobs that may best be left to the experts. Simply attaching plywood to the inside of the door may void the warranty or damage the motor or the track because the door is too heavy to operate properly.
The trade association for garage door manufacturers issues this caution: "Owners should avoid adding reinforcement to a garage door themselves. This will increase the weight of the door and may result in failure or collapse of the supporting tracks or other components that may not be suitable to carry the extra weight. Upgrading garage doors by adding reinforcement must be performed as a package that includes appropriate springs and hardware and supporting track."
There are also removable posts that can be attached to a plate in the garage floor and to a header above the door. When a storm is about to make landfall, someone has to be available to put the post in place and run cables from the door to the post to prevent the door from flexing. These cost about $150 plus installation.