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Manitoba, Canada | I’m going to be building a shop soon. I’m going with 8” fibreglass in the wall cavity and on the inside I’m putting full sheets of 2”styrofoam with taped seams and an additional vapour barrier. Inside of that there will be strapping and then 3/4” plywood for 8 feet and then metal for the rest of the wall and ceiling. I know that spray foam is the “best” and I really wanted to go that route. In the end though there were two strikes against it. It moves the vapour barrier to the outside of the wall and that is not the best in a cold climate and it still left a partial thermal bridge. I guess strike 3 is it is also the most expensive.
In the end, even a reasonable job of insulating is likely going to be more efficient per square foot than any doors you install. After all that time spent designing it to be as efficient as possible, I am breaking this envelope with a big 40 x 20 bifold and a 20 x 18 overhead door. In both cases the best insulation available is 3” of foam for only approximately R26 as well as numerous possible air entry points.
I have a 28 x 34 shop now and after researching and being a bit disappointed that R26 was the best door I could get I went and looked at the door on my existing shop. It’s a 12 x 14 overhead and is only 1 3/4” thick. I am heating that shop with a 5000 watt electric heater. That’s only roughly 17000 BTU. It cycles off and on even in this -35 c weather. Maybe R26 won’t be so bad after all.
Edited by havin'funfarming 2/11/2019 05:53
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Shop wall insulation: spray foam vs fiberglass
