· by Michael Blair, Nashville's Garage Door
Insulated doors are sold on energy savings, and Clopay’s insulation page says easier temperature regulation often leads to noticeable savings on monthly utility bills. Amarr, another door maker, is more candid: its guide to choosing a garage door calls a non-insulated door the better value if the noise and temperature swings don’t bother you. Which of those fits your house depends on what sits on the other side of the garage wall and above the garage ceiling.
When is an insulated garage door worth it?
An attached garage that shares walls with living space is where a better door has something to protect. Amarr’s page on energy efficiency points out that air in an attached garage can travel through the doorway into the living area, and Clopay suggests an R-value between 10 and 13 for attached garages. If there’s a bonus room over the garage, the door is only part of the answer. The Department of Energy’s Building America Solution Center says rigid foam added to a garage ceiling can improve the comfort of floors above an attached garage and tighten the air seal between garage and house.
A garage used as a workshop or gym is its own case, because you are heating or cooling the space you stand in. Clopay says a higher R-value helps keep a garage warm in winter and cool in summer, and that matters most in a garage someone actually spends hours in.
When is an insulated garage door not worth it?
When a detached garage is used only for parking, we tell the owner insulation is optional, since there is no living space on the other side of its walls for the door to protect.
An attached garage whose shared wall and ceiling are already insulated and air sealed is closer to that case. The Building America guide to air sealing the attached garage puts the effort into that shared boundary: a continuous rigid air barrier between garage and house, every seam, gap and hole in it sealed, and the rim joist of the shared wall sealed as well. Where that work has been done properly, we look at the door’s seals before we talk about a new door.
- Attached garage with rooms above: worth considering, along with the ceiling
- Detached parking garage: insulation is optional
- Workshop or gym use: worth considering
- Side weatherstripping and the bottom seal: check them on any door
- Garage ceiling under living space: insulate and air seal it
What R-value on a door means
R-value and U-factor measure different things. According to DASMA’s statement on garage door thermal ratings, R-value is a calculation that reflects only the insulation in one door section, while U-factor describes the whole door assembly, and with U-factor lower is better. Manufacturers in DASMA’s program test U-factor under the ANSI/DASMA 105 method at independent certified facilities. Amarr adds that the two ratings aren’t mathematically related, since the tests are completely different, so compare U-factor with U-factor and read a headline R-value as a number about the foam.
Clopay says polyurethane doors offer higher R-values than polystyrene doors, with polystyrene usually the cheaper of the two. Polyurethane is foamed into a dense, strong layer between the door’s skins, and Clopay credits the bonded layers of an insulated door with added durability and structural strength. If you’re pricing a replacement, our new garage door page covers the steel, carriage and glass doors we install.
The cheaper wins first
Weatherstripping around the perimeter and a good bottom seal are a small job next to a new door, and they close the gaps that let outside air straight in. DASMA’s thermal rating leaves air infiltration out entirely and treats it as a separate quality of a door, and Amarr’s garage door FAQs concede that the windows, sections and bottom seal of a garage door may not be completely leak-proof. Worn seals let air past an insulated door as readily as a plain one, and our post on bottom seals and the gaps they leave shows how to check and replace that strip.
Where there is living space over the garage, insulating and air sealing the garage ceiling is the step the Building America Solution Center recommends. Its guide to the floor above a garage calls for insulation that meets or exceeds the code level for your climate zone, in full contact with the underside of the subfloor. The door from the garage into the house counts too: the attached-garage guide calls for a self-closing, insulated, metal, fire-rated door with a good weather seal. If you’d like us to look at the seals and the door together, ask us for a free estimate.
Sources
- Clopay, Insulation — Temperature regulation and utility savings; R-10 to R-13 for attached garages; polyurethane higher R-value than polystyrene, polystyrene cheaper; dense, strong layer and added structural strength; dampens outside noise
- Amarr, How to Choose a Garage Door — A non-insulated door is the better value if noise and temperature swings are acceptable
- Amarr, Energy Efficiency — Air in an attached garage can travel into the living area; R-value and U-factor are not mathematically related; insulated doors generally quieter
- U.S. Department of Energy Building America Solution Center (PNNL), Insulating Existing Floors over Garage — Rigid foam on the garage ceiling improves comfort of floors above an attached garage and air sealing between garage and house
- U.S. Department of Energy Building America Solution Center (PNNL), Air Sealing the Attached Garage — Continuous rigid air barrier between garage and house; seal seams, gaps and holes and the shared rim joist; self-closing, insulated, metal, fire-rated door to the house
- Door & Access Systems Manufacturers Association (DASMA), Garage Door Thermal Performance Ratings That You Can Trust (2023) — R-value covers only the insulation of one section; U-factor covers the whole assembly and lower is better; ANSI/DASMA 105 testing at independent facilities; air infiltration rated separately
- Amarr, Garage Door FAQs — Windows, sections and the bottom seal may not be 100% leak-proof
- U.S. Department of Energy Building America Solution Center (PNNL), Floor Above Garage — Insulation meeting or exceeding code for the climate zone, in full contact with the underside of the subfloor
FAQ
Is an Insulated Garage Door Worth It Here — questions
Will an insulated garage door lower my energy bill?
It has the best chance when the garage is attached and shares walls or a ceiling with conditioned space, such as a bonus room above. Door makers say insulation can lead to noticeable savings, but we have not found an independent figure for how much. On a detached parking garage we treat insulation as optional, and where there are rooms above, insulating and air sealing the garage ceiling is the step the Department of Energy’s Building America guidance recommends.
What R-value should a garage door have?
Clopay suggests an R-value between 10 and 13 for attached garages or cold climates. R-value only describes the insulation in one section, though, so when comparing doors ask for the U-factor tested under ANSI/DASMA 105, which covers the whole door, and remember that a lower U-factor is better. For a garage used only for parking, insulation is largely optional.
Does an insulated door make the garage quieter?
The manufacturers say so. Amarr calls an insulated door generally quieter than a non-insulated one, and Clopay says insulation dampens outside noise such as lawn equipment and street traffic. If there is a bedroom over the garage, that is worth weighing alongside the thermal difference.
What do garage door insulation values mean?
R-value is a calculation of the insulation in one door section, while U-factor describes the whole door, and with U-factor a lower number is better. Manufacturers in DASMA’s program test U-factor under ANSI/DASMA 105 at independent labs. Amarr notes the two aren’t mathematically related, so compare U-factor with U-factor. Air leakage is rated separately.