Schedule a Free Consultation

What Is Fibrex?

Renewal by Andersen® replacement windows feature frames and sashes made of an exclusive composite called Fibrex®. Combining the best features of traditional wood and vinyl frames, Fibrex outperforms other window replacement frame materials in terms of energy efficiency, durability and even visual appeal.

How Fibrex Is Made

In 1958, our parent company Andersen Corporation began research into a better alternative to existing frame materials. At the time, homeowners had to choose between aluminum, wood and vinyl. Early into the research, aluminum was deemed inadequate because it conducts heat and corrodes easily. Wood has many desirable features, but is vulnerable to the effects of moisture and temperature extremes. Vinyl is low maintenance, but is nowhere near as durable or as stable as wood.

Fibrex was finally patented and introduced in 1991, after decades of research. It’s made of 40% wood fibers and 60% polymer. The wood fibers are sourced from the trimmings at Andersen’s wood manufacturing facilities. The waste wood is pulped, fully dried and bonded with polymer at a molecular level. The resulting composite is then put through extruders, hardened and used to build the frames and sashes.

What Makes Fibrex Superior to Other Materials?

Fibrex gives homeowners the best of both worlds: window frames with the exceptional strength and durability of wood, paired with the low-maintenance qualities of vinyl. It also more stable than any other window frame material. Fibrex windows can be installed by window contractors in polar or tropical climates and will never warp or crack. The inherent strength of Fibrex allows for slimmer frames, which translates to more glass and a better view.

Fibrex complements our High-Performance™ Low-E4® glass packages with its natural insulation. It does not require an insulated core, yet it helps reduce thermal transfer. Fibrex frames help reduce your home’s indoor heating and cooling requirements, resulting in energy savings. The low-maintenance colors and finishes available with Fibrex will never require repainting, are warranted not to blister, peel or crack.

Renewal by Andersen of Spokane is your leading provider of window and patio door replacement services. Give us a call at (253) 604-1268 or fill out our contact form. We serve customers in Spokane, WA, and nearby areas.


"We had originally had the installation scheduled for mid-August, but had mentioned if they could do it sooner, that would be great. A cancellation led to us getting our 7 windows replaced almost a month early. The crew, which started out as 2, Tyler and Robert, arrived at just about 8 AM. They got to work immediately, were courteous, professional and wasted no time getting to the project at hand. Later in the day, another crew showed up because they had fewer windows to install a block or so over and got finished early., Chris and Adam, and suddenly everything was in fast forward. The entire job was finished before about 4PM, I think. They cleaned up and we discovered that something may have been vacuumed up as they went along. I was amazed that they actually emptied the vacuum cleaner bag and we found the missing objects (part of a master model that had gotten knocked down as WE prepared for the windows to be installed.). The crew went above and beyond by looking for the small plastic parts in that vacuum cleaner bag. I know, when we are ready to replace the remaining windows, we will be calling on this same company! They are awesome, efficient and friendly, yet very professional. Very pleased with everything they did, and the windows are beautiful, and functional, and we can already feel a difference in the house."

Debra Bird

View All Reviews