Common culprits include electrical receptacles and around baseboards. Foam gaskets can be used to cover electrical receptacle plates. Acrylic latex sealants or urethane foam can be used to seal other leakage openings into the attic.

Use small cans of one-component spray foam for most insulating/sealing jobs around the house. For bigger projects, like sealing and insulating the spaces between the second floor joists in a storey-and-a-half house (a major source of air leakage), use large froth-paks of two-component foam.

Air circulation from the soffit is necessary in removing any humid air that might still escape into the attic. Install vents between the rafters so the required air space is maintained, and make sure the soffit itself is actually vented instead of installing vented aluminum soffit panels directly on solid, unventilated wood soffits.

Unless specifically designed for such use, don't directly insulate recessed potlight fixtures. Doing so can cause heat to build up, which can create a potential fire hazard. The construction of an airtight drywall box around the fixture is a good way of allowing heat from the potlight to dissipate.

A filtered drainage layer is especially useful in fine-grained soils where water can run through faster than normal. A filter cloth, during the service life of the building, can prevent fine soil particles from accumulating behind the drainage layer, which reduces the chances of water leaking into the basement.

Exterior insulation is the better approach, as interior insulation can cause condensation on the basement wall. To prevent studs and strapping from deteriorating, keep them away from direct contact with the basement walls by installing extruded polystyrene insulation to the back of studs, or even to the entire wall. You can also keep the bottom plate off the basement floor and keep the drywall about 50 millimetres off the floor.

When it comes to the interior of a block basement wall, don't insulate it in frost-susceptible soil, like silt. Interior insulation will cause the block's exterior to be cold, and adfreezing (soil frost adhering to the block's exterior) can occur. The combination of frost heave and adfreezing may cause the blocks to displace.

When it comes to insulating and air sealing projects, think of more than just cost savings to justify the expense. Having quality insulation and air sealing in place also means many years of comfort ahead of you.