The thermal barrier protects the envelope from heat loss/heat gain. Basically, it is the blanket that keeps a house warm.

Some materials are better at slowing down heat flow than others. Insulation is used in a home to slow down heat transfer. The purpose of the thermal barrier is to keep the heat in the home longer during winter, and keep the heat out longer in the summer.

A main source of heat loss within the building envelope is through conduction; all walls, floors and ceilings which separate a heated area from an unheated area require a thermal barrier ( e.g. Insulation) to be installed. Insulation allows a home to retain heat in the winter and remain cool in the summer. The greater the amount of insulation, the less heat transfer occurs. The minimum amount of insulation that is required within a building is determined by the climate and the local codes for a given location.

Thermal control criteria:

• Installed within cavities or on the exterior or interior surface
• Resistance to heat flow (the higher the R-value, the slower the rate of heat loss)
• Minimum R-values are required by OBC depending on a buildings location and climate

Refer to SB-12 and the OBC as it requires one of the three following values to be met for insulation levels:

1. Minimum nominal R-value
2. Minimum effective R-value
3. Maximum U-value

Materials:

Insulation can be a variety of materials.

Placement/Location:

• Slab/foundation
• Below grade walls
• Above grade walls
• Headers
• Overhanging/exposed floors
• Attic/roof
• Shared walls and ceilings of an attached garage

Improperly installed Insulation can cause major heat loss issues for a building. This can greatly increase the cost of heating the home and may also cause occupant discomfort. Failure of this layer is caused by water ingress which significantly reduces the ability to control heat flow.