Apply the insulation to the cold cellar or garage wall separating the heated basement from the unheated space, as if it were an external wall. Weatherstrip and insulate the doorway from the basement. Insulate the ceiling as described in Open foundations, as well as Figure 6-11.

If you insulate your cold cellar, check on the winter temperature so you can make adjustments to prevent freezing. If the room is still too warm or the floor above is cold, you may want to insulate the ceiling of the cold room (see Open foundations).