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Community and Q&A

Airtight garage door?

kevin_in_denver | Posted in Green Building Techniques on

I have a unique set of requirements for a garage I’m building. I’ve been unable to find anything online in terms of 7′ x 7′ air tight garage door.

1. Because of plumbing in the garage, I have to heat it all winter in an especially high altitude (cold) location in zone 7b.

2. The insulation is R-40 walls, R60 attic, R-20 around the foundation, with FPSF detailing.

3. I don’t need to open the garage door more than about 10 times per year.

4. I didn’t insulate under the slab, in the hopes I could get free geothermal heat radiating up at the year round average soil temperature of 43 deg. F.

5. Since it’s not for vehicles, I want the garage to be very air tight.

I ruled out an overhead garage door, because I felt it would be impossible to air seal.

I’m just about to start making a pair of slab carriage doors with piano hinges and face seals around all four sides, but I don’t want to invent the wheel.

Has anyone ever done this? Is there a commercially available solution of some sort?

I’m OK with outswinging carriage doors even though they will be a major problem with snow in the winter. Inswing doors that size aren’t viable, because you can’t close the door after bringing in something large. I’d like to keep the cost below $2000.

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  1. GBA Editor
    Martin Holladay | | #1

    I think you will have to build your own doors. It's going to be a challenge to maintain contact between these large doors and your weatherstripping on all four sides of the door, since the doors will expand and contract with changes in humidity and temperature.

    You'll have to spend some time thinking about your threshold details. If you don't need to drive vehicles through the door, you can install a wood threshold.

    I don't understand why you didn't install sub-slab insulation. The fact that the soil temperature is 43 degrees F won't help you in any way with your heating bill, unless you plan to set your indoor thermostat for 42 degrees or less.

  2. kevin_in_denver | | #2

    Right, the goal is to maintain, say, 35 degrees or higher to prevent the pipes from freezing.

    According to PAHS principles, having a perimeter insulated slab with an insulated shell above it may cause the average soil temperature beneath it to slowly rise:

    This effect should give me a larger margin of safety after a couple of years.

    I did install a treated 2x6 threshold, supported from below with a combination of concrete block and XPS. The edge of the 2x6 will provide the surface for a face seal.

  3. gusfhb | | #3

    42 inch doors aren't all that big. I built 12 foot wide swinging set many years ago that worked ok until I left them open and the wind got them. The biggest leak risk area would be where the two doors meet. For a low use door you could latch it to a removable center stop, allowing you to load the seal where it would otherwise be 42 inches away from support.

    I have been pondering a more airtight overhead door for a garage I am planning and have come to think that the general concept should be able to be airtight with a little work but what is not up to snuff is the rail system. Perhaps a more accurately constructed wheel assembly would allow for real weatherstripping.

  4. user-757117 | | #4

    How are you planning to latch the doors shut?
    You may want to include a provision for either pins/deadbolts at the top and bottom where the doors meet or a crossbar across the inside (to keep the doors from moving in the wind).

  5. kevin_in_denver | | #5


    Check. I built a beefy wood jamb & threshold. I think I'll do an astragal rather than a removable crossbar. Maybe a 1x4? Between the doors, in addition to a face seal, I'll have an edge seal that requires both doors to be shut at once. The 3" piano hinges should be able to take it.


    The conventional overhead door design is very robust and highly tolerant of any misalignment. But that feature precludes the ability to have much sealing force. What you suggest can be done, but everything in the entire assembly needs tighter tolerances.

  6. kevin_in_denver | | #6

    OK, here's how I made the door panels:

  7. gusfhb | | #7

    link was goofy, wants me to sign in

    R3? I thought you wanted insulated,,,,,,,,[runs quickly away]

  8. kevin_in_denver | | #8
  9. kevin_in_denver | | #9

    I finished and installed the door just before the first freeze of the season.
    Wound up with a similar door to the video above, except that I emphasized building it like a SIP is built.
    Here are some photos-

  10. Jon_R | | #10

    I'm pretty sure you could find ways to protect pipes from freezing without heating an entire garage. If not, a steel or plywood SIP hinged door makes sense to me.

  11. Anon3 | | #11

    Air tight garage is more prone to carbon monoxide...

  12. Cpete777 | | #12

    There is a product called thermotraks that is very simple and effective for making a garage door air tight and still operational. Only product out there to achieve this that I have seen.

    1. user-5946022 | | #13

      Does anyone other than cpete777 have any independent info about this product?

      Seems like a decent idea, but cpete777's only posts to GBA have been about this product, and the company is owned by a guy named Carl Peterson. Could be useful for a company to let us know about a helpful product they make that we may not know about, however the poster did not identify himself as associated with the company (but did not really try to hide his identity either....)

      1. etekberg | | #14

        LOL; good detective work!

  13. walta100 | | #15

    This web site seems to have the doors you are looking for but I am guessing they are proud of their products.

    “The Most Insulated Airtight Lightweight Strongest Door”
    This claim seems over top to my ear but they put it in writing.


    1. Expert Member
      MALCOLM TAYLOR | | #16

      I love sites that tell you to "contact your designer for more information".

      Like I'm sitting in my office with a bat-phone connected directly to them in a way a customer isn't.

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