Fiberglass Windows in Richmond, VA

Pultrusion is a continuous process: glass-fiber strands and mat are soaked in resin and pulled, rather than pushed, through a heated die that sets one constant profile. The result is a hollow frame piece that the NFRC's consumer guide calls strong, durable and dimensionally stable. HomeGuide says fiberglass expands and contracts at nearly the same rate as the glass it holds. That is the core technical case for it, because the glass edge seal and glazing tape aren't being flexed every hot afternoon. Corners are usually joined with brackets or screws rather than welded, and HomeGuide notes that some fiberglass windows leak more air than welded vinyl as a result. Read the air-leakage figure if the label lists one, not only the U-factor.

These hybrid units bond a wood inner face to a fiberglass exterior, a design the NFRC guide describes as split-sash. You get stainable wood inside, where it sits next to old trim, and a shell outside that never needs scraping. They suit a dining room or study with stained casings. The interior wood still needs a finish, so ask whether it arrives raw, primed or prefinished, since that changes who does the work and when. Mixed frames are hard to judge by eye, which is why the NFRC guide points buyers to the whole-window label.

Fiberglass frames are usually painted at the factory, which opens up a far wider palette than vinyl, including black, bronze and deep greens. In our view, because the frame barely moves with heat, a dark finish on fiberglass is less of a gamble than dark PVC on a sunny wall. The tradeoff is the paint itself. HomeGuide notes a factory finish can fade or chalk over time and may need repainting. The upside is that fiberglass can be repainted to a new color later, which vinyl isn't designed for.

Fiberglass is stronger by weight than vinyl, so manufacturers can draw thinner frame profiles, HomeGuide says, and thinner frames mean more glass. That matters most on an insert, which already loses some glass because it nests inside the old frame. On the tall six-over-six windows of a rowhouse or Colonial Revival front, a slim meeting rail also reads closer to the original wood sash than a chunky one. One limit: fiberglass isn't among the materials Richmond's historic review guidelines accept in City Old and Historic Districts, so check the wood window restoration page before choosing it for a house in one.

Composite frames are not fiberglass, though sales sheets often file them together. They are wood particles and polymer extruded into frame lengths. The NFRC guide calls them very stable, with structural and thermal properties equal to or better than wood, plus better moisture and decay resistance. They can be painted, and some are textured to look like wood. HomeGuide puts composite windows at $400 to $2,300 each installed, in the same bracket as fiberglass. Ask the installer to name the frame material in writing so you know which one you're buying.