The most common and simplest way to add thermal resistance to an attic is to add attic insulation. The new insulation may be added on top of any existing insulation. However, existing insulation may need to be temporarily moved to allow access to seal at air leakage points before the new insulation is installed.

Insulation baffles should be installed as required to allow for proper attic ventilation. Insulation retention should be provided where blown in insulation is to be installed, to keep the blown-in insulation from falling out of the attic and int o the soffit space.