Fiberglass frames are incredibly strong, thermally stable, and resistant to environmental
damage. Marvin and Pella both offer proprietary fiberglass products (e.g., Ultrex® and
Duracast®).

• Extreme Durability: Won’t warp, crack, or swell — even in harsh climates.
• Low Maintenance: Paintable, but won’t need it often.
• Energy Efficient: Low expansion rate helps maintain seal integrity over time.
• Clean Appearance: Sleek profiles available in a variety of colors.

Ideal for: Homeowners in extreme climates or those looking for strength and longevity with minimal maintenance.