Fiberglass on the Rise

While only 3 percent of the window market comes from windows made with fiberglass, the material is fast gaining a reputation for being durable and blissfully maintenance-free. Combined with its middle-of-the-road price, fiberglass provides solid value. It's stronger than vinyl, and fiberglass windows won't warp, rot or crack. Expect to pay about double the price of a comparable vinyl window.

Fiberglass windows are manufactured in limited colors, but they can be painted and the surface provides excellent adhesion. Some brands come in a natural wood exterior finish that does a great job of mimicking the real thing. Also available: real wood interior frames and sashes that can be stained.

On the green front, some manufacturers fill the hollow fiberglass frames with foam insulation to enhance the product's thermal performance. In addition, fiberglass is relatively easy to fabricate, so fiberglass products have a low embedded energy, meaning they don't require a lot of energy to produce.