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Thread: Garage door insulation value?

  1. #1

    Garage door insulation value?

    I'm building a new shop/garage and am picking the garage doors right now (it's really more like a shop with some garage doors). There will be two single-car doors.

    I'm looking at pre-insulated garage doors and am seeing R-values from 6.5 up to 18. Obviously "more is better" but is there a good way to calculate "how much better"? If I could find a way to compare heat loads that'd probably be best so I can see how much harder my A/C or heater will have to work. For reference I live in TN, so summers are 80's to 90's and very humid, and winters are around 30.

  2. #2
    Join Date
    Feb 2010
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    I’m assuming that the walls and ceiling will be insulated. I would get the highest R value that you are willing to pay for. R8 would be the lowest I would consider and R12 the highest I would pay for assuming the best is way more money. If your doors face west, the summer sun will be brutal. In the winter I only heat mine to a max of 64 but in the summer I like 72.

    If painting your concrete don’t paint within 12 inches of your safety sensors, all the way across the beam area. If you get a Chamberlain opener it won’t detect a leg or small item in the way. They refuse to admit the problem but also have no interest in seeing my proof that the problem exists. I filed a report with the CPSC.
    I think their belt drive with battery backup is the best opener out there but you just can’t paint the floor along that area.
    Last edited by Bruce King; 01-20-2021 at 6:02 PM.

  3. #3
    Join Date
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    Personally, if I were faced with putting "garage" doors on my future shop, I'd opt for doors that were as close to the same insulation value as my walls and also pay attention to how they seal. Your climate isn't much different from here. Part of your decision around this will also be which way the doors face so you can understand the impact of prevailing winds for winter and sun exposure for summer.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  4. #4
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    The bottom seal is easy to get right but the side seals should be installed with the door closed and pushed tight enough so the door does not rattle when the wind blows.

  5. #5
    Jim's right. It's very easy to get caught up in R values, but air leakage is the real killer. Unfortunately, I have yet to see a decent way to seal the sides of a garage door. The usual answer, those rubber strips isn't great, and in my case leak when I turn on the cyclone, probably because it's venting outside.

  6. #6
    Quote Originally Posted by Andrew More View Post
    Jim's right. It's very easy to get caught up in R values, but air leakage is the real killer. Unfortunately, I have yet to see a decent way to seal the sides of a garage door. The usual answer, those rubber strips isn't great, and in my case leak when I turn on the cyclone, probably because it's venting outside.
    If you didn't get leakage from somewhere when you fired up your cyclone, you would not have anything venting outside

    Same with heaters, wood stoves, etc. The make up air has to come from someplace.

  7. #7
    Join Date
    May 2013
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    Smyrna Mills, Maine
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    I put a garage door in my new shop this summer. I purchased the R-18 and the double seal rubber strips for the outside. My shop is heated all the time at 50 and usually 60 when I'm working. There are no drafts around the door at all, I'm happy with it.

  8. #8
    Join Date
    Jul 2016
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    My house in Dallas the metal garage doors faced due south. The doors had no insulation.

    On a normal 90+ degree day, I could take a reading of 140F off the inside of the door.

    When I insulated the doors, with self mount kit insulation from Home Depot, that reading came down to about 5 degrees above the air temperature inside the garage.

    With a mini split, I later installed in my garage, with AC in the summer and heat in the winter. Without the insulation, that mini spit would never have been able to cool/heat the garage space, especially in the summer with the radiant heat coming off the doors.

    The direction the doors face has a huge effect on the heat they will radiate in the summer.

  9. #9
    Join Date
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    I think that Jim B. hit the nail on the head. I'd insulate the garage door as close to the value of the wall insulation as I could. A garage door, or any window or door, is essentially a big hole in a wall that lets warm(or cool) air escape almost unimpeded without some kind of insulation. The closer that you can come to matching your wall R-value, the more stable the interior environment will be. In the long run, insulation is far cheaper than fuel or electricity.

  10. #10
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    While many of us have our shops as "conditioned space", even folks who work at ambient temps for the season will benefit from insulation. Chris makes a really important point above about his garage door experience when it was south facing in a warm climate...that was quite a temp rise projecting through an uninsulated door! Folks who have outbuildings that have no insulation are at the mercy of the sun in warm times of the year and even a little insulation can greatly reduce the "oven effect" in the space, even when there is great cross ventilation. So yes...treat the doors with the same care as other walls as best as possible.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #11
    Thanks for the advice everyone. There will be two doors, one north facing and one south, but the south facing one doesn't get sunlight due to a boatload of trees. I'll look into the sealing types. The math says a higher R value won't save lots of money (ignoring radiant heating, of course) but the sealing and general "draftyness" worries me. If it's any help, the builder wants to use Clopay garage doors. I am only just now starting down this path so I'll look into how they seal at the sides. I've never used these before.

  12. #12
    Join Date
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    To provide a contrasting point of view...

    I have a single low-end (but insulated) Clopay garage door on one side of my shop. I can't remember, but definitely not high R value (about 1 inch of foam in each panel) and the vinyl seals around the perimeter block wind gusts decently. The rest of my shop is pretty nicely insulated, but not perfect by any means - it's a 120 year old barn after all. I do condition my space with a mini-split year round and it is very comfortable in all seasons - I keep a base temp at all times to eliminate humidity concerns and then touch up the thermostat while working. Works wonderfully.

    My point is...

    While I would definitely rather have better insulation and sealing on the garage door, we have found that the hit on the electric bill is very minor when comparing extreme-temp months (those where my mini-split is being asked to keep more than 10 degrees delta vs. outside air) to the mild-temp months.... As in, the swing between our most expensive month and cheapest month is hard to even detect in our bill. So upgrading just hasn't been a priority because it's not impacting my enjoyment of the space nor is it impacting our wallet in a meaningful way.

    Of course, method of heating/cooling is playing in my favor here as a good mini-split is very efficient.

    That said, if money had been no object when I installed the door many years ago I would have put in the best door I could get. But money WAS a major consideration back then, and the performance has been fine.
    - Bob R.
    Collegeville PA (30 minutes west of Philly)

  13. #13
    Thanks Bob. I tried running this through a calculator and it estimated something like a $5 a year difference between R6 and R12, which makes sense with your math. Even at R16 I think the difference was still under $10 a year. Thanks for the info on the Clopay door. I'll probably try to get the one with the best seals rather than the best direct R value since I don't think it'll get any direct sun.

  14. #14
    Join Date
    Jan 2019
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    Fairbanks AK
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    Another way to look at it is to compare, relatively, the insulation of the shop door to the insulation in the walls of your shop and then look at the insulation in walls and windows of your home.

    We could probably all save a few bucks if we splurged on a $80k set of windows for the house, but not enough savings to cover the payments on the windows.

    I agree with all of the above air seals are very very important. All other things being equal, I would rather have moderate R value and minimal well controlled air leaks than crazy R value and moderate air leaks.

    If your overhead door is in line with the other insulation on the property it won't hurt your resale value. If you splurge on the most insulating garage door money can buy it probably won't help the resale value.

  15. #15
    Join Date
    Mar 2003
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    Central PA
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    I'll add another option. My garage (shop) was built with one standard 9' wide opening. Instead of using an overhead door I build two hinged doors that are 6" thick. They are effectively moving walls hanging on heavy hinges. They have studs in them so I can hang things on them. I also don't have overhead tracks to contend with but I do have to leave room for the doors to swing in.

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