How to Insulate a Cement Root Cellar

Insulate the walls separating your concrete root cellar from the rest of the basement. Install insulation on the side of the wall that faces the basement, not on the interior of the root cellar. This will keep the warm air from the furnace, hot water heater and laundry from seeping through the walls and entering the root cellar. Glue rigid foam insulation panels to the wall with construction adhesive. Butt the edges of the insulation against each other. Cut insulation panels with a razor utility knife, as needed, to completely cover the concrete walls separating the root cellar from the rest of the basement.

Install insulation on the ceiling of the root cellar. This will help prevent air infiltration from the living quarters upstairs. Rigid foam insulation is the best choice, as it will not allow mold growth, which can occur with fiberglass insulation. Apply construction adhesive to the back of the rigid insulation panels and insert the panels between the joists in the ceiling of the root cellar. Use foam caulk to fill in any cracks or spaces that cannot be covered with insulation.

Apply insulation to one side of the door of the root cellar, preferably the side facing the basement rather than inside the root cellar. Remove the door and its hardware. Measure and cut out spaces in the insulation for the doorknob and the hinges before gluing the panels onto the door. If necessary, add a strip to the bottom of the door to keep cold air from seeping under the door into the rest of the basement.

Create a sandwich made of two pieces of plywood encasing a piece of rigid foam insulation to replace the glass in the root cellar's window. Drill two holes in the sandwiched board using a drill fitted with a hole saw, to accommodate vent pipes. The vent pipes, when properly installed, remove warm air from the root cellar and draw in cool air, as long as the air temperature outdoors is cooler than the temperature of the root cellar. Install one pipe so its open end is about 12 inches below the ceiling of the root cellar. Install the other pipe using a 90-degree fitting and an extension, to bring the pipe down to about 12 inches above the floor. Cool air is drawn in through the pipe near the floor, while the pipe near the ceiling draws warm air out. Install shutoff valves on the ends of the pipes and close them off when freezing temperatures set in. In areas with extended periods of below-freezing temperatures, keep the valves closed until the temperature rises above 32 degrees F. Keep the valves closed when outside temperatures are above 45 degrees. This will help keep the root cellar in the ideal temperature range for storing produce.