When considering the three most common window replacement frame options in the Phoenix market, vinyl, Fibrex® (Andersen’s composite), and fiberglass, Infinity from Marvin’s Ultrex fiberglass frame has quite an advantage. It is a thermoset which means it becomes permanently hard and rigid when heated or cured and that process is irreversible. Vinyl, which is 100% PVC plastic, and Fibrex® are thermoplastics. Thermoplastics
have the property of softening when heated. The softening will make the frame weak with constant glass pressure weight. Ultrex is 8x stronger than vinyl and 3.5x stronger than Fibrex®.
The other tendency with thermoplastics is thermal expansion. Thermal expansion is the continual expansion and
contraction with the frame as fluctuations in temperature take place. This will create warping, sagging, cracking, and air leakage. Infinity from Marvin’s Ultrex is as stable as the glass it supports.