Soccer918843
Well-known member
So I’ve finished insulating all my walls and applied a 6 mil vapor barrier question is do I install a vapor barrier to the ceiling too or no a lot of people say no so that it can breath.?
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Rockwool insulation vapor barrier?
- Thread starter Soccer918843
- Start date
I used metal for my ceiling and sealed all the edges it should be a pretty good vapor barrier. It will be interesting this winter to see how my humidity does. Used rockwool in my walls R23 and ceiling R53 Also did 6mil plastic on all the the walls and tape sealed it to the Jchannel for the steel.
If it gets to much i plan to install a small fan with a humidstat to pull out some of the humidity, can also use my heat pump if needed as well.
If it gets to much i plan to install a small fan with a humidstat to pull out some of the humidity, can also use my heat pump if needed as well.
OP
Soccer918843
Well-known member
Damn! R53 I didn’t even know rockwool made anything that big that must of weighed a ton your building is gonna be super efficent I bet I used r 30 in my ceiling and r23 in the walls
banjopete
Well-known member
Not sure where you are or what the ceiling looks like or is made of but I think you always want your vapour barrier. The breathing for your roof comes from your soffit vents and roof vents, not the air from your conditioned space. The risk is moisture/mold on your cold side sheathing .
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Went both directions r23 between the bottom cord of the trusses then r30 going the other direction.Damn! R53 I didn’t even know rockwool made anything that big that must of weighed a ton your building is gonna be super efficent I bet I used r 30 in my ceiling and r23 in the walls
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OP
Soccer918843
Well-known member
I’m in northern ny on the Canadian border my ceiling is 2x8 attic truss with tin going on the inside ceiling tin roof with it sheathed as well
banjopete
Well-known member
Take a look at this, based on what you have said for a description of the space yes you should be using a vapor barrier behind your ceiling sheathing. There are lots of good resources for this stuff around this is just one spot.
https://www.jlconline.com/how-to/insulation/q-a-ceiling-vapor-barrier-yes-or-no_o
You could also call your local building permit people and ask about local requirements.
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https://www.jlconline.com/how-to/insulation/q-a-ceiling-vapor-barrier-yes-or-no_o
You could also call your local building permit people and ask about local requirements.
Sent from my SM-G960W using The Garage Journal mobile app
Take a look at this, based on what you have said for a description of the space yes you should be using a vapor barrier behind your ceiling sheathing. There are lots of good resources for this stuff around this is just one spot.
https://www.jlconline.com/how-to/insulation/q-a-ceiling-vapor-barrier-yes-or-no_o
You could also call your local building permit people and ask about local requirements.
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Plastic should only be used in very cold climates when lots of insulation is used --- Plastic is a class 1 VB. In the lower 48 it must be used with caution.
Building have to breath -- in that that have to dry from both sides (inside/outside) Breathing is not leaking ... leaking brings water with it if there is water in the air.
Fiberglass will not stop air movement -- it needs the Vapor retarder.