Air/vapor barrier question
bdrfab
| Posted in Green Building Techniques on
My house was built in the 50’s, and as is typical for homes in this area, has 1/4 drywall with a real plaster job over it. My question is is this a better/worse/same air/ vapor barrier than standard drywall, taped at seams etc. I’m asking because I’m a little concerned about trapping moisture in the wall now that I’ve added 5 1/4″ or EPS to the exterior. Thanks.
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Replies
Aaron,
Neither taped drywall nor plaster-over-drywall leak air in the field of the wall; however, either type of wall finish can leak a lot of air at the perimeter (especially the bottom of the wall), at penetrations (around windows and doors), and at electrical boxes.
So, if you want a good air barrier, you're asking the wrong question. It's not a question of taped drywall versus plaster-over-drywall. It's all about air sealing at edges, penetrations, and electrical boxes.
If you are renovating an existing house, it's possible to improve the airtightness of an existing wall by removing the baseboards, window trim, door trim, and electrical cover plates so that all of the cracks can be caulked. This will improve the situation, but you won't end up with a perfectly tight wall.
Cool. I know there's no poly, so I should be good then. Thanks Martin, as usual.