Comapre Composite vs. Fiberglass Windows


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Composite vs. Fiberglass Windows

If you are comparing composite vs. fiberglass windows, here are four key areas that you should compare and contrast in order to get an idea of which material is the best for your replacement project. Many fiberglass window frames are actually composite frames. Many composite frames are a proprietary mix of vinyl and wood as is the case for the Andersen 100 window and Renewal By Andersen.

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On the strength front, composite materials and fiberglass windows will be quite similar. Fiberglass composites will be a bit stronger than a vinyl composite. The best answer is that it will depend on the model and upgrades selected for that particular window.


The overall look of fiberglass is an upgrade over vinyl, but is pretty similar to many composites. For instance, the Marvin Infinity is regarded as a very best looking fberglass windows, while the Pella Impervia does not get good marks for how it looks. The Andersen 100 composite and Starmark from Okna are regarded as nice looking windows, while the Amsco Renaissance is a cheaper model and can't really compete against these other models.

Energy Efficiency

Fiberglass is going to be more energy efficient over many composites. However, top performers like the Okna Starmark offers excellent performance numbers, which you will pay for. In the long term, fiberglass windows will be a better performing for your home and energy bills.

Costs & Value

Fiberglass will typically be a bit higher than composites - see our page on the best fiberglass windows to see some of the costs and prices for many of these models. Composites have a wider cost range that starts lower than their fiberglass counterparts.

Bottom Line

The bottom line on composite vs. fiberglass windows is that it's extremely dfficult to make generalizations because each composite is very specific to the company that manufacturers the windows. See our page on the best composite windows for pricing on some of the top models.

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