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.

Should I use poly or a smart membrane?

Most straightforward Prince Rupert 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.

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.

What if there is already a vapour barrier in the wall?

We tie into it, and we check whether there is a second one somewhere that would trap moisture between the two. Older Prince Rupert renovations quite often have both, and finding that before boarding is worth the hour.

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.

Is poly always the right answer?

No. Some assemblies, such as insulated concrete basements or walls with exterior rigid insulation, are designed to dry inward, and poly stops that. We look at the whole assembly rather than defaulting.

Vapour Barrier Installation Prince Rupert Edmonton | 6 Mil Poly

Vapour barrier in Prince Rupert, sealed as a continuous plane

Alberta winters put a large vapour drive from inside to outside, so the barrier belongs on the warm side of the insulation. Getting the position right matters as much as getting it sealed: a second barrier on the cold side traps moisture in the assembly with no way to dry.

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

Sealing at the electrical boxes

Every box is a hole

An outlet or switch on an exterior Prince Rupert wall is a deliberate opening straight through the barrier.

The fix

Poly hats or airtight boxes, sealed to the sheet. Taping the poly to the front of an ordinary box does not last, because the board is fastened over it and the seal breaks. This is the single most common leak we find behind finished walls.

Prince Rupert drywall in context

About Prince Rupert

Prince Rupert lies within the old Hudson Bay Company land reserve.

What we see in Prince Rupert

In Prince Rupert the drywall work is plaster and lath repair, popcorn and stipple ceiling removal, careful patching into original surfaces. We confirm what your home actually needs on site, in writing, before anything starts.

Renovations, and meeting an existing barrier

Continuity across old and new

In an Prince Rupert renovation the new poly has to tie into whatever is already in the wall. A new sheet stopped at the edge of the work leaves an open seam inside the assembly.

What we look for

Whether an existing barrier is present at all, what condition it is in, and whether there is a second one somewhere that would trap moisture between the two. Older renovations quite often have both, and finding that before boarding is worth the hour it takes.

Never two barriers

The trap

Poly on the room side plus a second impermeable layer behind the insulation leaves any moisture that gets in with no direction to dry.

Where it happens

Renovations, mostly. A new barrier gets added over a wall that already had a foil-faced or kraft-faced layer. We look at what is already in an Prince Rupert wall before adding to it rather than assuming the cavity is bare.

Warm side, always

The one rule everything else follows

The barrier goes on the heated side of the insulation. In an Prince Rupert climate that is the room side of an exterior wall.

Why position decides everything

Put it on the cold side and you have placed a moisture stop exactly where indoor humidity will condense against it, inside the wall, where nothing dries and nothing is visible until the damage is done.

Windows, doors and the returns around them

Where the detail gets fiddly

The return between a window frame and the wall in Prince Rupert is awkward, tight, and often left as a torn edge tucked behind trim.

Why it matters

It is also a cold junction where condensation shows first, usually as staining or mould at the reveal. The poly is cut to fit, sealed to the frame and supported, rather than folded and hoped for.

The rim joist and the bottom plate

Two cold junctions

In an Prince Rupert basement the rim joist and the bottom plate against concrete are where warm air meets cold most directly. Both need sealing before insulation, not after.

Sequencing

Once the insulation and poly are on, neither can be reached without pulling the wall apart. We deal with them first, and we would rather flag a problem there at the quote than discover it behind a finished wall.

How it works

Simple, clean, on schedule — Vapour Barrier Installation in Prince Rupert Edmonton

Free quote

We come out to your Prince Rupert Edmonton property, take a real look at the vapour barrier installation, and hand you a fixed price on the spot — no guessing, no vague ballpark. Every vapour barrier installation quote in Prince Rupert Edmonton starts with an honest, on-site assessment.

Book a day

We pick a day that works for your schedule and show up on time, ready to start the vapour barrier installation in Prince Rupert Edmonton. No back-and-forth rescheduling — once it's booked, our team is there.

The work

We keep the dust under control and protect your Prince Rupert Edmonton home while we finish the vapour barrier installation to a clean, paint-ready standard. Floors covered, doors sealed off, and the site left tidy at the end of every day.

Walk it with you

We don't pack up till you've walked the finished vapour barrier installation with us and you're happy with the result in Prince Rupert Edmonton. If anything needs a second look, we handle it before we call the job done.

Reviews

Rated by Edmonton Homeowners

★ ★ ★ ★ ★

Emplastrum Drywall is the vapour barrier installation contractor Prince Rupert Edmonton trusts for repair, restoration and finishing — rated on Google by Edmonton homeowners.

Read the reviews, or leave your own after your vapour barrier installation project in Prince Rupert Edmonton.

Read our reviews on Google

FAQ — Vapour Barrier Installation Prince Rupert Edmonton

Vapour Barrier Installation Prince Rupert Edmonton: your questions answered

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.
Should I use poly or a smart membrane?: Most straightforward Prince Rupert 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.
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.
What if there is already a vapour barrier in the wall?: We tie into it, and we check whether there is a second one somewhere that would trap moisture between the two. Older Prince Rupert renovations quite often have both, and finding that before boarding is worth the hour.
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.
Is poly always the right answer?: No. Some assemblies, such as insulated concrete basements or walls with exterior rigid insulation, are designed to dry inward, and poly stops that. We look at the whole assembly rather than defaulting.

Get Your Free Drywall Quote

Tell us about your project — we’ll get right back to you, 7 days a week. Prefer to call? (403) 829-8702.

Full Name / Company

Phone Number

Email Address

Area

Service Needed

I agree to be contacted by Emplastrum Drywall about my project by phone, text, or email.

No obligation. We never share your information.

📐 Plan Your Project

Estimate Your Insulation

📐 Materials Calculator

How much do you need?

Enter your room size for a quick materials estimate.

Room length (ft)Room width (ft)Ceiling height (ft)Number of rooms Include ceilingSheet sizeCoats of paintCavity depthFraming spacingInsulation already there (in)Top up to (in)Stud spacingDoorsWindowsWaste allowance (%)

Estimate only — rounded up, based on standard coverage rates (drywall +10% waste; paint ~350 sq ft per gallon per coat; batt bundles by cavity depth, less a framing factor; studs at your chosen spacing plus waste). Product coverage varies by brand — confirm quantities before buying. Ask us about the right R-value for your project.

Rather we handle it? Get a free estimate →

Vapour Barrier Installation Prince Rupert Edmonton

Vapour barrier in Prince Rupert, sealed as a continuous plane