Material Choices

Window and Door Framing
The most common framing materials used for windows and patio doors are wood, vinyl, and aluminum. More recent introductions to the market include fiberglass and a number of composites. Manufacturers also combine materials commonly, producing vinyl- or aluminum-clad wood products, wood-clad vinyl products and other combinations to meet a variety of demands for performance and aesthetics.

Vinyl is the most commonly used framing material, because it offers good thermal performance and requires little maintenance. It can be used to produced very cost-effective products, but vinyl windows can also be provided in a choice of interior finishes, including woodgrains and colors. Most vinyl products incorporate rigid vinyl with multi-chamber profiles for strength and insulation. Frame and sash corners in these vinyl windows are generally welded, creating a joint that is generally more resistant to air and water infiltration than corners that are mechanically fastened with screws.

Vinyl window
Photo courtesy of ViWinTech
Vinyl cutaway
Photo courtesy of Westech Building Products

Wood offers good thermal performance and natural beauty. Many manufacturers offer products in a wide variety of species. Wood requires maintenance that other materials may not, in that it might needs to be painted or stained periodically. Most manufacturers of wood products offer a choice of aluminum and/or vinyl cladding on the exterior to minimize such maintenance requirements. Increasingly, wood window and door manufacturers are incorporating "engineered" wood components, particularly in non-visible areas, to enhance performance and achieve optimal wood utilization.

Wood window
Photo courtesy of Andersen Windows

Aluminum is stronger than wood or vinyl. For this reason, it is still the dominant choice in architectural and demanding commercial applications. Its strength also allows framing widths to be minimized, allowing for larger glass areas in aluminum windows and doors. Aluminum itself is a good thermal conductor; therefore most aluminum window manufacturers offer "thermal-break" products. In these designs, a structural insulating material is incorporated between the interior and exterior aluminum.

Aluminum window Photo courtesy of CGI Windows & Doors

Fiberglass offers strength comparable to aluminum and insulating properties similar to wood and vinyl. It can be provided in a variety of finishes and generally can be repainted in the field. Fiberglass framing cannot be bent, however, which means these types of products are generally not available in round-top, elliptical, and other specialty models.

Window with fiberglass on the exterior and wood on the interior

Photo courtesy of Integrity Windows & Doors


Other Materials are also used by a select number of manufacturers. These include steel, cellular PVC, thermoplastic alloys, engineered plastics, and wood/plastic composites. These materials can provide enhanced performance and/or aesthetics. A number of manufacturers, for example, use composite materials to offer a look closer to a wood window along with the low maintenance features of vinyl.

Composite window
Photo courtesy of
MI Windows & Doors

Cutaway of a composite window
Photo courtesy of Amsco


Door Materials
Within the industry, door panels without any framing are referred to as "slabs." Residential entry door slabs are primarily manufactured in wood, insulated steel, and fiberglass. Vinyl entry doors are also available, as are doors produced with other composite materials. Sliding glass doors and many hinged glass models are also produced in vinyl and aluminum. Interior doors are most commonly made of wood. The most common feature a hollow core and a molded door face or skin.

Wood-Traditional wood doors feature "stile-and-rail" construction. Vertical stiles and horizontal rails are joined together with solid wood panels (or glass lites) to create a single door panel. Today, stile, rail and panel pieces are often made up of "engineered" wood. This is done to enhance performance and/or achieve optimal wood utilization. Manufacturers offer doors in a variety of wood species.

In addition to traditional stile-and-rail construction, a variety of other methods are used to manufacture wood doors. The most common type of interior door is constructed with molded (or flush) high-density fiberboard skins. These are offered in a variety of designs (re-creating the look of stile-and-rail construction). Another option for interior applications is MDF (medium density fiberboard) doors. These doors use solid pieces of engineered wood that is routed to create patterns.

Wood stile-and-rail door Photo courtesy of Kolbe & Kolbe Millwork Co., Inc.

Interior door with fiberboard skin
Photo courtesy of Craftmaster Manufacturing


Cutaway of engineered wood door section
Photo courtesy of Huber Engineered Wood

Steel-Most entry or exterior doors sold today are steel. A steel door slab features an interior and exterior steel skin on both sides of a core made up of an insulating foam surrounded by a wood perimeter to provide energy efficiency. Steel door slabs are produced in a variety of solid panel styles (again, recreating the look of stile-and-rail construction). Steel door slabs often have a section cut out and replaced with a door lite (or a decorative glass panel). Steel doors are available in stainable versions to offer a woodgrain look.

Insulated steel entry door
Photo courtesy of Masonite International

Cutaway of steel door section
Photo courtesy of Huber Engineered Wood


Fiberglass-It has been around for many years, but fiberglass had recently seen a tremendous increase in popularity in the exterior door market. Constructed similarly to steel doors, the fiberglass composite skin in place of steel, these types of doors are also designed to provide good energy efficiency and low maintenance. They are now offered in a growing number of stainable/paintable woodgrain and paintable smooth panel options. One advantage of fiberglass is said to be higher resistance to dings and dents.

Fiberglass entry doorPhoto courtesy of Plastpro


Glass, of course, is the most common material used in windows and doors. Today, in addition to ordinary clear glass, most manufacturers offer a variety of high-performance and decorative options. Check out our Energy Efficiency page to see links to a number of detailed sites providing information on low-emissivity (low-E) and solar-control glass, how these products work, and selecting the right options for you. Check out our Safety/Security page to learn more about window and glass options that provide impact-resistance for enhanced protection from hurricanes, as well as greater resistance to break-ins and other threats.


Recent introductions to the market are low-maintenance and self-cleaning glasses. Glass manufacturers have recently introduced new coatings that can limit dirt build-up on the exterior and reduce the need for cleaning windows on the outside.

Low maintainance versus ordinary glass
Photo courtesy of Gorell Windows & Doors

Window Styles Door Styles
Specialty Window Shapes Material Choices
Safety and Security Energy Efficiency
Finding a Quality Product Maintenance, Repair and Replacement
Industry-Related Organizations