Insulation and thermal resistance

The primary role of insulation in a building is to withstand the transfer of heat through the building envelope. Insulation must keep the heat inside the building and this resistance to heat transfer to the outside is defined as "thermal resistance".

When a building is poorly insulated, there are revealing clues such as:

  1. Floors and walls that are cold;
  2. Heating costs are high compared to a building of the same size well insulated;
  3. A significant variation in the temperature of the surface (floors and walls) in the same room;
  4. Condensation and mold in the structure of the external walls;
  5. The interior is very hot, during the summer, and the high air conditioning costs as well as the difficulty of air conditioning the space.

Types of insulation

There are several types of insulation that are used, among others:

  • Mattress insulation (mattress);
  • Cellulosic fiber;
  • Mineral wool;
  • Fiberglass;
  • Mineral fiber;
  • Expanded or extruded polystyrene;
  • Rigid fiberglass
  • Rigid mineral fiber
  • Polyurethane spray, etc.

Using an infrared camera (thermography), we detect the problematic points with respect to the insulation in the external envelope of the building (the points of thermal losses in the envelope). We also use exploratory holes in the identified areas to examine insulation that may be damp, compacted, improperly installed, inadequate or absent.

Condensation and heat losses

Condensation in the structure is the most common problem when insulation is improperly installed or improperly installed. However, it should be noted that theisolantion is not the only one responsible for the problems of condensation and thermal losses in the building envelope. In fact, there are components that play an important role, such as air barrier and the vapor. The air barrier is on the outside of the wall and the vapor barrier on the inside of the wall.

An improperly installed air barrier allows cold air to enter the structure and cause condensation in the structure. While a poorly installed or absent vapor barrier leaves the interior moisture penetrate into the structure and causes a problem of condensation.

The air barrier and vapor barrier must be properly installed, according to the rules of the art, for the envelope to be effective and function as an integrated assembly. The aim is to ensure the thermal comfort of the occupants and to prevent the formation of mold, condensation and rotting of the wood of the structure.

Building envelope

At the time of construction, it must be ensured that the components that form the building envelope have the adequate thermal resistance stipulated in the current Quebec Energy Code.

A building expert should be consulted to calculate the total thermal resistance of the exterior wall components and to ensure that the condensation (dew point) does not occur in the wood structure of the exterior walls. This is to prevent rotting of the structure and the formation of molds and the problems associated with them, such as carpenter ants, infiltration of air or water by the rotten structure, the smell of mold and rotting. etc.

Condensation behind the wool insulation

Condensation behind the wool insulation


Extruded insulation deteriorated by carpenter ants

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