In hot, dry climates, the thermal mass of masonry walls can be beneficial, absorbing heat during the day and releasing it at night, thereby stabilizing indoor temperatures. However, in most other climates, additional insulation is necessary to enhance thermal resistance.

External insulation can be applied using an Exterior Insulation and Finish System (EIFS), which involves affixing panels of plastic foam to the wall and covering them with a polymeric stucco reinforced with glass fiber mesh. This method not only improves insulation but also protects the masonry from temperature extremes, making it a popular choice for retrofitting existing buildings where preserving the exterior appearance is not a priority.

Insulation within the wall is another approach, involving the insertion of plastic foam slabs against the inner wythe during construction or filling the hollow cores of concrete blocks with foam liners. While effective, this internal insulation does not impede heat transfer through the masonry's solid sections, such as the webs of the blocks or fully grouted areas, somewhat limiting its efficiency.

Insulating the interior surface of masonry walls is also feasible. This typically includes attaching insulation directly to the wall followed by wood or metal furring strips. Interior finish materials, like gypsum wallboard, are then mounted on these strips. This method not only enhances thermal insulation but also creates a convenient void for hiding electrical wiring and plumbing, addressing a common challenge in masonry construction.