What Can Impact Windows & Doors Withstand: Understanding Coastal Ratings

Coastal storms certainly exceed a typical windy rain shower, and it’s no surprise that these extreme weather conditions call for a different caliber of window and door solutions.

June 8, 2017

Homes on the coast or in hurricane impact zones demand stronger protection against the elements, so it’s important to understand impact-resistance, impact ratings and other measures for creating a shield against extreme conditions. When it comes to the harshest coastal conditions like hurricane force winds, driving rain, humidity, flying debris and endless sun, window and door products must be specifically designed to take a beating while still preserving a home’s structural seal—and its beauty.

What are Impact Resistant Windows

Many don’t know that the primary reason a house collapses in a storm is that when the windows break, air pressure inside the house increases. This additional pressure lifts the roof and can bring down the walls. Consequently, the glass selected for windows and doors can be the most important factor in salvaging a home in a heavy coastal storm.

Impact-resistant windows are designed to withstand strong forces of nature, and are rigorously tested to ensure they perform. Impact-resistant glass generally consists of two laminated glass layers with an interlayer that helps stop flying debris. Even if the glass shatters in place, the laminated layers preserve the overall structural integrity of the window. An additional benefit of impact-resistant glass, as compared to hurricane shutters or traditional plywood barriers, is that impact-resistant glass is protection that’s built in—working for your home 24/7 without any intervention needed.

How is impact-resistance measured? Products with impact-resistant glass are rated for their ability to withstand wind speeds in various, predetermined wind debris zones called Impact Zones, or IZ for short. Areas prone to hurricanes and storms involving high wind speeds are categorized into four zones, each with their own building code certification standards. Many Marvin Coastal Solutions products are rated for the highest wind areas, including IZ3 and IZ4.

Thanks to technology that’s constantly evolving, impact-resistant glass and IZ-rated products are an option for many different types, sizes and colors of windows and doors—meaning that choices aren’t necessarily limited in terms of the aesthetic look a homeowner wants to achieve. Homeowners in even the strongest wind zones can access taller and wider windows and scenic doors, like the Ultimate Multi Slide Door from the Marvin Signature Collection, to take advantage of beautiful views and indoor/outdoor living when the weather is mild, while maintaining protection when it’s not.

Design Pressure (DP) and Performance Grade (PG) Ratings

When you’re told that a window meets a specific “DP” or “PG” rating, what does the rating actually mean? DP stands for “Design Pressure”—a calculation that takes the wind load or the wind pressure of a particular site into consideration. Essentially, Design Pressure is a performance specification for how strong a window is, expressed in how many pounds per square foot (psf) of pressure the window can withstand. The Design Pressure required for a home will vary based on location, and in coastal areas, will be considerably higher.

“PG” stands for “Performance Grade.” A product only achieves a performance grade rating if that product complies with all requirements of the North American Fenestration Standard/Specification for a certain design pressure and maximum expected wind speeds where the home is being built. Performance Grade goes a step further in also verifying structural performance, water penetration resistance, air infiltration resistance, uniform load deflection, forced-entry resistance, operating force and durability tests. Sound like a lot? It is. Window and door products with a high PG rating have earned it with a battery of tests.

These are terms and ratings that your building professional or window dealer should be an expert in, and they can help ensure window and door selections meet any building codes or requirements in your area.

Effects of Sun and Salt on Window and Door Hardware

The strength of the glass isn’t the only consideration for homes in harsh coastal regions. The exterior window finish and hardware are constantly exposed to sun, heat and salty air—meaning that products not particularly manufactured to retain their color and finish in these conditions may fade or rust.

Marvin’s aluminum extruded cladding goes through a 5-step pre-treatment process to provide retention of color and gloss. A high-performance Kynar finish features Fluropon® with 70% PVDF (polyvinylidene fluoride—a polymer that has high purity and resistance to solvents) that provides superior resistance to fading from UV rays, and chalking due to a breakdown of paint. Marvin hardware is also available with a PVD (Physical Vapor Deposition) finish—a state-of-the-art process that resists fading and discoloration due to sunlight, humidity and other coastal conditions. Hard-wearing metals are vaporized and then deposited onto brass or brass-plated handle substrates for increased toughness and durability.

Turtle Glass for Coastal Homes

Even the turtles in coastal regions have different needs—and bright reflections from glass windows and doors that face the ocean can complicate the turtle hatching process.

Many Marvin Coastal Solutions products can be specified to meet Sea Turtle Conservation Codes, which help to reduce the light and reflection that can confuse sea turtle hatchlings. Thanks to this code, hatchlings get less disoriented and are more likely to find their way to the sea.

Why Coastal Windows and Doors?

If you’re living or building a vacation home in a coastal region, it’s important to understand why not all windows and doors are created equal when it comes to providing adequate protection against the elements. Your building professional or window and door dealer can help you navigate technical terms and find the right products to meet the building codes in your area. However, being armed with basic knowledge of coastal window and door attributes, and performance ratings, can help you better understand the recommendations you’re receiving—and can help you weed through products that might talk the talk, but not walk the walk when it comes to coastal performance.

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