Many people assume when they buy a high-end window, which has for example, a Design Pressure Rating of DP50 (50psf), that they’re getting a window capable of standing up to the weather associated with windstorms, even hurricane force winds. Some of the windows are even labeled with “Hurricane Rated” tags, but the fine print reads much differently. In theory, its true, the DP50 rated window is designed to take those wind loads. But unless you’ve bought the expensive impact rated version, you’re windows are completely vulnerable to breakage from wind borne debris.
And even if you do fork over the extra money for the “Hurricane Rated” impact resistant feature, you are still purchasing a window, which is designed to allow water leakage to occur once wind driven rain velocities exceed 55mph. The reason for this is that AAMA (American Architectural Manufacturers Association) sets the water penetration standard to which most manufacturers adhere to be only 15% of the design pressure. There are practical reasons for this low standard relating to manufacturing difficulties and cost. Fifteen percent of DP50 is 7.5psf, is roughly equivalent to 54.6mph. A fairly routine wind velocity for wet winter storms?
Many people will never notice their windows leaking since small volumes of moisture seeping around and through the window frames are absorbed into the wall cavity framing, sheathing and insulation. Needless to say, this is ideal for mold and mildew growth within the wall cavity.
Having a shuttering solution like engineered storm panels or roll down shutters for your home’s glass areas can stop wind driven water from causing damage and can also extend the life cycle of those windows.