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13moe
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# Posted: 30 Apr 2023 02:21pm
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Hey there, was looking to insulate my cabin 2x4 walls with Rockwool R14. I'm seeing that some people say that no vapour barrier is needed with it, and also that some say it is needed. Thoughts?
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Brettny
Member
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# Posted: 30 Apr 2023 02:46pm
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Its prety cheap. I would use it. Did you use house wrap?
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13moe
Member
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# Posted: 30 Apr 2023 02:50pm
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No house wrap
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Brettny
Member
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# Posted: 30 Apr 2023 05:50pm
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Why not? I would do both. Even if you have to wrap it around the studs. Both of them help to air seal the building and that can matter more than R value.
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ICC
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# Posted: 30 Apr 2023 06:05pm
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A vapor barrier is not required in all climate zones but an air barrier should be used everywhere.
Some people do say not to bother with a vapor barrier with rockwool because rockwool does not absorb moisture. True enough, but if moisture does condense inside the wall there may be wood studs to absorb moisture.
A vapor barrier can cause problems in a warm humid climate zone when the interior spaces are air conditioned (cooled). I would follow the climate zone recommendations in effect for the location
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Aklogcabin
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# Posted: 1 May 2023 10:01am
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Rockwool will not stop Vapor from moving into the walls and causing a mold problem on the wood. Studs n such
The northern areas where you have large temperature differences a vapor barrier is needed so moisture isn't dropped inside of the walls.
If you have a cold attic construction model then you will need a vapor barrier.
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travellerw
Member
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# Posted: 1 May 2023 09:29pm
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Where are you from? Here in Alberta vapor barrier is ALWAYS required (except spray foam). Barrier must be sealed around any penetrations (i.e. boxes, wires, pipes). It must also be sealed at the one open edge (usually bottom) with sealant.
The only exception is spray foam which is the barrier itself.
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ICC
Member
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# Posted: 1 May 2023 09:43pm
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Quoting: travellerw Where are you from?
Profile states Ontario.
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NorthRick
Member
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# Posted: 3 May 2023 05:31pm - Edited by: NorthRick
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Quoting: 13moe Hey there, was looking to insulate my cabin 2x4 walls with Rockwool R14. I'm seeing that some people say that no vapour barrier is needed with it, and also that some say it is needed. Thoughts?
If you are in Canada you need vapor barrier on the inside of the walls. Rockwool won't rot, but it won't stop moisture from passing through it. Warm moist air will go through the interior wall, through the rockwool, and when it hits the cold surface of the inside of the exterior wall it condenses into water, and if the surface is cold enough, it then freezes.
Now you have water inside your wall. Put up the polysheeting. It may not completely prevent this, but it reduces it to where it doesn't cause issues, primarily mold.
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Cedar Fever
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# Posted: 3 May 2023 07:27pm
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I am in the south. I used rock wool and pine birds for walls. No barrier, figured I would let it breath.
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