What is a vapour barrier / Guides

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

Replacing polyethylene vapour barriers with latex paint vapor control

...anding vapor barriers: The National Building Code of Canada stipulates that for residential buildings, a vapour barrier must have a water vapour permeance of less than 60 ng/Pa*s*m2 or 1.0 Perm. That means that no more than 60 nanograms of water vapour can pass through a square meter of the material in one second. Na...

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

Interior sheathing as an air and vapour or vapor barrier

...a material qualifies as a vapour barrier is determined by the amount of moisture that passes through it, and it is given a rating. Any material that allows less than 60NG (nanograms) of moisture to pass through under specific conditions, is considered a type 9 residential vapour barrier by the National Building Code. ...

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

What is an air barrier?

...ately 100 times more water vapor is carried into our walls by air leakage than is carried by vapor diffusion. That makes air 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 barrie...

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

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

...at weather barriers are often intended to act as an air barrier as well, but the most common installation techniques (staples, nails and hastily installed tape) mean it is a rare case when they actually do a good job at air sealing. Manufacturers will rightly claim their products are a suitable choice for an air barrie...

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?

...and 1 perm, a material is classified as a type II 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 t...

Off grid, passively heated and cooled house in the Gatineau Hills, Que
Off-grid and Net-Zero Housing

Off grid living blog, part 2: passively heated, this house in Quebec aims for LEED certification

...ace as many of them south as you can to gain heat, and install heavy duty insulation to keep that free heat. Further to that, the house is powered by solar panels, and heated by a woodstove and radiant floors warmed by a propane boiler. A double exterior wall system reduces heat loss to a fraction of what you would e...

Basement Design for walls prevents mold & midlew when renovating & finishing
Healthy indoor air quality

Basement renovations: How to prevent mold when finishing basements

...an even and total protection. SPUF has a high R value per inch, acts as an air barrier and a vapour barrier. However, it has been known to shrink after application, leaving air gaps and a lack of thermal protection. Another downside to the original SPUF is that some blowing agents have a high global warming potential...

Finished basements can lead to mold and mildew
Healthy indoor air quality

Why are basements moldy? How to fix or Prevent a Moldy Basement

...an even and total protection. SPUF has a high R value per inch, acts as an air barrier and a vapour barrier. However, it has been known to shrink after application, leaving air gaps and a lack of thermal protection. Another downside to the original SPUF is that some blowing agents have a high global warming potential...

Choosing a building envelope
Wall assemblies - new construction

Choosing a building envelope - starting with the perfect wall

...ay or which route has the most gas stations or least amount of hills. So what is the best wall system? That also depends on what you are looking for. What is the most durable wall? What is the most energy efficient wall? What is the most soundproof wall? What is the most affordable wall? That is just a short ...

Installing foam panel insulation, which is best?
Insulation and soundproofing

Rigid insulation panels: which ones to use for different applications

...as into your home. That means it can lead to cleaner indoor air quality, and the R value will never change, whereas foam products will deteriorate over time as the gases escape. Mineral wool is rated at about R 4, it is unharmed by moisture, it is not a vapour barrier at any thickness, nor is it an air barrier. It al...

Step by step guide for slab-on-grade home construction
Slab on Grade

Slab-on-grade construction: the ecoHOME A to Z Slab building guide

...AS EVACUATION with a slab on grade foundation: Radon is a naturally-occurring radioactive gas that is produced when uranium that is present in the earth's crust starts to disintegrate. The gas infiltrates houses through cracks in the slab. Radon exposure is linked to roughly 16% of lung cancer deaths in Canada, and i...