1. Remove existing finishes and insulation (if any) to expose the exterior wall assembly. Inspect and repair framing and sheathing as needed.
2. Construct inner stud wall with framing as required, with a gap between the interior and exterior stud wall sized according to the desired R-value. Seal all edges along the floor and ceiling with polyurethane sealant.
3. Insulate stud space with blown-in or batt insulation.
4. Install polyethylene air barrier/vapour retarder and seal all joints and laps, at all penetrations, and seal to the interior framing.
5. Install and finish interior gypsum board as required.

Note: The polyethylene should run across the plane of the interior framing where interior dividing walls intersect with the exterior wall, ensuring air barrier continuity. Alternate materials may be used as long as the air barrier system is continuous.