Q: I do projects in my garage, which has a bedroom above it. The garage door is an old metal one with no insulation, so I think I should replace it. What type is best?
A: It sounds like you definitely need to make efficiency improvements to the door-—for comfort while working, and to halt energy loss through the floor above. If the builder installed an inexpensive, inefficient door, as many do, or it’s an older building, it’s likely the floor above isn’t well-insulated, either.
When evaluating energy efficiency projects, keep in mind: Hot air goes up, but heat energy moves in all directions, including down. If your garage doesn’t have a furnace duct, but stays reasonably warm, it’s probably drawing heat from an adjacent house wall and the floor above.
Before you buy a new door, however, inspect the existing one. If it’s in fairly good shape, with no significant drafts between the panel joints, consider installing a garage door insulation kit. Some kits provide an insulation value as high as R-8, but they won’t seal air leaks through the joints. Owens Corning® makes an easy-to-install kit that includes vinyl-backed fiberglass insulation batts, retaining clips and tape. Cut the batts to fit the door panels, and apply strips of double-sided tape on two spots on each panel. Stick the retaining clips on the tape and push the insulation over them. A top clip snaps over each clip to hold the insulation securely in place.
Other kit advantages are reduced outdoor noise and lower lighting costs (the exposed white vinyl backing reflects light so you need fewer lights on).
If you decide on a new door, the most common materials are wood, aluminum/glass, and insulated steel or fiberglass. The last two offer the best efficiency, because of the insulation value and rigidity of the door to remain airtight over its life.
Many insulated steel doors are “wind rated” for severe weather. Even if your area doesn’t have frequent high winds, install the galvanized steel supports across the door’s inner surface if they are included with it. As the door rolls to open, the edges are not interlocked to support each other. Without the steel supports, the panels may flex and crack over time.
If you prefer the look of wood but want higher efficiency, select a clad-insulated steel door. Clopay® doors have a one-half-inch-thick polymer coating on the exterior steel skin with a wood grain molded into the surface that looks identical to stained wood. Another option is an embossed, simulated wood finish that’s painted on.
A very popular style is a simulated swing-open carriage door. It still rolls up like a typical panel garage door, but from the street it appears that two doors would swing open. These attractive doors often have decorative glass across the top panel that adds natural light to the inside.
An insulated steel door is probably the least expensive design to meet your efficiency and comfort needs. Some are foam-insulated, such as the Clopay Gallery Collection double-wide, with insulation values as high as R-19. The foam inside the door can be either glued-in rigid polystyrene or blown-in urethane foam. Urethane has a higher insulation level, but either should be satisfactory.
When choosing a steel door, look for a thermal break separating the outdoor and indoor metal skins to reduce heat loss. This is not a factor on a fiberglass door. If you have kids, look for pinch-resistant panels that are designed to push a finger out of the panel joints as the door closes. If you want glass in the door, make sure it’s at least double-pane insulated glass or low-E for better efficiency.
James Dulley is a nationally recognized mechanical engineer writing about home energy issues for the National Rural Electric Cooperaive Association. If you have a question for Jim, please email firstname.lastname@example.org, or mail to James Dulley, Michigan Country Lines, 2859 W. Jolly Rd., Okemos, MI 48864. Be sure to let us know which electric co-op you receive service from. Visit dulley.com for more home improvement and do-it-yourself tips.