Types of Materials Used in Replacement Windows

Window frames are available in a variety of materials including aluminum, wood, vinyl, fibrex, and fiberglass. Frames may be primarily composed of one material, or they may be a combination of different materials such as wood and vinyl. Each frame material has its advantages and disadvantages.

Aluminum. Though ideal for customized window design, aluminum frames cause conductive heat loss (i.e., they have low R-values) and condensation. However, thermal breaks made of insulating plastic strips placed between the inside and outside of the frame and sash greatly improve the thermal resistance of aluminum frames. 

Wood. Wood produces higher R-values, are unaffected by temperature extremes, and are less prone to condensation, but they require considerable maintenance in the form of periodic painting. If wood frames are not properly protected from moisture, they can warp, crack, and stick. 

Vinyl. Vinyl windows are made primarily from polyvinyl chloride (pvc), which offers many advantages. They are available in a wide range of styles and shapes, have moderate to high R-values, are easily customized, are competitively priced, require low maintenance, and mold easily into almost any shape. 

Fiberglass. Fiberglass is relatively new and not yet widely available. They have the highest R-values of all frames; thus, they are excellent for insulating and will not warp, shrink, swell, rot, or corrode. Fiberglass frames can be made in a variety of colors and can hold large expanses of glass. Some fiberglass frames are hollow; others are filled with fiberglass insulation. 

Fibrex. Fibrex material is a blend of wood fiber and specially formulated thermo-plastic polymer. This unique window material is made from reclaimed wood fiber from the Andersen Window Corporation's 65 acre manufacturing operation in Bayport, Minnesota. Fibrex combines excellent strength, insulation properties and provides low maintenance.

Common Types of Windows

Single-Hung/Double Hung In double-hung units, both sashes slide vertically. Only the bottom sash slides upward in a single-hung window. Ventilation area can vary from a small crack to an opening of one-half the total glass area. Screens can be placed on the exterior or interior of the window unit.
Casement Casement windows are hinged at the sides. Hinged windows such as casements generally have lower air leakage rates than sliding windows from the same manufacturer because the sash closes by pressing against the frame. Casement windows project outward, providing significantly better ventilation than sliders of equal size. Because the sash protrudes from the plane of the wall, it can be controlled to catch passing breezes, but screens must be placed on the interior side.
Awning Awning windows are hinged at the top and open outward. Hinged windows such as awnings generally have lower air leakage rates than sliding windows from the same manufacturer because the sash closes by pressing against the frame. Screens are placed on the interior of the window unit.
Bay Window A bay window is made up of three or more windows. The side or flanker units project out from the building in 30, 45, or 90 degree angles. The center is parallel with building wall and is made up of one or more windows. All the units can be stationary, operating, or any combination thereof.
Bow Window A series of four or more adjoining window units, commonly five in number, installed on a radius from the wall of the building.
Fixed Frame Refers to windows that are non-venting or inoperable.
Skylight A window installed in a roof and assuming the same slope. Depending on which direction they face, skylights can bring in more light and heat than windows. For example, in the summer months, an unshaded south-facing skylight will bring in more direct sunlight and heat than a window. In a cold climate, a north-facing skylight gives almost five times more light than a north-facing window with almost the same amount of heat loss.
Slider Both sashes slide horizontally in a double-sliding window. Only one sash slides in a single-sliding window. Ventilation area can vary from a small crack to an opening of one-half the total glass area. Screens can be placed on the exterior or interior of the window unit.