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
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
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
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.