Door types: Knowing the type of door or doors that need repairing helps your service professional bring the right tools for the job. Every door type has different characteristics. For instance, exterior doors are heavier and generally have more hardware. Sliding doors can present track repair problems.

Basic problems: If a door is painted or stained, there's a chance that the repair may remove some of the original paint or stain. Having matching paint or stain on hand could save money and hassle.

If you must replace your door's windows or the door itself, here are some tips to keep in mind. Keeping with today's concerns for saving energy, windows may be standard single glazed, dual glazed or even triple glazed. "R-values" measure heat loss through glass: the higher the R-value, the higher the glazing's resistance to energy loss. By increasing a window's R value from 2 to 4, you can cut energy loss by 50 percent.

Efficient solutions: Here are some energy-efficient options: Low-E glass has a virtually invisible metallic coating that reflects heat and protects carpets and furnishings from fading by reducing damaging ultraviolet rays from the sun. Even more efficient insulating windows have Argon gas, a natural, colorless, non-toxic gas that is sealed between glass panes. Insulating Low-E glass filled with Argon gas has about twice the insulating qualities of standard dual glazing.

Solar bronze and solar gray tinted glass help keep out unwanted heat and ultraviolet rays. If there is a possibility of ultraviolet (UV) damage to floors, rugs and furniture, consider choosing a glazing that resists UV rays.

Most doors are designed to look like wood. Materials such as steel and fiberglass can simulate the look of wood, plus they are more affordable, have a greater insulation value, and require far less maintenance.

All-wood doors are made from softwoods or hardwoods, which are more durable and elegant. Fiberglass-composite doors, made from a core of rigid insulation clad with a fiber-reinforced polymer, are often embossed with artificial wood grain so they look like wood. Steel doors, made of heavy-gauge, galvanized steel over a core of rigid foam, are strong but look less like wood. Their surfaces usually are coated with polymer or vinyl and are wood-grain embossed. You can also buy doors that consist of veneer applied over solid wood, or veneer applied over a hollow core.

A door will occasionally sag under its own weight and bind in the doorframe. If the situation isn't corrected, it will get worse over time until it's virtually impossible to open or close the door. Planing or sanding the upper door edge is only a temporary fix because the door will continue to sag. Instead, remove the screws from the upper hinge leaf that's attached to the doorjamb and replace them with three-inch decking screws. The screws will pass through the jamb and reach deep into the trimmer studs of the rough opening. Tighten the screws just enough to pull back the door a little bit. Be careful not to overtighten them or you'll bow the jamb and distort the swing of the door.

-- Tips courtesy of HomeAdvisor.com