Airtight garage door?
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.