6-mil poly vapour barrier for basements, crawl spaces, and new wall assemblies. Free on-site quotes, call (343) 459-3623.
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What a Vapour Barrier Does and Where It Goes
A vapour barrier is a continuous sheet, usually 6-mil polyethylene, installed on the warm side of an insulated assembly. Its job is to slow the movement of warm, humid indoor air into a cold cavity, where that moisture would otherwise condense on cold framing, concrete, or the back of your drywall. In an Ottawa winter, the temperature difference between inside and outside is large enough that this condensation risk is real in any uncontrolled cavity, which is why the barrier’s placement, seams, and seals matter as much as the insulation itself.
Where We Install Vapour Barrier
The same material, applied to a few different assemblies.
Basement Stud Walls
Installed over basement wall insulation before the drywall goes up.
Crawl Spaces
Ground coverage and wall coverage in a crawl space to control moisture rising.
New Walls & Over Exterior Rigid Foam
Installed as part of a new build or renovation. Placed correctly relative to rigid foam board so the assembly does not trap moisture.
Installation Details That Matter
Continuous Coverage
Gaps or missed sections defeat the purpose of the barrier.
Sealed Seams, Overlaps & Penetrations
Where sheets meet, seams are overlapped and sealed rather than just taped edge to edge. Outlets, pipes, and other penetrations through the barrier are sealed individually.
Correct Side of the Assembly
Vapour barrier belongs on the warm side of the insulation. Placing it on the wrong side traps moisture instead.
Vapour barrier work is priced by the area covered and how much of the space is already open versus finished, so there is no single per-square-foot number we can quote without seeing the space. We confirm pricing after a free on-site assessment.
Get Moisture Control Done Right
Free on-site quotes for vapour barrier installation across Ottawa.
Ottawa Insulation Experts provides professional vapour barrier installation throughout Ottawa, Ontario. We install 6-mil poly vapour barrier in basements, crawl spaces, and new wall assemblies for homeowners finishing a basement, renovating, or building an addition. Done correctly, it controls the moisture that would otherwise condense inside a cold cavity; done on the wrong side of the wall or with gaps in the seams, it can trap moisture instead. We detail the seams, overlaps, and penetrations so the barrier actually does its job.
Vapour Barrier FAQs
Where exactly does the vapour barrier go relative to the insulation?
It goes on the warm, interior side of the insulation, between the insulation and your drywall or interior finish. That placement is what allows it to slow moisture before it reaches a cold surface.
Do crawl spaces need vapour barrier on the ground, not just the walls?
Yes. Ground coverage in a crawl space controls moisture rising from the soil, which is a separate source from humid air moving through the walls, so both are addressed together.
Can vapour barrier be added to a basement without removing existing drywall?
If the wall is already finished, we assess what is accessible during your on-site visit. In many cases it is more practical to plan vapour barrier work alongside a renovation or a wall you are already opening up.
What happens if a vapour barrier is installed on the wrong side of the wall?
It can trap moisture inside the assembly instead of keeping it out, which is worse than having no vapour barrier at all. Correct placement and detailing is the part of this job that actually matters.
Is vapour barrier required by code in Ottawa?
Requirements depend on the specific assembly and project. We will tell you what applies to your situation during the on-site assessment rather than giving a blanket answer.
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