French doors are manufactured in many styles, configurations, and sizes. The framing and mullions generally come in three basic materials: wood, fiberglass, and steel.
Wood. This is the most common material used for French doors because of its high-end look. Wood also allows for a softer yet rustic look and comes in many varieties that can be stained or painted. Wood is typically the most expensive material used for French doors because of its minimal maintenance requirements (though it should be repainted or restained every few years), and scratches can be easily repaired.
Hardwoods and softwoods have nothing to do with the actual hardness of the wood but rather differentiate between the microscopic composition and physical properties of each. Hardwood comes from deciduous trees, which produce either a fruit or a nut, have broad leaves, and generally become dormant in cold weather (though sub-tropical deciduous trees do not go dormant). Softwood comes from coniferous trees, which are for the most part cone-bearing evergreens that have needles.
Both hardwoods and softwoods have their own advantages and disadvantages. Some species are best used for exterior applications, while other types are exclusively for interior usage. Some are better for painting, others for staining.
* Poplar is an ideal choice because it accepts paints and stains well and is typically inexpensive.
* Red oak is the most popular and abundant of the hardwoods. It has excellent water resistance and will take more abuse due to its courser grain.
* Ash is slightly harder than red oak and stains well.
* Hickory is the strongest, heaviest, and hardest of the hardwoods. It looks best in a rustic application such as a log cabin.
* White oak is considered the best all-around wood and allows little or no water to penetrate its surface. It also offers excellent wear resistance and is highly stainable. White oak is commonly used on boats and in the making of wine and whiskey barrels.
* Cherry darkens with light exposure and also with age. It resists warping, and is hard, sturdy, and stains well. Cherry is sought after for use in furniture, cabinetry, and doors.
* Walnut is a tough, dark hardwood that sometimes has blonde streaks. Walnut stains to an exceptional finish and is second only to cherry as the choice for furniture, cabinetry, and doors.
* Mahogany is a tropical wood that is durable and will rarely warp. It is reddish-brown in color and has excellent finishing qualities.
Fiberglass. This man-made material has a clean, modern appeal and can be painted or stained. Due to the synthetic nature of fiberglass, doors made from it are durable and will never peel, swell, or warp. Fiberglass is moderately priced, dent resistant, energy efficient, and requires little maintenance. Fiberglass, however, can crack under severe impact.
Steel. The least expensive material used for French doors, steel also offers low maintenance. However, steel can dent and is difficult to repair; also, this material can scratch and will rust if not repainted regularly. Steel offers decent energy efficiency.
