Doors are important features of every house’s architecture as they create an image that is the first close-up impression of what is to follow inside. Typically not even on the list of important features, is the door’s energy efficiency.
A door’s impact on energy is more from its fit than its R-value. This is because doors are relatively small in area, but have a LOT of lineal footage of ‘crack’ (potential draft) with seals that tend to wear out with age and abuse.
If doors include windows or window panels next to the door, the glass must be safety rated against breakage per code. Often plastic is used instead of glass. This tends to make window panels much more expensive than conventional windows of the same size.
Insulated steel doors have an R-value of about R-5. Solid core wood doors are about R-2. There are many types of weatherstripping and door sweeps (thresholds) available; the best for steel doors are magnetic and for wood doors are spring metal ‘V’ strips.
Be sure to keep weatherstripping in good condition; replace as needed to keep a tight fit.
Storm doors are generally not needed, and should not be used with insulated steel doors that have decorative plastic molding. This is because during the summer excess heat build-up between the doors will cause the plastic to melt, sag, warp, etc., and can peel paint.
The best garage doors are the insulated steel type, with inter-locking panels and high quality weatherstripping. Even if the garage is not heated, a good door will be an important barrier for keeping the garage warmer and making it a better buffer to the house.
Source: Text Bob Fegan 12/2008; IR Image by Bob Fegan;