Pultruded Fiberglass Window Frames

Fiberglass window frames are becoming more popular as a product that offers several advantages over more common frame materials, including vinyl, wood, and aluminum. Fiberglass optimizes the dimensional stability and compatibility between the framing and the glazing. The profiles are made form saturating fiberglass fibers (about 60% fiberglass) in resin and pulling them through a thermosetting die to create the required profile, a process called 'pultruding' It also has other properties that make it an interesting addition to the residential and commerical window market. The main disadvantage of this product is the higher first cost. Below is a list of advantages and disadvantages of the product:

Advantages:
Coefficient of thermal expansion similar to glass (longer sealant life due to lower movement stresses on the seal)
Relative coefficients of thermal expansion:
Fiberglass: 7.4
Glass: 8.7
Aluminium: 23.0
Vinyl: 62.0
Dimensionally stable
High strength, rigid frame assembly
Low thermal conductivity (falls between typical softwood and PVC windows at the low-conductivity-end of the scale. Aluminum holds down the high-conductivity end of the scale, improved significantly with a thermal break)
Physical properties do not change through 350 F temperature cycle
Impermeable to moisture
Chemically inert
Frames can be insulation-filled to further improve thermal performance
Frames do not need (or have) thermal breaks to achive good thermal performance
Can be repainted, two-color painted finishes available for exterior/interior
Lowest embodied energy of window systems except wood

Disadvantages:
Higher installed cost
Limited manufacturers in certain parts of the country
Lack of industry acceptance
Accompanying storefront systems generally not available
Curtain wall systems not developed yet
Because of the two previous points, commercial applications that require windows, storefront, and curtain wall cannot be supplied by one manufacturer, so visual continuity of window systems may be a challenge to achieve
Anodized finish options not available, though metal-appearance finishes can be achieved
Color applied to surface, not through-color
Not readily field-fabricated yet

Related Materials:
Aluminum
Steel
Vinyl
Vinyl-clad wood
Wood
PVC

Applications:
Readily applicable to new residential construction, and commercial construction pending greater industry acceptance. Also used for replacement windows. Most manufacturers offer typical frame operating types - single hung, double hung, awning, casement, fixed and strip windows, patio doors and entrance doors. Recommended for harsh environments because of its inert and dimensionally stable properties and good thermal properties. As with any frame material, proper selection of sealants should take into account the material properties and manufacturer's recommendations.

AGB 9/2005