Air / Argon Insulating Heat Transfer Glass Panels Energy Efficiency Insulating Value

Going Online
Whether you buy at a store or online, you'll save time by doing some research online and at least visiting a store to truly see what you're buying. Manufacturer sites describe materials and offer catalogs, and can help you to find a local retailer. And even if you don't see the exact door you want, a similar model can give you a good idea of construction and finish.
Energy Efficiency
Steel and fiberglass doors typically have more insulating value than wood doors. Models that are Energy Star-qualified must be independently tested and certified, and often boast tighter-fitting frames, energy-efficient cores, and, for models with glass, double- or triple-panel insulating glass to reduce heat transfer. You'll find more details on the federal EPA's EnergyStar website. But you may not save as much as you think, since doors are a small part of the surface area of a house and typically don't allow significant amounts of warm air to escape. What's more, heat is generally lost through air leaks around the door, not through the door itself.
Installation
Entry doors are also known as door systems because they come pre-hung in a frame and are often pre-drilled for a knob and deadbolt. Unless a replacement door is part of a larger remodeling project, you may want the new door to be the same size as the old one. Choosing a larger door or adding sidelights means redoing the door framing around the door—a job best left to a contractor. Home centers generally offer installation or referral services. Unless you're a skilled carpenter, you may also want to hire a pro to install same-size doors.
Keep Yourself and Your Family Safe
It takes a quality door lock to deter burglaries and home invasions. Many crooks kick in doors to get in. But unless your door is hollow, it's not the door itself that lets burglars in. Our tests with a battering ram have shown little difference in strength among door materials. All eventually failed because the doorjamb split near the lock's strike plate, though we also found that beefed-up locks and strike plates can greatly increase a door's kick-in resistance.
Some other ways to strengthen an exterior door: Use a lock with a 1-inch-long deadbolt and a reinforced metal box strike. Use 3-inch-long mounting screws so they lodge in the framing beyond the door jamb. And don't overlook the door that leads into your house from the garage.

Major door manufacturers such as Masonite, Peachtree, and Pella offer a wide range of doors made of various materials. Here are the types of door materials to consider.
Fiberglass
A practical choice for most people. These doors are available with a smooth surface or, more typically, an embossed wood-grain texture. An edge treatment on some makes them look more like real wood.
Pros: Fiberglass doors resist wear and tear better than steel. They can be painted or stained, are moderately priced and dent-resistant, and require little maintenance.
Cons: They can crack under severe impact.
Steel
This type of door accounts for about half the market.
Pros: They're relatively inexpensive and can offer the security and weather resistance of much pricier fiberglass and wood doors. Steel doors require little maintenance—unless dents are a part of your home scenario. They're energy-efficient, though adding glass panels cuts their insulating value.
Cons: Steel doors didn't resist weather as well as fiberglass and wood doors in our abuse tests and the laboratory equivalent of torrential rain, strong winds, and a decade of wear and tear. And while they're typically low-maintenance, dents are hard to fix, and scratches may rust if they aren't painted promptly.
Wood
Provides the high-end look that other materials try to mimic.
Pros: Solid-wood doors were best at resisting wear and tear in our tests. They're also the least likely to dent, and scratches are easy to repair.
Cons: Wood doors remain relatively expensive. And they require regular painting or varnishing to look their best.

Manufacturers offer dozens of options for panel and glass designs, grille patterns, sidelights, and transoms. The more elaborate the design, the more the door will cost. Here are the door features to consider when shopping.
Adjustable Threshold
This helps keep any door weather-tight over time. Otherwise, you may eventually need to add a new sweep to the bottom to seal out rain and drafts.
Glass
Glass inserts are attractive, but they add to the cost. If you're buying a door with glass near the doorknob or with glass sidelights, consider a double-cylinder dead-bolt lock. You need a key to open this type of lock whether you're inside or outside, so a burglar can't simply break the glass and reach in to open the door. Some municipalities ban double-cylinder locks since they may make it harder to get out in an emergency; check with your building department, and always leave a key within arm's reach of the interior lock. Glass inserts also cut the door's insulating value, though double- or triple-panel glass reduces that effect.
Rails and Stiles
These are the horizontal and vertical parts that brace a wood door. Solid-wood rails and stiles may eventually bow or warp. Look for rails and stiles made of laminated wood covered with veneer, which provides the greatest resistance to warping.