Design Pressure Ratings

Prior to starting the process of replacing your windows, you may have never heard of window design pressure ratings. However, now you know that your new windows need to meet a certain design pressure (DP) requirement depending on your location. 

What is Design Pressure (DP)?

As defined by the AAMA (American Architectural Manufacturers Association), WDMA (Window and Door Manufacturers Association), and the NFRC (National Fenestration Rating Council), design pressure is a rating that identifies the load – induced by wind and/or static snow – that a product is rated to withstand in its end-use application.

In most area’s the minimum requirement by Florida State code is a design pressure of 35 and as high as 60 in High Velocity Hurricane Zones (HVHZ).

This is the most abused code requirement in Florida.

How do you know what the proper DP rating should be?

A number of things are taken into consideration when the design pressure ratings are calculated, including geographic location, the height of the building and the location of that window in the building.

A home in Orlando, for example, may have a design pressure requirement of 35 because it’s in the center of the state, but a home in Miami could have a DP. With winds and potential hurricanes, the geographic location of the coastal homes requires a stronger DP.

Your local building department can assist you in determining what DP rating you need, based on the location and design of your home. Most municipalities have maps or easy-to-read charts that clearly explain the requirements you will need to meet in order to effectively protect your home with the proper Design Pressure.

If you’re working with a reputable, licensed and insured window installation company like FAS Windows & Doors, they should be able to help find the manufacturer specifications and verify the proper DR ratings.

FAS Windows & Doors has a three-step process to ensure the products you choose will meet the strict DP requirements:

1. Sales representatives carry laptops and use manufacturer specifications to verify proper DP ratings.

2. FAS Windows & Doors has a purchasing department to process all orders and double check the DP ratings by municipality per code requirement before ordering the desired product.

3. FAS Windows & Doors will pull a permit on all jobs.

There is a final check by the county before the permit is issued and verification that the correct products will be installed.

If a permit were not pulled, the homeowner would run the risk of getting caught and having to replace the products with products that meet code at their own expense.

Have more questions about DP ratings and permits?

Our team is here to answer any questions you may have. Visit our Tampa or Orlando showroom, or call today to schedule a free, no-obligation home consultation.


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Review Submitted on January 22, 2016, 04/24/2017
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