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gerry_foster
basement bathroom ceiling question

hello all! i'm new to this forum, hope to get some helpful info as well as help others with my experience.

I live in Ontario Canada,

we are adding a bathroom to our finished basement, however I have some questions about the ceiling and whether it needs to be vapor barriered from the main floor?

a few things about my basement to give you an idea what im working with....

-65 year old bungalow
-5 years ago complete excavation to exterior to membrane and re-tile drain
-entire inner envelope has 4" wall tite eco spray foam directly on cinder blocks and all sill voids.
-The finished rec room has a drop ceiling with no insulation.
-seperate laundry room/ mechanical room has unfinished celing with no insualtion
-the bathroom is going in a far back room that at one time was an addition to the house, so this is divided by a cinderblock wall with a 36" door opening.

so my bathroom will be very commercial type, all tile floor to ceiling, 55" square schluter kerdi type shower with no door, 1/2 wall with glass to the ceiling on the only wall of the shower.

all saniflo above slab plumbing (sanistar wall mount toilet, sanishower pump for shower and sink)
-schluter line drain in the shower with a U.K. only horizontal outlet to connect with the sanishower.

Now that you have an idea what im up too, here is my question.

the ceiling.....do i need to poly vapor barrier this to keep the moisture from entering the 2x10 main floor joist area? the ceiling is planned to be t and g cedar unfinished with a panasonic fan direct to the sill plate outside (4')

and if the ceiling has to be poly'd do i do the walls as well to seal the entire room?

-one other thing, all wall are cbu over 2x4 and 2x6 (toilet wall) the shower is Kerdi board with kerdi line single slope floor pan....

Any advice would be greatly appreciated :) hopefully this is not too confusing, just want to have all my cards on the table so as to not create alot of other questions. Cheers, Gerry

gerry_foster
Re: basement bathroom ceiling question

could I have this moved to the ceiling section? thanks. G

keith3267
Re: basement bathroom ceiling question

As long as you have an exhaust fan to remove the excess moisture when running the shower, you will be OK. The space above is heated. It would be different if the space above was not in the HVAC envelope. You might have a concern where the exhaust fan exits the rim joist area, you want to make sure that moisture doesn't condense there and migrate back into the wood of the rim joist. A really good coat of paint needed and must be maintained. If you can extend the exhaust a couple inches out from the wall, that would help some.

dj1
Re: basement bathroom ceiling question

It won't hurt to put plastic between the CBU or drywall and the wall/studs/joists.

gerry_foster
Re: basement bathroom ceiling question
keith3267 wrote:

As long as you have an exhaust fan to remove the excess moisture when running the shower, you will be OK. The space above is heated. It would be different if the space above was not in the HVAC envelope. You might have a concern where the exhaust fan exits the rim joist area, you want to make sure that moisture doesn't condense there and migrate back into the wood of the rim joist. A really good coat of paint needed and must be maintained. If you can extend the exhaust a couple inches out from the wall, that would help some.

Thank you Kieth, i will see what i can fabricate for an outlet on the Fan to move it as far out as possible from the wall/rim joist.

Cheers, Gerry

keith3267
Re: basement bathroom ceiling question

I should add that where the duct comes through the rim joist and fascia, it should be caulked in place so that condensation can't come out the end and run along the bottom and back into the fascia and/or rim joist. A slight downward dip in the duct or a lip on the end so that water can drip off the end would also work.

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