Window Frame Materials

Windows come in a number of different frame and glazing types. By combining an energy-efficient frame choice with a glazing type tailored to your climate and application, you can customize each of your home’s windows.

Improving the thermal resistance of the frame can contribute to a window’s overall energy efficiency, particularly its U-factor. There are advantages and disadvantages to all types of frame materials, but vinyl, wood, fiberglass, and some composite frame materials provide greater thermal resistance than metal.

Multiple parameters of each window frame material presented in the comparative table below:

Material Thermal Resistance Durability Maintenance Cost Recycled Content
Wood very good variable high high low
Vinyl or PVC very good good* low low very low
Aluminum bad** good very low low typically > 95%
Steel medium superior very low high > 98%
Fiberglass very good very good* very low high medium


* Vinyl and fiberglass frames perform well in accelerated weathering tests. Because vinyl is not as strong as other materials, some vinyl frames are reinforced with metal or composite materials to improve their structural strength.

** Modern aluminium window frames are typically separated by a thermal break made of a polyamide. This greatly increases thermal resistance, while retaining virtually all of the structural strength.

Composites may combine materials to obtain aesthetics of one material with the functional benefits of another.

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Download our Free eBook The Ultimate Guide to Replacement Windows

There are many window companies out there to choose from when you need new windows for your home or business. So many, that finding the right information online for what you need can be difficult. There are many different window manufacturers that provide varying frames, glass types and prices that it can be hard to weed through everything on your own. My goal in writing this guide is to help you navigate through the process of finding the right style of window, for the right price, from the right company.