By Rich McCoy
As you look to replace your old windows in the Tampa Bay Florida area. You have to look at an important but often overlooked item and that is design pressure.
The American Architectectural Manufacturers Association (AAMA) defines Define Pressure (DP) as “A rating that identifies the load induced by wind and any other dynamic pressures”. The higher a DP rating the more resistant it is to the effects of wind and other pressures.
Design Pressure was instituted in the 1940”s by a group of window manufacturers and engineers concerned about hurricanes and other types of severe weather systems. The intent was to measure how a variety of building products performed in these types of conditions. The design pressure tests were designed to measure wind loads and how resistant windows would be to different types (severity) of storms.
National building codes now require testing and certification of windows. Windows and sliding glass doors must meet the requirements of industry standards that include air, water and structural testing. Impact tests must also meet cycle tests.
The design pressure is both positive and negative. Imagine you are driving on the expressway driving 70 miles per hour closely behind a large semi-trailer that is its backdraft and that also the negative. When you go to pass and you break away from the backdraft and feel the on rush of air that is the positive.
So now that we know what it is, why is it important to us? Well with the incorrect DP the force of the storm could damage the seals on the windows allowing air and water to blow through. Imagine the interior of your home being flooded and full of debris after the hurricane leaves because your window had the wrong DP. That is why a correct Design Pressure is important.
Thanks to Ken Brenden 2010 article in DWM magazine “Back to Some Basics”