There are two strategies to dealing with a cold storage.
Either you close it off from the rest of your finished basement with a steel insulated door, or you embrace it as an area of great potential.
Now, you may question the great potential designation given to a room that was – up to this point – the go-to storage area for beets and potatoes. I understand the skepticism.
However, if you own a fridge and don’t have to hitch up the team of horses and wagon in preparation for your weekly ride into Dodge for supplies, then it’s probably safe to decommission this former storage site.
Where’s the potential? Well, the room most likely has four concrete walls and a concrete ceiling, creating the perfect soundproof environment for an office. Or, if space will permit, this could be a terrific theater, or fitness area.
Now, how do we make this room livable?
First, we’ve got to solve the outdoor issue. Cold storage areas are usually located under a poured concrete slab, which serves as a porch or landing, leading to the main entrance. To prevent moisture from seeping into our future living space, the porch surface will need to be sealed, or better yet, covered with a roof extended over it. Then, before we insulate, you’ll need to call your heating and cooling contractor, an electrician – and a plumber, if the room is to be served by a sink, shower, or some type of water supply.
The room will minimally need a little lighting and a few plug outlets. If the room is large enough, it will most likely need its own warm/cool air supply and cold-air return.
So, with this impending ductwork and electrical wiring to come, you’ll need a mechanical plan so that the ceiling joist can be framed in a manner that will least effect the floor-to-ceiling height. With a mechanical plan completed, we can insulate the exterior walls and ceiling.
It was common practice to put a couple of round, four-inch vents in the cold-storage wall. Because the air temperature and quality in this former cold storage area will now be serviced by your furnace, you won’t be needing this outside air source anymore. So, block them up with a pre-mixed sand/concrete product.
Next, and like any other concrete basement wall, we install a Johns Manville polyiso, ridged foam board, directly onto the concrete. With the reflective side of the foam board facing the interior, the Johns Manville polyiso can be fastened to the concrete with PL premium glue. Choose at least the one-inch thick foam sheathing, which offers R-6 of thermal value. A 1.5-inch thick foam sheathing is better, with a two-inch polyiso, offering R-12 of thermal resistance, being the best option. Seal the concrete ceiling of the cold storage with this same polyiso product.
Normally you wouldn’t need to insulate the ceiling area of a basement, because usually there’s a heated home over top. In the case of a cold storage, all you’ve got overtop is about eight inches of concrete. As a result, this cold storage ceiling is basically an extension of the foundation wall, and should be treated as such.
With the polyiso sheathing glued to the walls and ceiling – Tapcon screws with washers will help with the gravity issue – frame a 2×4 stud wall directly over the foam board. The existing cold storage height will determine whether 2×4 framing will be possible on the ceiling.
Added insulation, light fixtures, and ductwork, will all be easier to install if the ceiling can accommodate 2×4 or 2×6 framing. Otherwise, the ceiling will need at least to be strapped with 1×3 spruce.
Once the wiring is complete, fill the 2×4 cavity of both wall and ceiling with R-14 fiberglass pink insulation. Next, install a six-mm clear plastic over the insulation, then cover the wall and ceiling with a 0.5-inch, mold tough type drywall.
Enjoy your new found space.