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How a Window Manufacturer Can Help Determine the DP Rating for High Impact Doors and Windows

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As of May 21st, 2020, the NOAA Climate Prediction Center had predicted a 60% chance of experiencing an above-normal Atlantic hurricane season. The department prepared citizens for 13 to 19 named storms, of which 6 to 10 could become hurricanes, and 3 to 6 may turn to major hurricanes. When it comes to hurricane preparedness, many condo owners have already caught on the drift, but if you just erected a high-rise building, you got a thing or two to learn.

Hurricanes are notorious for causing damage in many regions around South Florida. Hurricane Irma, for example, was the most powerful hurricane in history records. Ranked as a Category 5 storm, it spawned wind speeds of 185 mph, causing an estimated $50 billion in damage with high-rise building hit hardest. It explains the need to install hurricane proof windows and doors designed to provide year-round safety from such harsh weather conditions. Finding the best window manufacturer isn’t enough; it’s imperative to understand how impact doors and windows are rated to choose the right ones for your building. This brief should help you:

Design Pressure Rating

High impact glass windows and doors are designed with upgraded frames and hardware, as well as thick glass usually sealed with strong adhesives. They should have a design pressure rating that shows they have gone through rigorous pressure tests to ensure they can hold up to dangerous storm conditions. The rating is a function of three factors: structural load, water, and air infiltration. The high the DP rating, the better the window’s or door’s resistant to the benchmarks.

A window manufacturer begins by performing an air filtration test, which involves simulating the amount of pressure the windows can tolerate. Note, the test doesn’t impact the design pressure rating of the window, but the structural and water infiltration test does. The water penetration test helps determine the amount of rain the door or window can keep out based on its DP rating. Thus, hurricane glass doors with a DP of 50 has been tested at 7.5 PSF.

Structural tests, on the other hand, examine the glass and frame of the door or window. As such, a window with a high DP rating means that the glass is thicker, and the hardware is made from high-end material. Hurricane proof windows are usually tested at high pressure than what the actual pressure level is. This means if a window that has a DP rating of 30 is rated to hold up to wind speeds of 110mph, they can withstand higher wind speeds up to 170 mph. The high the DP rating, the better the resistance to the said benchmarks.

Performance Grade Rating

Note, DP ratings only need to meet two out of three components during tests. Some window manufacturers misrepresent the ratings by using a higher number to show the effectiveness of the product. Performance Grade rating was developed; as a result, to encourage accurate representation of a product’s efficiency. This means impact glass doors or windows with a PG rating should meet all the three requirements, which include water infiltration, air infiltration, and structural load.

How to Read the Ratings

A window manufacturer categorizes high impact door and windows based on its ability to hold up to a certain hurricane category. There are five hurricane categories:

  • Category 1: 74-95mph
  • Category 2: 96-110 mph
  • Category 3: 111-129 mph
  • Category 4: 130-156 mph
  • Category 5: 157+ mph

If a window manufacturer has decided to use a 10-point difference in DP rating to be equivalent to the hurricane level, then a window with a DP rating of 30 should survive Category 3 hurricane. Note, the ratings withstand sustained winds; they don’t factor in tornadoes, wind gusts, and projectiles that accompany hurricanes. Every year, the Atlantic hurricane season runs from June 1 to November 30. The best way to prepare for this season is by safeguarding your property by installing hurricane resistant windows.