Letters to the Editor: Extreme Wind-load Questions
© 2005 Door & Access Systems
Publish Date: Fall 2005
Author: Tom Wadsworth
Pages 54-56
Letters to the Editor
Extreme Wind-load Questions
To the Editor,
I found the Extreme Field Test article (Winter 2004-2005) quite interesting. Many of us who don’t live in Florida tend to look away from such horrors hoping that such events never cross our doorway. I have several questions that may concern every door dealer across the country.
How do doors fail under extreme wind load? I assume that the door panel collapses, the rollers slide out, and the door is then blown into the building. Perhaps doors fail when the screws holding the track to the wall pull out. I suspect that any door dealer in southern Florida could answer these questions.
As I understand it, the wind-load requirements of the building code vary based on geographical location. A door installed in Omaha will not have the same configuration as a door installed in Boston. I believe that this factor should be widely broadcast to prevent the installation of the wrong product. How do manufacturers handle such wind-load issues with their dealers?
I believe that extremely wide doors are more prone to failure. Building extremely wide doors without proper testing or engineering will lead to failure and potential dangers. This is true for inland installations and not only for coastal regions. What is the maximum width for a sectional door?
What is the door dealer’s or door manufacturer’s responsibility when it comes to failure due to wind loading? Will insurance companies hold a manufacturer or door dealer responsible for damages? Will manufacturers blame the dealer for not fastening the components properly?
Alexander Timoschuk
Spec-Dor
Candiac, Quebec
Alexander,
To respond to your questions …
Door Testing. When garage doors are tested for wind resistance, they are installed vertically, as normal, mounted to the jambs with track brackets, and installed on a pressurizable wind chamber. The doors are then tested for positive and negative pressures, simulating (1) winds pushing the exterior of the door inward and (2) winds “sucking” a door outward. The tests are conducted frequently on a particular door to make sure the door can withstand repeated inward and outward pressures.
How to Fail. Doors can fail in a variety of ways. Causes of failure can be measured and observed ... such as too much bowing in the center, fastener failure (in track brackets), roller failure, or buckling of panels.
Varying Requirements. Yes, wind-load requirements vary. Many garage door manufacturers make a variety of doors to meet varying requirements. Tell your manufacturer your wind-load requirements, and they will likely have products that meet your needs.
In some markets, code requirements vary greatly. For example, coastal installations can carry requirements significantly higher than installations only 20 miles away inland. Further, code requirements vary depending on door size, building height, roof slope, and other factors.
On Maximum Width. Manufacturers engineer their doors for a variety of widths, heights, and models. Again, your manufacturer will likely know a particular model’s maximum width for your specific requirements.
Responsibility. If a door is improperly wind-loaded, and it fails in a wind event, it’s hard to predict who will be blamed. A successful partnership between a manufacturer and a dealer helps minimize product failures.
Manufacturers should be responsible for product design, quality, and integrity. Dealers should know the code in their area, choose the right product to install, and install doors according to the manufacturer’s written instructions.
Bottom Line: We must all work together as a professional, unified industry to (1) know the code requirements, (2) make doors to meet the code, and (3) install doors that meet the code. If you need further information, don’t hesitate to contact me or your manufacturer. We’re here to help.
Joe Hetzel, DASMA Technical Director
More Updates on Carriage-House Doors
To the Editor,
The summer issue was excellent, particularly the 2005 Carriage-House Sales Report. We’re surprised that many dealers have not yet discovered the advantages of the carriage-house door.
Many of our dealers have begun to change out doors in older subdivisions. One such dealer is changing out several doors in a 1988 project that is governed by a homeowners’ association. He just received approval to move forward based upon the two attached photos.
Many other dealers are having success selling the doors at the builder/architect level. Both the homeowner and builder recognize enhancing the curb appeal of a home’s exterior helps sell homes and create diversity within their neighborhoods. The steel raised-panel door has had just the opposite effect … all the homes and doors look the same, street after street.
We believe the popularity of steel raised-panel doors have hit their peak as carriage doors make their way into the marketplace. Hopefully, the dealers in our industry will recognize the importance of this event, and take full advantage of selling products that do more than close an opening. It will be interesting to see what the market looks like at this time next year. Future updates on your sales survey will be very beneficial for all of the industry.
John Jellá, President
First United Door Technologies
Tempe, Ariz.