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How is Fiberglass Produced?

What Makes Fiberglass Different than Similar Materials Such as PVC?

Fiberglass is one of the best materials to make windows out of, but you might not know very much about it, or anything about what sets it apart from what seem to be similar materials, such as PVC. Fiberglass is a common material found in products such as boats, chemical storage tanks, and swimming pools. While the overall process that creates fiberglass is similar in windows as it is in these everyday items, there are slight differences.


Fiberglass is actually a brand name of one of the materials properly referred to as fiber-reinforced polymers.

In the case of fiberglass, the substance doing the reinforcing is actually glass. The polymer is generally any durable, plastic-like material. The glass fibers are made by heating up sand to make glass in the traditional way. However, the molten glass is pulled into ultra-fine strands that will later be integrated into a polymer to make the fiberglass itself. What makes window fiberglass different from that in boats and other products is that fact that fiberglass windows are made from pultruded fiberglass. Pultruded glass fibers are pulled into strands, while other fiberglass pushes the glass through small holes to make strands.


Fiberglass is extremely versatile, as it is very strong but still able to be shaped easily.

Air is trapped within during its production, making it an excellent thermal and acoustic insulator. It can easily be clad with wood, to make an attractive window frame (though the wood will require additional maintenance, while a wholly fiberglass window would not). One of the reasons that fiberglass is such a good material for window frames is that is contracts and expands at nearly the same rate as the glass in the pane. This is a result of the glass fibers that it is composed of, and it prevents stress and structural damage.

NOTE: Just because a window is made of fiberglass doesn't guarantee quality. Make sure the manufacturer uses an insulated fiberglass frame rather than a hollow frame. Check out how they seal their corners and what kind of anchoring hardware these window manufacturers use.


Other Applications of Fiberglass:

  • Boats – 95% of the pleasure craft boating industry is dominated by fiberglass rather than wood and aluminum.
  • Recreational – Skis (water / snow), helmets, golf clubs, golf carts, hockey sticks, fishing rods, playground equipment, motor homes, snowmobiles, and swimming pools
  • Household Products – Shower stalls, sinks, bathtubs, microwave oven cook trays, television swivel stands, furniture, chairs and tables.
  • Automotive – Fender Moldings, front ends, head lamp and tail lamp housings, hoods, exhausts components, grilles, instrument panels, insulated tanks, engine covers and body components.
  • High Performance Products – Race cars, rocket motor cases, aircraft
  • Building and Construction – Windows, paneling, siding, skylights, curtain wall components, glazing panels, concrete pouring forms, ladders and painting poles.

Interested in replacing your drafty windows with durable, air-tight fiberglass windows? Find out which manufacturers offer fiberglass replacement windows or have a fiberglass window professional call you today!