Vapour Barrier Installation Delwood Edmonton

Poly and air sealing in Delwood before the board goes on

A vapour barrier only works as a continuous plane. In Delwood 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.

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

Vapour Barrier Installation Delwood Edmonton

What a vapour barrier is not

Delwood drywall in context

Warm side, always

Never two barriers

Top plates, bottom plates and the perimeter

Windows, doors and the returns around them

Where the barrier meets the ceiling and the floor

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

Vapour Barrier Installation Delwood Edmonton: your questions answered

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.

Is a basement wall done the same way as an upstairs wall?

No. A basement wall can take moisture from the ground too, so poly detailed like an above-grade wall can trap moisture against the concrete. The insulation is held off the concrete so the wall can dry, with vapour control on the warm side.

Should I use poly or a smart membrane?

Most straightforward Delwood walls are fine with 6-mil poly, continuous and sealed. A variable-permeance membrane is worth it on retrofits and some basement details because it gives the assembly a drying path in both directions.

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.

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.

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.