In the world of entryways, there are three basic material types available for residential exterior doors.
WoodAuthentic wood doors use stile and rail construction by joining multiple components to create an overall design that is architecturally correct and features defined details in and around the panels. Wood doors can be stained to enhance their natural beauty. Standard sizes for wood doors typically are 2'-6", 2'-8" and 3'-0" wide by 6'-8", 7'-0" and sometimes 8'-0" high, however they can be customized to fit any size opening. Although wood doors are quite durable, they are not the most energy efficient. As with all exterior products, they require maintenance and should be refinished annually to retain their beauty and avoid issues caused by moisture, especially in unprotected exposures. Standard construction doors can split and crack under high temperatures in addition to parts separating over time. However, when properly cared for, a wood door can last for many years.
FiberglassFiberglass doors are two large molded skins with a polyurethane foam core between the skins which is a great insulator against heat and cold. The fiberglass sheets, along with the foam core, do not absorb moisture and therefore eliminate the rotting, warping, peeling, and bubbling that can affect other exterior doors. Fiberglass doors mimic the grain of real wood doors and can be painted or stained. They are popular for their high insulation values, low maintenance, and resistance to dents and scratches. Premium fiberglass doors are architecturally correct like wood doors.
SteelIf aesthetics are not a priority and a budget directs the buying process, a steel door is a great alternative. Steel doors can be painted and feature the same polyurethane foam core found in fiberglass doors, therefore offering the same insulating protection against cold and heat. Steel doors will either be hot or cold to the touch depending on exterior weather conditions. Home-to-garage entryways are a prime example of where a steel door is a popular option. Steel doors are economical and offer good insulation, require low maintenance if placed in a fully protected exposure, and won't rot. However, steel doors are highly susceptible to rust and can easily dent.
There are pros and cons to selecting a wood, fiberglass or steel door, however understanding their construction in relation to the concept of exposure will provide you with the knowledge needed to confidently choose the correct door type for your specific exposure.