Choosing a door that will keep out the cold
Doors have a tough job in Alaska, where inside and outside temperatures can range more than 100 degrees in the winter, causing sticking, jamming, warping and other cold climate phenomena.
Exterior doors used to be custom made by hand or in local millwork shops. Door-hanging was an expert skill for craftsmen, who built the jambs, mortised the hinges, and hung doors complete with latching hardware and locks. Most doors were wood, designed with many different panel styles and elaborate trim, with brass interlocking seals to keep the elements out.
It’s a little different today. Most doors come “pre-hung” in their own frames. Doors are mass-produced in standardized sizes, typically clad in metal and made with vinyl seals. The value of a door is measured primarily in terms of style, price, and performance.
Because they come as a self-contained unit, newer doors often fit and insulate better than older doors. All-wood doors may have the most impressive appearance, but they provide the least insulation and require regular upkeep. All doors will contract and expand with the temperature, but wood doors are the most dynamic and can also react to humidity, which can make them difficult to open and close at times. For the most part, people prefer wood doors for reasons of aesthetics, not function.
The most common doors today are metal or fiberglass. The better insulting doors are made with polyurethane foam insulation cores encased in metal. This method can provide insulation values up to R-6 – several times the insulating value of a solid wood door. Heavier-gauge steel will provide more resistance to denting or other damage. Rust-free aluminum cladding is often used, but can easily be dinged. Fiberglass doors can simulate the appearance of wood and they won’t warp, dent, rust or crack; yet they are typically more expensive than steel doors. Vinyl doors are low-maintenance and weatherproof, but not as sturdy as fiberglass or steel.
Some quality doors come with magnetic stripping like the kind you find on your refrigerator to provide a tight seal with the doorframe. Interlocking seals, especially in the threshold, are effective at keeping the elements out. Vinyl or rubber seals tend to crack and fail in Alaska’s extreme cold temperatures. When installing a pre-hung door, expanding insulating foam is typically used to fill any gaps between the door frame and the rough opening. Generally speaking, the quality of a pre-hung door will be determined by the quality of the wood framing and hardware, and how well the door fits inside the frame.
Windows in doors are a source of significant heat loss. If you choose a door with a window, look for at least double-pane construction and warranties that cover the window seals and any hardware used to open or close the windows. Fixed windows that do not open will seal better than windows with sliding panes. Sliding glass doors, which are popular on decks for the views they provide, are major sources of heat loss. Good seals, hardware, and warranties that guarantee proper operation of these doors are critical. If you buy a sliding door, try to find one that allows you to replace the weather stripping when it wears out. In general, doors that swing open will seal better and be easier to maintain than sliding doors.
Whatever type you choose, multiple panes and “low-e” coatings that reduce heat loss are important. Look for glass doors that employ a thermal break – a non-conducting central frame member – to prevent heat loss from the inside portion of the frame to the outside.
Finally, installing storm doors over your existing exterior doors can be a cost-effective way to increase the energy efficiency of your home, especially if you’re adding to an older, under-insulated door. Storm doors offer the same material and insulating choices that regular doors do, but can be fitted with screens for the summer months. Be mindful of direct sunlight in the summer–heat can build up between the two doors and possibly warp the exterior door.