Sealing junction between ceiling drywall sheets
longfieldl
| Posted in General Questions on
Hi,
I am about to air seal my attic. I will use caulk and polyurethane spray cans to seal air leaks around pipes, electric boxes, chimney, top of walls, … I was wondering if the junction between the ceiling drywall sheets should also be sealed. Using caulk or polyurethane seem a little overkill (quite a lot of junction to cover $$$) to me and I was wondering if using waterproof paint in those junctions would be a good idea. In the end, I would like to seal all the air except the slow movement of air coming through the drywall itself.
Thank you
Louis
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Replies
Longfieldl,
Have you read this article? It outlines best practices for air sealing an attic floor: https://www.greenbuildingadvisor.com/articles/dept/musings/how-insulate-attic-floor
Top plate to drywall juncture can leak alot, especially without poly which wont go over well in the non poly forum this is but its true, houses without poly sieve air on the ceiling plane compared to houses without when tested. I use 1 component foam.
I would not use a waterproof paint.
Louis,
I don't see any point in trying to seal the taped and mudded joints between the drywall sheets on the ceiling. Unless they are cracked (and then you have other more pressing concerns), they should not allow air to move through them. If all penetrations have been sealed, the next biggest source of air making it's way into the attic is typically from between the interior stud-walls and their drywall. Unfortunately all the easy ways of air-sealing them can only be done before drywall, either by applying caulking or gaskets to the top plates before boarding or, as T. Carlson said, using poly. I agree with him that whatever the knock on poly, one of the situations where it makes the most sense is on ceilings below attics.
I thought op was talking drywall ceiling to top plates.
I agree with malcolm, no point in the field seams of drywall.
T,
I may have mis-understood the question. Wouldn't be the first time.
Thank you very much. Yes, I was more talking about the joints between drywall sheets than about top plates. You guys have provided good answers. I do have some tiny cracks between sheets in this 60 yo ceiling which are most likely due to house movements and circulation in the attic. I will focus on sealing those from below, which will improve the look and block the air.
Thanks
Louis