Fiberglass window and door frames are essentially composed of glass fibers and resin, materials that expand and contract very little with temperature changes in the weather. Until recently, the complex profiles required for window designs have been impossible to attain with fiberglass. Innovation has made it possible to design a fiberglass frame and fiberglass windows and patio doors are becoming more popular among homeowners for its beauty and long-lasting durability.

Fiberglass windows and doors resist swelling, rotting and warping. The frame expands and contracts at approximately the same rate as the insulated glass it holds for improved energy efficiency and strength. While fiberglass frames do not require repainting for upkeep, the material is able to be repainted if you prefer to change colors.

The process Milgard uses to create their fiberglass window and patio door frame lineals is called pultrusion. Glass rovings and mats are pulled at tremendous forces through a resin bath and a series of dies. These materials combine and catalyze to provide tensile and torsion strength. Milgard regularly tests its fiberglass lineals for color uniformity, gloss, film thickness and chemical resistance for quality and long-lasting performance.

Double hung windows have two sashes that move up and down.

A single hung window  features one operational sash.