There are three ways to install the insulation:

• from the inside
• from the outside
• from the basement/attic

i) From the inside

Small holes of 15 to 50 mm (? to 2 in.) are drilled through the inside wall finish and the insulation is blown or injected directly into the wall. The holes must then be completely plugged and sealed.

If you must replace or re-cover the interior finish, it should be possible to

• drill the holes
• blow in or inject the insulation
• install a well-sealed air and vapour barrier on top of the old interior wall
• apply new drywall and finish

ii) From the outside

Most types of exterior siding can be drilled, lifted or removed to access the stud wall behind. In some cases, brick siding can have single bricks temporarily removed leaving sufficient space to repair holes in the sheathing. Ideally, two stud spaces can be filled from one brick space, though each stud space may require two or more holes with this method. Do not insulate the drainage cavity between the brick veneer and the stud walls. Make sure the installer patches the holes section by section rather than leaving them all until the end to avoid water entry if a storm occurs.

iii) From the basement/attic

This can be the easiest approach if access can be gained and if the cavity is open from top to bottom such as with balloon frame construction. All stud spaces need to be filled, but there should be allowance for windows and doors, fire stops, cross braces and other obstructions in the wall cavity. The contractor will check to see if the wall should be filled from the top, bottom or both, depending on obstructions (see Figure 7-4). After the wall is filled, ensure that the access holes are tightly sealed.