Adding vapor barrier to ceiling after sheet rock

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stripe14631
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Adding vapor barrier to ceiling after sheet rock

Post by stripe14631 » Mon Nov 26, 2018 9:28 pm

I just bought a house in norther Minnesota. The garage walls are insulated with unfaced batt insulation without a vapor barrier and the attic has no insulation or vapor barrier. Both walls and ceiling are sheet rocked. I just finished installing a 90% high efficiency down draft furnace and would like to finish Insulating the attic with blow in insulation. My question is what are my options for installing a vapor barrier after the ceiling is in. I thought about getting 1/4 in fan fold foam board and cutting it to size and spray foaming or caulking where it meets the joist. The problem with that is the product is not rated as a vapor barrier. what other options are there other than taking down all the sheet rock and putting up poly???


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Shannon
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Re: Adding vapor barrier to ceiling after sheet rock

Post by Shannon » Mon Nov 26, 2018 10:05 pm

Well you are correct the fan fold would not effectively do what you want.
I have not looked for any lately but there should be paint or primer products that can do a good job of sealing your walls and ceiling. There are many homes and garages that do not have a “proper air/vapour barrier and without a major drywall re do paints and primers are your only real option in most cases.
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stripe14631
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Re: Adding vapor barrier to ceiling after sheet rock

Post by stripe14631 » Wed Nov 28, 2018 11:14 am

Thanks shannon for your quick reply. Mud and tapping is not my forte so I was trying to avoid it. Do you think putting down strips of poly and sealing it to the joists with caulk or great stuff spray foam would be effective or a waste of time? And how important is a vapor retardant in a attached garage. Thanks again for what you do. Because of your channel I was able to reside my entire house and replace windows and know it was done right.

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Shannon
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Re: Adding vapor barrier to ceiling after sheet rock

Post by Shannon » Wed Nov 28, 2018 6:25 pm

I would just use the paint solution and go with that. It is still important to stop vapour transfer but the attic will dry easier anyways if there is proper ventilation . The walls are the ones that will not dry as easy but just look for the paint and go that route.
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KevP
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Re: Adding vapor barrier to ceiling after sheet rock

Post by KevP » Thu Nov 29, 2018 3:35 pm

Hey,
Is the garage heated? I recently fixed my garage due to framing rot. I talked to Shannon and guys here and decided to go with my original thought of Rockwool. I pulled a permit. Here is what the inspector suggested. Garages get wet mostly. You don't want to make an air tight space in there. You want the walls to breath. They almost suggest no vapor barrier on ceilings to let the ceiling to dry up in case of moisture or leaks. So my garage is unheated. The inspector told me to skip the vapor barrier. As Shannon said if you have a heated space, your best bet is to go the paint route. Just do multiple coates since you need a certain layer depth to acheive the level you like. Not as good as the plastic but letting old houses breathe is better especially in a garage

KevP
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Location: Saint Paul, MN USA

Re: Adding vapor barrier to ceiling after sheet rock

Post by KevP » Thu Nov 29, 2018 5:10 pm

Fyi im in St Paul. Not as cold as the northern MN but still colder than other places

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