Vapor barrier / Discussions

Where should I put an air barrier on a log home insulated from the outside only?

...barrier location if perfect. I would point out that some air barrier materials allow moisture to pass, and some stop it. to install an air barrier on the outside of the insulation you need to be sure not to trap moisture, so be sure you have a vapor permeable membrane, read more here - Choosing the Right House Wrap / W...

Posted by Geneviève Rock Dec. 5, 2025 Air and vapour barriers 1 response

How to deal with condensation in basement?

...vapor barrier between the concrete walls and the 2x4 studs. The space behind the rim joist is insulated with 1" rigid foam (the pink stuff) and then covered by a very thin layer of spray foam. I plan to keep the current vapor barrier and wood studs for financial reasons, put mineral wool between the studs, then cover i...

Posted by Shane Hu Aug. 7, 2025 Basements improvements 1 response

How do I prevent attic moisture build up in winter?

...barrier is properly installed and not modified. I got a bit of leakage in the spring through my master bathroom ceiling.  I have a 6/12 pitch roof with gables at front and back. The buiding code where I live was changed a few years back and does not allow vented soffits within 4 ft of the property line, so my soffits a...

Posted by Steve Jensen July 9, 2025 Walls and Roofs

Do you need a vapor barrier between the attic and living space?

...barrier, should a vapor barrier (non permeable) be used to hault moisture flow between the attic and living space. Thinking permeable is better but I'm hearing differently. Where and when to use vapor barriers in construction and renovation can vary depending on a few things – the climate you are building in, whether i...

Posted by Jim Williams April 25, 2023 Air and vapour barriers 3 responses

When do you use air barriers, vapor barriers and radiant barriers?

...vapor barrier in very cold climates, an exterior vapor barrier in hot and humid climates, and possibly vapor retarders in that grey area between the two.  I don't know your exact location so I would check with the local building authorities, but for cold climates you would want an interior vapor barrier. Taking care to...

Posted by Brandon Churchill July 19, 2023 Air and vapour barriers 1 response

Is there anything I can do about a vapor barrier on the wrong side of a basement wall?

...vapor barrier without tearing out the whole wall? I've read enough of the basement articles to know that on a new wall I should put a vapor barrier right against the foundation, then the wall assembly. Ideally with a perimeter drain as well. But this isn't new and that's not gonna happen for a while. Thanks! Putting va...

Posted by Iain B Feb. 8, 2021 Basements improvements 8 responses

Where is the correct vapor barrier location in Chicago?

...vapor barrier also be the air barrier? There is a difference between the two, read more here first –  The difference between air barriers and vapor barriers If you plan to have an additional air barrier, for example a house wrap or Tyvek at the bottom (which would be my preference, then the options open up for how to ...

Posted by Joel Peerson Jan. 31, 2021 Air and vapour barriers 2 responses

Which is the best basement ceiling insulation?

...vapor barrier on the house side (not pointed downward toward the basement). I want to had additional insulation, especially over the unheated garage. Is wool insulation over the existing fiberglass recommended, or should I simply add unfaced fiberglass insulation? Thanks, DB

Posted by David Boone Jan. 9, 2021 Basements improvements

Is spray foam a good way to insulate a house from the exterior?

...vapor barrier behind our drywall but doubt it - this is an older wood framed bungalow. In addition, i dont expect our interior drywall forms a very great air barrier either - we have the usual holes from outlets etc but we have a lot of windows and other installations - all done seemingly DIY so I have no idea if they ...

Posted by Simon Levitt Dec. 21, 2020 Wall assemblies - renovation 1 response

What is the best way to do a basement renovation?

...vapor barriers was originally to prevent moisture accumulation and damage in walls, which it does above grade, but below grade a vapor barrier CAUSES moisture accumulation and rot. It’s a bit late now I guess, but what you should probably do if you can is see about cutting holes in the vapor barrier to let the moisture...

Posted by BIG FOOT Nov. 18, 2020 Basements improvements 1 response

Where does a vapour barrier go when building a shed in southern Ontario?

...vapor barrier that satisfies building inspectors (as it looks the same as any poly vapour barrier) but it will also let moisture escape. It’s called certainteed Membrain, and when too much humidity builds up, it actually has pores that open and let some moisture escape. But keep in mind, interior vapour barriers are on...

Posted by Charley Nelson Nov. 5, 2020 Wall assemblies - new construction 1 response

What is the best way to insulate a concrete block house?

...barrier.  Then stud out the inside and R13 insulation then dry wall. Thoughts? What is your climate zone? Experiencing tornadoes is a clue, but closer is better. A foil bubble wrap will for sure act as a vapor barrier, but that should only be installed in a cold climate, so I’m assuming you’re a bit to the north. Foil ...

Posted by kent wardecke Oct. 17, 2020 Foundation and basement improvements 2 responses

Should I vent the space between a block wall and vapor barrier?

...vapor barrier using 6 Mil plastic and hold the new walls a few inches off of the block. I am worried about the moisture that makes it past the Drylok and it stoped by the vapor barrier. I have no french drain or any drain sytem. I believe Im right when saying that that space between the block and barrier has to breath ...

Posted by Nick Santore Oct. 10, 2020 Basements improvements 1 response

Should you allow air flow through a crawl space with a dirt floor?

...barrier on the ground, but the rest is a little suspect to me as it is to you. First though I would point you to this page in case you haven’t seen it yet, it discusses the issues with crawl spaces and how they are best insulated and kept dry. Crawl Space Insulation Tips for Insulating Crawlspaces Properly So a few que...

Posted by Amber Murray Aug. 17, 2020 Crawl spaces 3 responses

The thickness of vapor retarding latex paint - Is measurement wet or dry?

...vapor retarder primer (vapor barrier paint) in our Edelweiss LEED Platinum Demo House instead of a 6 mil poly vapor barrier, it was for the walls not the floor. As for thickness, that is what we would call a bit of a concern with using it as a vapor barrier, it is harder to be sure there is consistency of coverage. Our...

Posted by Kim Boas July 24, 2020 Basements improvements 3 responses

How would I rectifiy problem of foundation wall cracks with finished basement?

I have a cinderblock foundation in my house built in central east Ontario in 1983. In 1999 I finished the basement, with tar paper against the cement wall, then studs and four inches of batt insulation and then a vapour barrier and drywall. Two years ago I noticed cracking on the exterior of some of the foundation bloc...

Posted by Terry P July 22, 2020 Basements improvements 3 responses

What is the proper location of a vapor barrier in a home in New York State?

...vapor barriers and insulation.  I live in update NY, our home was constructed in 1952.  We are adding a full shed dormer with 2x6 walls and 2x12 rafters.  Our plan is to use closed cell in the walls and ceiling - which will have a copper standing seam roof.  Code requires a Tyvek type outer wrap, but we want to conside...

Posted by Michael Boice Jan. 15, 2022 Air and vapour barriers 2 responses

Fill gap between wood stud wall and closed cell foam or fill the stud bays?

I'm adding insulation to the stud walls in my baserment with 2.25" of close cell spray foam on the concrete walls.  The stud walls are 3-5" " from the close cell spray foam.  I can either (try to) pack the void between the wall and the uneven surface of the closed cell spray foam, leaving the stud bays empty, or leave ...

Posted by B Mac Dec. 13, 2021 Wall assemblies - renovation 3 responses