Once regarded as a niche product with maybe 2% share of total U.S. window sales, a recent market report shows fiberglass with a 3.2% share of market that is continuing to grow.
Once regarded as a niche product with maybe 2% share of total U.S. window sales, a recent market report shows fiberglass with a 3.2% share of market that is continuing to grow.


Gary Stoley was strolling through the Pittsburgh home show early last year looking for a company that might replace the vinyl windows in his 20-year-old home. This April, Stoley had those windows replaced with fiberglass units, a product that — before the home show — he didn’t know existed. “We wanted windows that would last until we’re done with the house,” Stoley says.

Gaining Traction

Once regarded as a niche product with maybe 2% share of total U.S. window sales, fiberglass products have gained traction during the last few years. The most recent market report jointly released by the American Architectural Manufacturers Association and the Window & Door Manufacturers Association shows fiberglass with a 3.2% share of market, with 2.6% of remodeling/replacement. More contractors are installing them because more homeowners are asking for them.

“They’re looking for a product with longevity and durability,” says John Schmotzer, owner of Metropolitan Windows, in Pittsburgh, whose company installed the units in Stoley’s house. The strongest indication that fiberglass may have an even bigger role to play in window replacement is the entrance of siding manufacturer James Hardie into the business. In April the fiber-cement siding producer bought a fiberglass window extrusion plant.

Wood vs. Vinyl vs. Fiberglass

Window contractors who already sell fiberglass agree that James Hardie’s entry into the fiberglass window market can only make more popular a product that’s already finding favor with homeowners. Two factors have helped push fiberglass windows out of the niche category and toward the mainstream: More manufacturers — including Marvin Windows and Doors, Pella Corp., and Milgard Windows & Doors — offer fiberglass products, and more homeowners know about them.

Window Pro, a window replacement company in Middleburg Heights, Ohio, began carrying fiberglass windows in 2009. President Jake Zahnow says that the company mostly competes for a demographic he describes as “upper-middle” and above. “Two-thirds of the time they’re considering wood,” Zahnow notes. “The other third vinyl.” Generally, though, he adds, “those in the upper end tend to self-select themselves out of vinyl,” where price is often a first consideration and where the cost may be half of what a fiberglass window would go for.

Selling Points

Companies that offer both vinyl and fiberglass, or all three — wood, vinyl, and fiberglass — windows, see stronger interest in fiberglass. “I would say it’s now about 40% of our business,” says Scott Burns, co-owner of Next Door & Window, in Naperville, Ill., whose company started selling fiberglass windows 10 years ago. “We like selling it.”

A good way to do that, Burns points out, is by comparing fiberglass windows to fiberglass entry doors. Another selling point: The fact that because the window is, in effect, all glass, it comes without the frame expansion and contraction, which can cause vinyl windows to lose their dimensional integrity. We have never had a seal failure on fiberglass windows, Burns says.

Zahnow and other contractors who install fiberglass say that cost alone makes it unlikely that fiberglass will rival wood and vinyl in market share. “It’s not going to surpass vinyl and wood” in terms of numbers of units sold, Schmotzer says, but “it is becoming a product of demand.” Window dealers who carry fiberglass agree that James Hardie’s entrance into the market, by “giving credibility to the material,” could boost that demand. “If it’s 3.5% now, I can see [fiberglass’ market share] being 10% or 12%,” in the foreseeable future, Zahnow says. —Jim Cory is a contributing editor to REMODELING who is based in Philadelphia.