Insulating a Heated Workshop
I am confused and need advice. I am building a large workshop … just over 3000 sq ft on the bottom floor and just over 1000 sq ft of attic storage. It has 16 ft walls. I have divided it into three bays. There are two 14 x 14 doors in two of the bays.
I live in Vermont .. we can hit -30 … only average 5 days above 90
Standard stick construction … 2 x 6’s with lots and lots of blocking … covered with 1/2″ OSB.
We used a thicken edge pad (hmmmm … long story how I was talked into this, but it is what it is) … 2″ of foam under it … 2″ around the outside edge …. plus 2″ starting at the bottom of the edge and going out 2′
So, I am planning to heat it. I have natural gas already to the building. I will use three zones (or three furnaces or three ???). Since I do not use it every day, I want to keep it as say 45 or 50 deg … just so the coolant in my machines, my paint …. anything in the shop will not freeze.
On the days I go out to the shop, I will heat the bay I am working it.
So, I have been careful to try stopping air leaks … used a gasket and caulk under the sill.
I had planned on just doing a standard insulation job … batts between the studs … blown in insulation in the ceiling (I have a 24″ energy heel so with 18″ of insulation I will have a 6″ air gap … great since I am planning on a metal roof over purlins.
As I was looking at the building I realized just how much bridging I will have because of the blocking, lvl’s and such.
I have a tight budget … building it all myself … so I can’t get extravagant and use something like spray foam or build a double wall.
I thought maybe I could buck out the windows 1 1/2″ (2 x 4 on flat) … put 1 1/2″ of iso or xps reclaimed foam on it … plus the batts … strap the foam, cover with vinyl siding … all set.
Then a friend who is very eco building smart said NO! First he said I should not heat the building … ok, not an option.
Then he said either use 6″ of foam (out of my budget) or use none. He said I would rot my walls away … the water would condense on my wall sheathing.
I even saw one person put the insulation on the inside …. but might have the same problem?
I tried reading up on this … it looks like it might be true but then there is always talk about water load (should not be much in the shop) and use of a vapor barrier inside.
Just not sure where to go from here.
Here is a link to some videos my wife put up showing the project.
Thanks …. Mike
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