A couple of years ago I built a dry root cellar in our basement in order to keep vegetables and fruits over the winter. I framed in a corner of our basement, put in a door and used a window to give the room access to the cool air from outside. Last year I acquired a half dozen refrigerators in order to store spawn and fresh mushrooms. I decided a walk-in cooler would be more efficient and convenient, so I decided to make our root cellar also work as a walk-in cooler.
The walk-in cooler is essentially complete now, after working on it on-and-off for a couple of months. This just in time for my first order of spawn that came in yesterday – about 100 lbs. of shiitake sawdust spawn.
I started the work in December by papering (can that word be used here?) the walls of the root cellar with rigid insulation, enough to give the room an R-value of at least 20. I didn’t screw the insulation into the walls behind. Rather I just cut the pieces tight enough so that they would stay put.
This photo was taken just outside the root cellar/walk-in cooler. While I used pink insulation for the bulk of the insulating value, I finished it off with the yellow insulation with a foil face, since this surface will shed the condensation that occurs in this type of environment. I also taped all the seams with foil tape and spray-foamed around the receptacles. Unfortunately the yellow insulation in particular is not an environmentally friendly product, but I couldn’t think of a good alternative. Please comment if you have any thoughts about this.
I put insulation on the floor and I used self-tapping screws with a rubber gasket to attach the insulation to the ceiling. Here is a photo of the wood threshold I put in that shows how much I built up the floor. After putting in the threshold I put down some painted plywood sheets in order to protect the floor insulation.
Finally, I insulated around the window and hooked up the coolbot, a device that tricks the a/c unit into staying on to cool below the temps it would usually go. My thermostat is currently set at 38 degrees, or about what a refrigerator runs at. So far it is staying at that temp, or a bit cooler.