Insulating the foundations and insulating the roof of your home will help it withstand extremes of cold or heat while maintaining a comfortable indoor temperature, thereby avoiding exorbitant energy bills. Without adequate insulation, your home risks losing a substantial amount of its heat as follows:

  • 17% through the above-ground walls;
  • 15% through the underground walls and the foundation footings;
  • 11% through the roof.

Poor insulation is also responsible for cold floors and walls, condensation at the wall base and the proliferation of mold. Insulating your home can make a big difference.

Procedures & Materials
There are various types of insulating materials: rigid foam panels, fibreglass batts, loose cellulose fibre, injected and foam insulation. To be effective, the insulating material should:

  • uniformly fill the space to be insulated;
  • be resistant to heat transfer;
  • be long-lasting;
  • resist humidity (in certain cases).

Its thermal resistance or R factor (RSI, in the metric system) indicates an insulating material’s performance. The higher the R or RSI value, the more resistant it is to heat transfer and the better it is as insulation. Nevertheless, regardless of the material chosen, its installation must be faultless, for its thermal resistance depends on it being properly installed. When selecting an insulating material, the first consideration is what use it is destined for, rather than its thermal resistance (R) or cost. For example, certain materials are not suitable for insulating a basement but are perfect for insulating the attic.

Is your house well insulated?
Do you have plans for construction or renovation projects? Here are a few important things to consider when carrying out the work:

  • Insulating your house from the basement to the attic will not only eliminate the problems of cold floors, condensation and mold, but will also reduce your heating costs.
  • Pay special attention to structural components during any construction or renovation project.
  • Install the insulation in continuous, seamless fashion on the surface of studs supporting the exterior walls, and the floor joists of overhanging beams.

Insulation that has been well planned and installed in your construction or renovation project will make your home more comfortable and reduce your energy consumption.

How should I insulate a concrete basement wall?

Insulating from the inside

Insulating or adding to the existing insulation of a foundation wall from the inside increases the risk of freezing. If the ground is damp and the foundations are close to the frost line, it is best to keep the foundation footings warm by leaving a space at the base of the wall that is not insulated.

Check for any cracks that might be the source of water infiltrating from the outside. The humidity caused by condensation during the summer is apparent in black stains at the base of the wall, while water infiltration from the outside is apparent in deposits of mineral salts on the wall.

The thermal resistance of a foundation wall should be between R-10 and R-15. Use water repellent insulation. The best material is styroplastic foam (Type 3 or 4), but it must be covered with a fireguard as quickly as possible. Mineral wool or fibreglass batts give good results as long as the insulation is protected with a damp-proofing membrane.

Insulating from the outside

If the perimeter drain needs to be repaired, take advantage of the occasion to insulate the foundations from the outside. Stone and concrete block foundations must be insulated from the outside.

After excavating the foundations down to the footings, use rigid foam board insulation (Type 4) that is at least 50 mm (2 in.) thick and extend it to the full height of the wall and on top of the footing. The insulation must be protected from the rays of the sun. Use a water repellent membrane and premium granular backfill to keep the foundations dry. In terms of comfort, as long as you remove the inside insulation, the thermal mass created by the concrete is equivalent to that of an old hot water system.

Source: Agence de l’efficacité énergétique du Québec