A key differentiator between window brands is the materials they are made of. When it’s your reputation and quality of work that is on the line, materials matter. Performance is indicative of what the window is made of, and those materials will also be a direct factor in how long they will last. No windows are stronger, more durable and require less maintenance than fiberglass windows, so it is in your best interest to recommend them to your customers. They significantly outperform vinyl windows and are less expensive than clad wood windows. You owe your customers the option of better quality, longer lasting fiberglass windows.

  • Not Bothered by Water: Because fiberglass is impermeable to moisture, there’s no concern about rot, corrosion, mold or shrinking and swelling.
  • Temperature Stable: Neither heat nor cold will induce fiberglass to flex, sag, or change dimension. That reduces chances of leaks around window perimeters.
  • More glass, less frame: The stiffness and strength of fiber-reinforced resins means that window frames and sashes can be narrower and less bulky without compromising their ability to resist high winds.
  • Value: On average, fiberglass windows run about 25 percent more than vinyl and about half the price of aluminum-clad wood.
  • Longevity: Warranties against construction defects range from 10 years to “lifetime” or for as long as your customer owns the house. Insulating glass typically carries a 20-year warranty against seal failure.
  • Low maintenance: Very low maintenance outside of cleaning the glass and replacing the weather stripping every decade or so.

Award-Winning Marvin Fiberglass Windows

Voted Best Fiberglass Window Brand for Excellence and Longevity every year since 2014 by BUILDER Magazine

“At Marvin, we didn’t just join the fiberglass windows and doors industry – we pioneered it. In 1994, Ultrex was born from The Marvin Companies’ century-long heritage of service, craftsmanship and quality with a focus on all-out performance.” – Susan Marvin

The Ultrex Advantage

  • 8 times stronger than vinyl
  • The only AAMA 624-10 verified finish
  • Expands and contracts at virtually the same rate as glass

The facts prove it. Ultrex fiberglass is eight times stronger than vinyl and three times stronger than vinyl/wood composites. It resists fading, chalking, peeling and cracking, giving you unparalleled strength and durability. We’re constantly testing Ultrex to prove it’s the toughest window material on the market.


Marvin Best Quality Fiberglass Window

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