An interior insulation retrofit is best performed in conjunction with other interior demolition or remodelling work. A double-stud approach can be used to ensure the wall cavity is deep enough to achieve adequate wall R-value, and to avoid excessive thermal bridging. The main focus with all interior insulation retrofits is making the interior plane properly airtight and closed to vapour diffusion, as deep stud walls present a relatively high risk of condensation on the exterior sheathing.

The following design considerations are for a double-stud retrofit. The information is meant to give an overview of the wall assembly and work required.