INSULATION SOLUTION: EXTERIOR APRON INSULATION

Insulate foundation walls on the exterior side (and not the interior)
whenever you can. The easiest way to accomplish this is by installing
insulation in the apron area only, so you do not have to excavate all the
way to the bottom of the wall. By adding a layer of horizontal insulation in
the bottom of the trench, you can realize at least 70 percent of the energy
savings of insulating the whole wall, while limiting your digging to 18
inches down and 24 inches out.
Because you will be adding width to the foundation wall by installing
exterior insulation, you will need to install flashing to cover the top of the
insulation layer and whatever protective wall surface you cover it with.
For
the project shown here, the insulation is covered with panelized veneer
siding over 1-inch-thick rigid foam insulation boards. For extra protection,
coat the cleaned walls with a layer of bituminous coating before installing
the insulation boards.

Apron insulation is an easy and effective way to enhance comfort in your basement
without causing any major moisture issues.