Vapour barrier / Guides

Interior sheathing as air & vapor barriers in wood frame construction
Air and vapour barriers

Interior sheathing as an air and vapour or vapor barrier

...vapour barrier. Ideally we'd have no vapour barrier in summer; but short of that we should at least have one that allows as much drying to the interior as possible without sacrificing its winter performance. So the closer your vapour barrier is to 60NG, the better. For the sake of context it should be noted that poly...

Exterior air barrier membrane © Ecohome
Air and vapour barriers

How to install an air barrier for reduced air leakage

...barriers and vapour barriers: The job of a vapour barrier is to prevent vapour diffusion and the job of an air barrier is to stop air leakage through differences in air pressure between inside and out. A wall system should have one vapour barrier, but can have many air barriers. A vapour barrier can act as a very eff...

Vapor retarder latex primer instead of polyethylene sheet
Air and vapour barriers

Replacing polyethylene vapour barriers with latex paint vapor control

...vapour barrier is mistaken for, and almost entirely relied upon to act as the air barrier. The purpose of the two barriers should not be confused - the job of the vapour barrier is to control vapour diffusion, the job of the air barrier is to control air leakage. 6 mil poly can work effectively as an air barrier if i...

Air barriers are essential to a properly functioning wall system
Air and vapour barriers

What is an air barrier?

...barriers 100 times more important than vapour barriers, so why is no one talking about them? We don't talk about air barriers because we are too busy talking about vapor barriers. An air barrier is not something you walk into a building supply store and buy; it is a design concept, and arguably a commitment. Products...

Radon and vapour barrier below slab on grade floor
Healthy indoor air quality

Vapour / radon barriers below slab floors

...vapour barrier, we used a 10 mil barrier and a radon evacuation stack to lower radon gas levels in homes, research shows (see below) that thicker membranes offer more effective protection. In this video we are installing a 10 mil vapour barrier but we would probably use a thick vapor barrier like this one in future a...

The difference between air barriers and vapour barriers
Air and vapour barriers

The Difference between air barriers and vapor barriers

...barriers and vapor barriers The job of a vapor barrier is to prevent vapor diffusion, and the job of an air barrier is to stop air leakage through differences in air pressure. A wall system should have one vapor barrier, but can have many air barriers. A vapor barrier can act as a very effective air barrier, but an a...

Tyvek home wrap left exposed to wind and UV rays
Air and vapour barriers

Choosing the right house wrap / weather barrier, which is best?

...vapour barrier. Products rated below those numbers are vapour barriers, those rated between 1 and 10 perms are considered vapour retarders. The higher the perm rating or Ng, the quicker moisture can evaporate. *Ng stands for Nanograms, or billionths of a gram of water. That 60 Ng number refers to the amount of water ...

Better Basement Design on basement walls prevents mold and midlew
Healthy indoor air quality

Basement renovations: How to prevent mold when finishing basements

...vapour barrier. Notice the difference between the studs against the foundation and the studs that formed an interior division wall; the vapour barrier did not protect the exterior wall from damage and mold growth. It caused the damage by prevented the wall from drying to the interior and instead sealed the moisture in....

Choosing between OSB or Plywood for house sheathing for Roofs, Walls & Floors.
Wood and organic materials

Which is better, OSB or Plywood for Roofs, Walls & Floors?

...vapour retarder, which is suitable for use as what is exclusively known as a 'vapour barrier' on a work site, the standard 6 mil polyethylene. And remember - a vapour barrier goes on the inside of a wall, NOT the outside. Since we intentionally contain water vapour on the interior of a building with a vapour retarder, ...

Insulating crawlspaces as part of home renovation
Crawl spaces

How to insulate crawlspaces properly as part of renovating an older home

...vapour barrier © For those with nothing but a dirt floor, the single most important thing to do will not cost much - cut off the moisture supply to the air by laying down polyethylene directly on the ground. The standard 6 mil poly vapour barrier will work fine as a DIY solution. Do the best job ...

Building science for LEED v4 wall design made easy
Concept and design

Building science for LEED v4 wall design made easy - video

...barrier from the assault it would normally receive from wiring and other penetrations when we rely on an interior polyethylene as an air and vapour barrier. See our pages on vapour and air movement & the difference between air & vapor barriers to get a better idea of how this works, and why it makes so much sense to bu...