Exterior doors

When it comes to wear and tear, few components of the home have more rigorous requirements than exterior doors. Beyond exposure to outside elements, exterior doors have to fit snugly into their jambs to seal out cold and heat, swing freely and quietly on their hinges, and lend a welcoming aesthetic to the home. Metal, wood, fiberglass and wood-composite doors each provide advantages in different areas. The cost of installing a new door in a residential structure depends on a number of factors, including size, type of material, raised or flush panels, veneer material, door core material, fire rating and finish.

Metal: Metal doors are the most popular exterior doors sold — a 1998 Professional Builder study showed that 42.1% of builders preferred metal entry doors, with 73.1% choosing them for other exterior doors. They can cost only half as much as wood doors, and because metal doors are filled with insulating foam or a wood-and-foam core, they have a greater R-value than wood doors. At the same time, metal doors dent and even rust if not properly sealed, and they might not last as long as wood doors. Inherently strong, metal doors come in different gauges to provide different levels of security.

Wood: The natural beauty of wood doors might be required by customers who want to preserve the original look — and material — of existing homes. However, doors made from young wood are prone to warping and twisting, especially when not sealed properly against heat and moisture. Wood doors have lower R-values than other types of doors; however, wood is an excellent insulator against temperature changes. While the air-infiltration rate of steel doors virtually doubles between 70 and 130 degrees, that of wood actually declines slightly, according to the Window and Door Manufacturers Association. In the PB study, 36.3% of builders reported preferring wood entry doors, while 17% liked wood for other exterior doors.

Fiberglass: Fiberglass or fiberglass-composite doors look and feel much like wood. A polyurethane core free of chlorofluocarbon provides excellent insulation. Because they are virtually impervious to extremes in temperature or even salt air, fiberglass doors are a good choice in tough environments such as beachfront homes. However, they are usually heavier and more expensive than metal. The Professional Builder study showed that 24.2% of respondents preferred fiberglass entry doors, and 12.5% preferred fiberglass for other exterior doors.

Wood composite: Wood-composite doors are made of medium-density fiberboard and particleboard, oriented strand board and plywood. (Finger-jointed pine is also used, although it is technically an engineered wood product, not a composite.) Composite doors look very much like natural wood, but they provide better insulation because of their foam cores.

Installation tips and costs

Although standard door size for residences is usually 6 feet, 8 inches high and either 2 feet, 8 inches or 3 feet wide, the trend has been moving to taller doors, sometimes 8 or 9 feet high. R.S. Means’ Residential & Light Commercial Standards suggests using a minimum of one hinge per 30 inches of door height on all wood and composite exterior doors, and using special heavyweight hinges for doors in excess of 175 pounds.

For a new installation, the carpenters simply lift the pre-hung door into the rough frame opening. After being squared, leveled and plumbed, the door is fastened to the wall through the casing and jamb. Allow a 1/8-inch clearance at the bottom of a wood door to accommodate its natural expansion in humid weather. Finishing tasks such as hardware installation, trim application and painting are left until the exterior walls have been finished on the interior and exterior faces.

Estimates for replacing an existing door must include costs beyond those included in the CostWorks table: removal and disposal of the existing door, removal and replacement of exterior siding if necessary, and weather protection and security if there is a time lapse between removal and replacement.

If the rough opening must be enlarged — perhaps because of adding a transom or sidelights — a new header must be installed, which in turn means more demolition and debris removal. If the rough opening must be shrunk, fill-in of the frame, sheathing and siding must occur. Repairs and patching to the interior finishes probably will be necessary, too.

Keep in mind the need to budget a little extra in case of damage during installation. The PB study showed that builders, on average, have to repair entry doors on 14% of their jobs. Fixing dents accounted for half of the repairs, with nearly a third caused by scratches and 22.5% devoted to finishing. The average cost of such repairs: $84.