On which side should the vapour barrier be placed?

The vapour barrier should be placed on the warm side of the insulation. This is crucial for preventing condensation from occurring within the building envelope. When warm, moist air from inside the building comes into contact with cold surfaces, such as exterior walls, it can lead to condensation. This moisture buildup can cause serious issues, including mold growth and damage to the building structure.

By placing the vapour barrier on the warm side, it acts as a shield that prevents moisture-laden air from moving through the wall assembly. This ensures that any moisture that may inadvertently reach the cooler surfaces is kept away from these areas, thereby protecting the integrity of the building materials and maintaining a healthy indoor environment.

To highlight, the vapour barrier’s position is strategic; it is specifically meant to manage the movement of moisture and mitigate the risks associated with condensation.