What is Design Pressure:

Understanding design pressures are relatively simple. Design Pressures are the amount of pressure put on the openings (envelopes/windows/doors) during a hurricane. The pressure is caused by wind blowing on and around the subject property. As required by the Florida Building Code, every new window installed must meet a minimum design load/pressure. In most cases, an engineer does this for you. However in some instances, local building departments have charts such as the one below that they allow contractors to use instead of an engineer.

Example:

A standard impact sliding glass door or french door is called a 6’0-80″ which means it is 6 foot wide by 80 inches tall. Divide the 80″ height by 12″ which gives you 6.67 feet. Multiply 6.67′ by 6′ and you find that a standard impact door opening is 40 square feet (sqft). This is what you would use as the “Tributary Area”; then simply determine if your window is located in a Zone 4 or Zone 5 (middle or end zone), and you are done.

*Note this chart should be used only as an example and is NOT acceptable to submit for permitting.

Broward County: (954) 256-0030
Collier County: (941) 251-0030
Miami-Dade County: (305) 440-0030
Monroe County: (305) 330-5511