Insulating walls
	Blown-in insulation
	Renovating the interior
	Renovating the exterior
	Miscellaneous spaces
	Additions and new construction

Insulating Walls

Walls can account for 10 to 30 percent of heat loss in houses. In addition to heat loss through the walls, there are many cracks and penetrations that allow uncontrolled air leakage into and out of the house.

Types of Wall Construction

Solid Walls

Solid walls include brick, concrete block, log and wood plank. These do not have a cavity that can be insulated. The only way to insulate them is to add insulation to the exterior or to the interior. Many solid walls do have a small cavity, generally less than 25 mm (1 in.), that is used to collect and drain water out of the wall. Never insulate these cavities or plug their drain holes.

Concrete Block

Concrete block walls usually have hollow cores that allow air circulation. The cores cannot be insulated effectively, since the block and mortar will continue to act as a thermal bridge. However, air can easily circulate inside the block cores, increasing convective heat losses. Seal all possible air-leakage routes into the blocks.

Frame Walls

Frame walls have a cavity that may be insulated. Different construction techniques determine the size of the cavity and ease of access from either the interior or exterior. The wall construction also affects details that can interfere with the insulation, including top and bottom plates, fire stops, blocking, plumbing, wiring and heating ducts. A frame house with a brick veneer usually has an air space of 25 to 50 mm (1 to 2 in.) between the bricks and the frame wall for drainage. While the larger cavity in the frame wall can be insulated, the drainage cavity behind the brick veneer should never be insulated.

Opportunities for Upgrading

Empty-cavity frame walls are the easiest to insulate. Insulation can be blown in from the top and bottom or from the interior or exterior.

Frame walls with some insulation or solid walls are more difficult to insulate, although they should be air sealed appropriately. They can be insulated as part of a major repair job or renovation. Interior work includes wall repairs, drywall replacement and decorating and any renovation changes to the wall. On the exterior, insulating can be combined with re-siding.

Solve any moisture or structural problems before insulating. Indications of problems include staining, dripping, mould growth, cracks on the inside wall finish and in the exterior siding, and windows and doors that don't operate properly because they are out of square.

It is important to consider vapour barriers and air barriers, especially when extending an existing wall from either the interior or exterior. Keep in mind that in most climate zones, the vapour barrier must be on the warm side of the finished wall. You must also consider the location and condition of old vapour barriers, which could be as simple as plaster walls with several coats of paint.