Location of Air/Vapour Barrier
Location of Air/Vapour Barrier
In order to maintain the integrity of the insulation, a full, continuous air/vapour barrier must be maintained. Its location can vary, with two common placements listed below:
Standard Location: Typically, the air/vapour barrier is placed on the warm side (in the winter) of the insulation. The insulation is placed in the wall cavity and covered with a fully sealed a/v barrier which is then covered with the interior finish.
Ideal Location: Interestingly, the optimal placement is with 2/3 of the insulation on the cold side, and 1/3 on the warm side of the a/v barrier. This allows the electrical fixtures to be placed without creating any electrical penetrations and eliminates any condensation that might occur due to temperature differences.
Installation of Air/Vapour Barrier
The air/vapour barrier must be fully sealed in order to be effective. The primary concern is at joints and at structural intersections. The a/v barrier is held in place by staples placed approximately 150 mm apart and the joints are sealed with caulking.
When installing the a/v barrier at an inside corner, a small amount of slack should be provided to allow the panelling to sit tight into the corner without putting any strain on the a/v barrier.
If the a/v barrier becomes damaged during the construction process, small holes can be repaired using the proper tape. Larger holes should be patched and sealed with caulking.
When the a/v barrier is interrupted at openings, there are two methods of sealing:
Review Questions – 3.02.4
Use the CHBA Builder’s Manual and the Carpentry textbook to answer the following.
- List some ways to construct walls to ensure the air/vapour barrier is continuous behind partition walls where they meet exterior walls.
- Wires passing through top plates and end studs must be:
- Describe how the vapour barrier is installed around an electrical box in an exterior wall.
- Besides adding more insulation, list some ways the performance of roofs and attics can be improved.
- Describe two methods of maintaining a continuous air/vapour barrier across the top of interior partitions.
- How is wire that passes through the top plate of interior partitions sealed?
- Describe how to build an attic hatch for a proper seal to the air/vapour barrier.