Why Fiberglass Windows?

Energy efficient frames have low conductivity that discourages the transfer of heat or cold into a building. Fiberglass windows have a much lower conductivity than metal options; simply placing a hand on a fiberglass window frame compared to an aluminum frame in -20°C weather makes the difference very clear.

Subjected to temperature extremes, fiberglass windows must remain stable, with minimal expansion and contraction to keep an excellent seal. Considering that the bulk of a window is glass, what better material to surround it with than glass? Hence “Glass on Glass Advantage”. Composed of about 60% glass, fiberglass, like plate glass, has a very low rate of expansion and contraction (see graph below). Fiberglass windows maintain an excellent seal with reduced movement relative to the plate glass. Superior stability also results in greater longevity, fewer seal failures, and better paint adhesion.

At 60% glass content*, the basis of fiberglass is silica sand, one of the most abundant naturally occurring materials available on earth. Fiberglass also has a very low level of embodied energy and requires only about 20-25% of the energy required to convert bauxite into aluminum.

Fiberglass also has a smaller impact on the environment due to its longevity. In a throwaway society, investing in durable products is becoming more and more vital. By choosing longer lasting, better quality products, we can keep more out of the landfills. DUXTON is an advocate of long-term sustainability, and believes in building for generations, not years.

Due to its energy performance and the nature of the material, fiberglass is often selected for Net Zero, LEED, and PassivHaus projects.

Fiberglass windows and doors offers significantly greater bend strength than PVC. Greater strength allows for slimmer frames, more glass area, and a better view. Even more valuable is that fewer frame divisions are required for large openings. Fiberglass windows can achieve stunning views with floor-to-ceiling glass that stretches across the length of the room. Bring the outside in!

Fiberglass windows and doors offer amazing colour flexibility. Unlike PVC which relies on light finishes, or exterior colour only, fiberglass offers endless colour options, inside AND out. The stability of the material allows you to select ANY colour, light or dark, standard or custom. Because fiberglass has a very similar application process to painting a vehicle, the finish is long-lasting and weather-resistant.

Fiberglass is an extremely stable material predicted to last about 40% longer* than PVC windows. It also provides a low-maintenance finish that is applied similarly to the way that a vehicle is painted, creating a weather-resistant, long-lasting finish.

Fiberglass has been specified for a wide variety of commercial projects, including recreational centres, financial institutions, and multi-storey towers. Its durability has been proven by schools in the far north, where windows are subject to abuse and very extreme temperatures.

Fiberglass is created with a combination of ultra-strong glass strands and glass matting. The glass matting that wraps around the glass strands assists in distributing any impact to the frame, preventing surface damage. In cases where the surface does become damaged, fiberglass can be repaired and re-painted.

The stability of the material assists in protecting, and prolonging the life of insulating glass. Because the fiberglass window frame has minimal movement relative to the glass and the wall, there is less risk of seal failure or glass breakage.

The cost of windows and doors can vary broadly depending on the brand and the quality of the components. Based on the quality difference, fiberglass windows typically costs more than vinyl windows. A select number of vinyl brands actually have similar pricing to fiberglass. Compared to metal-clad wood, fiberglass is often fairly comparable in price, but again, varies by brand.


The key consideration lies in the value proposition. Fiberglass windows are often the material of choice for architects and engineers due to its greater design flexibility, excellent performance characteristics, and longer lifespan. Given that an investment in windows is significant, it is worthwhile to invest in a higher quality product to put off a second replacement for as long as possible.

In commercial settings, fiberglass windows can cost somewhat more than basic non-thermally broken aluminum, but typically cost less than thermally broken aluminum – while having better thermal performance.


Due to the low conductivity of fiberglass windows, they do not need thermal breaks, and hence, the system requires fewer components. In addition, aluminum can have costly site labour requirements, whereas most fiberglass window systems can have significant labour transferred to the factory.


Whereas fiberglass is typically seen as a product for punched openings, it is being increasingly used for small- to medium-sized curtain wall applications due to its superior thermal performance.