Vapour Barrier Installation Elmwood Edmonton

Vapour barrier in Elmwood, sealed as a continuous plane

A vapour barrier only works as a continuous plane. In Elmwood the failures are almost never the sheet itself — they are the electrical boxes, the top and bottom plates, the window returns and the penetrations, where the poly is cut and not resealed.

• Rim joists air-sealed before insulating
• Left ready for inspection before boarding
• Poly on the warm side of the insulation
• Window and door returns detailed properly
• Seams lapped at framing and sealed, not just taped
• Electrical boxes poly-hatted and sealed

Vapour Barrier Installation Elmwood Edmonton

Inspecting it before it is covered

Elmwood drywall in context

What a vapour barrier is not

Renovations, and meeting an existing barrier

Where the barrier meets the ceiling and the floor

Where poly is the wrong choice

Never two barriers

Simple, clean, on schedule — Vapour Barrier Installation in Elmwood Edmonton

Vapour Barrier Installation Elmwood Edmonton: your questions answered

Is the vapour barrier the same as an air barrier?

Not by itself. Poly slows vapour diffusion; sealed properly it also slows air, and unsealed it does very little of either. The sealing is what turns a sheet of plastic into a working assembly.

What about outlets on exterior walls?

Each one is a deliberate hole. They need poly hats or airtight boxes sealed to the sheet. Taping poly to the front of an ordinary box does not last once board is fastened over it, and it is the most common leak we find.

Does it matter where the sheets overlap?

Yes. A lap must land on solid framing and be sealed with acoustical sealant compressed between layers. An unsupported lap taped across a cavity flexes with pressure changes and works loose.

Is a bathroom done differently?

Same rules, larger consequences. A bathroom pushes far more vapour into the wall, so a gap shows up faster. The fan housing and duct are sealed rather than trimmed around, and we check the fan vents outside rather than into the attic.

Why is there staining around my window reveals?

Usually the vapour barrier return at the window was torn or tucked rather than sealed. It is a cold junction, so condensation shows there first — often as staining or mould at the reveal.

Can I add poly over insulation that already has a facing?

Usually no. Two retarders leave any moisture that gets in with no direction to dry. We check what is already in the wall before adding to it rather than assuming the cavity is bare.