Window Selection – Fibrex® vs. Fiberglass

Living room with Ultrex® fiberglass windows

There are different types of materials used to make replacement window frames. The material you choose has a huge impact not only on the window’s aesthetics, but also on its performance and durability as well.

Fibrex® vs. Fiberglass – What’s the Difference?

Fibrex® is a composite material made up of 40% wood and 60% plastic. It is a thermoplastic material, which simply means it has the potential to change shape when exposed to extreme temperatures. Fiberglass is a type of fiber-reinforced plastic using glass fibers. More specifically, our focus is on Ultrex® fiberglass. Its proprietary acrylic finish is 3x thicker than the competition – one of the reasons it stands out above other fiberglass. This finish is paintable, fade-resistant, and virtually maintenance-free. In contrast to Fibrex®, Ultrex® is a thermoset material, which means that it is cured and hardened into a shape, like concrete.

Why the Window Frame Material Matters:

Fibrex® is 2x stronger than vinyl. Ultrex® fiberglass is 8x stronger than vinyl. The stronger the material, the thinner your window frames. The thinner your frames, the more glass/daylight coming into your home and bigger views from your house.

Fibrex® is a thermoplastic material. Ultrex® fiberglass is a thermoset material. Thermoset materials can’t be melted back down again, which means that windows and doors made of Ultrex® will not melt or lose their true shape, even when exposed to extreme temperatures up to 285° F.

Fibrex® and glass are made from two different materials. Ultrex® fiberglass and glass are made from the same basic material (silica sand). When your glass and window frame are made from the same material, they expand and contract at nearly the same rate, ensuring the windows stay tight and true and resistant to leaks, seal failures, and stress cracks.

As you can see, the most common similarities these two window frame materials have are in their spelling and phonetics. Beyond that, it is clear to see the differences between Ultrex® and Fibrex® replacement windows. Although this may be your first time replacing your windows, we want it to be your last, which is why we are Georgia’s exclusive dealer of the Infinity from Marvin Ultrex® fiberglass window. Call us today to start your project!

Fibrex® vs. Fiberglass chart pros and cons

1. Highest rate of thermal conductivity shown. Test results range from .10-.13 for vinyl/wood composite (Fibrex® ) and .09-.12 for Ultrex®.

Fibrex® is a registered trademark of Andersen Corporation. Ultrex® is a registered trademark of Marvin Lumber and Cedar Co., LLC.

Visit our showroom at: 1210 Warsaw Rd.  Ste. #1000, Roswell, GA  30076
770.888.1604  |

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