I am currently planning on insulating my shed this summer to allow year round usage.
My first step is to insulate the whole shed.
– The walls and Ceiling are straight forward, I will be installing fiberglass batts, I'm just not sure which R-Value I should be using on either.
– I will then cover them with vapour barrier, and tape (Tuck Tape) all the seams and staple holes.
– The floor is another matter, I cannot access the underneath, nor do I know what the construction underneath is like. It is 3/4" plywood. Now do I cover it with vapour barrier, then 1" styrofoam panels, then 1/2 plywood, then I can finish it as I like. Or do I flip flop the vapor barrier and styrofoam.
Best Answer
For the R-Value of your walls and roof, it will depend on the depth of the framing, but assuming you're using 2x4 studs in your wall, then R18 is pretty standard. For your ceiling, again depending on your framing, R30 or R38 is typical for batts. Remember that you may be able to squeeze a higher R-Value batt in between the framing, but compressing the fiberglass effectively reduces the R-Value by creating thermal short circuits.
For the floor, install the rigid insulation, then the vapor barrier, then the floor boards. Here's a pdf which talks about vapor barriers: