I built a walk in flower cooler. I used fiberglass batts. Not the idea material but i had it and it only needs to last a couple years at most.

Since I built it I found out we may be moving the shop within a year. The cooler will then be used only for a few day near holidays.


The wall against the outside brick wall has a vapor barrier over the bricks. I then built a 2x4 wall with enough room to put an R-24 batt behind the studs. I then put  R15 in between the studs. On the face of the studs the inside cooler wall I put 1/2 rigid foam with aluminum face on both sides. It's rated at R4. So I have about R40 or so in the side, front and back walls.

The ceiling  3 layers of the R24 plus 3 inches of rigid foam on top of 12 inches or so fiberglass under that. The foam up was there when we moved in. So its at least R100  I put the 3 layers of R24 up there because I had it left over and it was in the way.

Now the last wall that was all ready built. 1/2 inch dry wall on the outside of 2x4,s  with R15 with plastic plus some roll foam stapled to the insdie. I added the aluminum coated rigid foam to the inside. all joints are covered with metallic tape so its pretty air tight. However it only R20 or so at best.

Now I dont have the room to build even a 2x2 wall with R24 batts behind it. it would restrict the walk way to the back door too much.

I do have 6 inches of room. I have a bunch of 2'x2' Styrofoam squares 2 inches thick. I have enough for 3 layers to make up that 6 inches. If I glued that to the drywall in 3 layers overlaping seems and taping it what kind of R factor would I have in that wall. Would it e close to the R40 i have in the others ?

just set it and forget it.