Interior insulation refers to any type of thermal insulation which is installed on the inward-facing side of a building's structural walls or structural framework. As it is generally exposed directly to interior spaces in storage areas like attics, it is generally covered with an inner wall of some kind, such as drywall. This is possible in conjunction with any facade system.

The position is relative to the load-bearing wall or framework. The insulation lies toward the interior, whether exposed in a storage area or concealed behind an inner lining.

Exterior insulation occupies the opposite side of the structural wall or frame. The insulation's position is separate from the substance and physical form used to make it.