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How Much Wind Can Your Windows Take?

Courtesy of Wikimedia Commons
By Gates Dearen

It seems that whenever Hurricane Season rears its ugly head, that’s when Floridians start taking stock of their homes and gardens.  Since the past two years have produced named hurricanes that made landfall here in north Florida, it becomes all the more important that you survey your home looking for vulnerabilities that wind and rain can exploit.  Once you’ve had a chance to check your roof to see how much life your shingles still have in them, followed by your yard to see which trees need trimming, the next logical places to consider, are your windows.

Storm Warning
Before the next named storm comes knocking, take a good hard look at your windows.  They are the most vulnerable part of your home to wind and weather.  Even if a storm doesn’t pack wind sufficient to blow your windows out, older windows that don’t quite close completely or those that have cracked, or missing weather-stripping, are quite literally problems waiting to happen.  You may be surprised to know that the greatest damage that occurs during and after a hurricane is not caused by wind,  it’s caused by water.  A leaky window can do a great deal of damage to sills, sheetrock, carpets, and flooring.  If left unchecked, damp sheetrock is likely to attract mold.
How Much Wind is Too Much?
When it comes to wind, I am often asked just how much a window can take.  To that I reply, “It depends.”  A basic residential window typically can take a force equal to fifteen pounds per square inch before they lose the battle with the typical pressures of a major storm.  That being said, it doesn’t mean your windows can stand this much force.  Again, if the weather-stripping on your windows are old, cracked and/or brittle, it could take much less force to make them fail.  On the other hand, if you have newer double-pane windows, your windows could well withstand significantly more force than 15 PSI.

Courtesy of Wikipedia
With old windows, all you can do is guess.  With newer windows, all you have to do is examine the window’s technical performance data to find out how much wind the windows are designed to take.  The design pressure rating can be found on the manufacturer product data sheet.  If you can’t put your hands on the sheet, you can obtain the information by calling the manufacturer or the company that installed your windows.

Once you’ve obtained the design pressure rating, you can use some basic arithmetic to convert design pressure to the wind speed to learn the wind speed your windows are designed to withstand. Known as the Ensweiler formula, all you have to do is take the square root of the design pressure and multiply it by 20.016.  For instance, a window with a design pressure of 30 can take winds up to 110 MPH.  Those with design pressure ratings of 50 are designed to withstand wind speeds of 140 MPH.  So, choosing a pressure rating that can take a licking and keep on ticking in the kind of hurricanes that have been known to visit the Jacksonville area, should be fairly straightforward.

Is Wind the Only Thing You have to Worry About?
No. Of far greater potential to shatter a typical window during a storm is flying debris.  Wind speeds of 50 MPH or greater have the potential to pick up and hurl debris.  The faster the wind, the heavier the debris it can carry.  When you consider a Category 1 hurricane packs wind speeds of between 74 to 95 MPH, flying debris becomes a very real possibility.  While your windows might be rated to withstand 110 MPH winds, try telling that to a flying tree limb or a hunk of wood after it comes whistling through the air to smash your window.  
I have seen pictures of windblown 2x4s that have become embedded in stucco or been driven through a tree trunk during a hurricane.  I’m sure you have too.  While hurricane shutters or even plywood can help protect windows from windblown debris, they are by no means guaranteed to stop everything a windstorm can throw at them.

Impact Windows to the Rescue
Impact Windows Courtesy of
That’s why impact windows were invented.  Working something like a typical window on the outside and a bulletproof vest on the inside, impact windows derive their super strength from a sheet of transparent polymer material sandwiched between two glass panes.  Just like bulletproof glass, they’re designed to crack without shattering should a piece of debris come flying into them.  While impact windows cost a bit more than traditional windows, the amount of money they can save you during a single hurricane is considerable.  That’s because should even a single window in your home fail during a hurricane or any other storm, the damage to your home and furnishings could be very costly.  That doesn’t take into consideration the danger to your family should a window blow out during a storm.

If you want to find out how much hurricane windows cost, contact us at HomeRite Windows and Doors by calling (904) 296-2515 or visiting our showroom at 4801 Executive Park Court, Building 200, Suite 207, Jacksonville; FL 32216. 

Gates Dearen is the co-owner of HomeRite Windows and Doors in Jacksonville, Florida. He and Richard Walden have been serving the building products industry in Florida for over 25 years. They strive to match homeowners with the right windows and doors for their homes and budgets. They make the home improvement process pleasant with first-rate, energy-efficient products, affordable pricing, and award-winning installers who employ the best practices and who always treat customers and their property with the utmost respect.

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