Wall Insulation

It’s a well-known fact that walls are an important source of heat loss.

As a result, the better you insulate your building envelope, the more you will be able to invest, in the medium term, on something else than house repairs – your RSPs, for example!

Actually, an insulation product such as sprayed urethane foam makes it possible to save on your house structure (e.g., by using 2 x 4s rather than 2 x 6s).

All in all, far from being a luxury, wall insulation is actually a necessity!

Advice from Isolation Majeau

• What type of insulation product?
• Insulating adjoining walls
• Insulating with fiberglass batts
• End joists
• Don’t forget the windows!
• A few tips on insulating windows

What type of insulation?

Many different materials can be used to build walls, and several products can be used to insulate them. A few guidelines for wall insulation:

• Pay special attention to the entire structure and the continuity of the air barrier (to counter infiltration problems) and vapour barrier (to counter humidity problems).
• Since you have large surfaces to cover, you can use conventional insulation for the walls of the first and second floors.
• If you decide to use fiberglass batts, take special care that the installation complies with RBQ standards.
• Carefully cover thermal bridges by using continuous insulation.

Same as for all insulation products, the vapour barrier must comply with the insulation regulations of the Québec Construction Code (2005).

Insulating ADJOINING walls

Tip: Insulate adjoining walls as you would for a separate cottage, and pay special attention to walls made of cement blocks (town houses).

Insulating with fiberglass batts

Although very popular, fiberglass batts is not the only material you can use to insulate walls:

• By using sprayed urethane foam you can – in a single application – avoid thermal bridges and perfectly seal your home’s building envelope, while benefiting from the following advantages:
  • A higher R-value (6 per inch)
  • An air barrier
  • A vapour barrier
• Injecting cellulose into wall cavities is another interesting option.

End joists

It is not uncommon to find insulation deficiencies in end joists. Conventional insulation should be avoided in these areas because of the nearby concrete and the high risk of air infiltration.

Insulating an end joist is particularly challenging because of its shape. The application of 3.5 inches of sprayed urethane foam ensures a hermetic seal, and therefore continuity with the insulation of the foundation and the walls.

Don’t forget the windows!

• Low expansion urethane foam is a good product for sealing off and insulating around windows.
• In lieu of conventional insulation, it is preferable to use sprayed urethane foam to insulate lintels.

A few tips on insulating windows

• Low expansion urethane foam is the right type of product to insulate around windows (from the thermos to the outside)
• Pay special attention to the shims, to block air infiltration
• Check for leaks after application

Also see: wall insulation, basement insulation, attic & roof insulation, floor & ceiling insulation and urethane & polyurethane foam insulation