Vapor Barrier on Basement Walls

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WorldExplorer44
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Vapor Barrier on Basement Walls

Post by WorldExplorer44 » Thu Jan 10, 2019 10:19 am

I have an unfinished 1200sq ft basement that is partially below grade. I live in Pennsylvania.

Always been humid in the space but never had any leaks or anything like that through the walls however I used drylock over all the walls just to be sure.

Watching Shannon's video (https://www.youtube.com/watch?v=zDNyjR1SHUQ) I installed rigid foam of 1/2 inch over the concrete block walls. I then installed 2x4 treated lumber framing. Foamed up all the corners and cracks etc. Everything went up smooth.

Now I am on to the batts insulation. This is where I think I might have messed up.

I bought R-13 FACED batts. Just as a test I filled one space with a roll and left it sit for 2 days. Note that I did NOT staple the facing. After 2 days there was a good amount of moisture behind the batts.

Will this moisture be solved by a vapor barrier? Or is there something I need to redo.

Thanks for any and all advice.


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Shannon
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Re: Vapor Barrier on Basement Walls

Post by Shannon » Thu Jan 10, 2019 11:43 am

What is the humidity level in your basement?
During the construction stage it would be common to have some moisture problems until everything is sealed up but if you have excessive moisture it will need to be controlled anyways.
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WorldExplorer44
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Re: Vapor Barrier on Basement Walls

Post by WorldExplorer44 » Thu Jan 10, 2019 2:04 pm

I have two dehumidifiers running 24/7 and it's able to maintain about 55-65%.

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Shannon
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Re: Vapor Barrier on Basement Walls

Post by Shannon » Fri Jan 11, 2019 8:01 am

Hmm that is a fair amount of humidity then. Is this normal for Pennsylvania? What you are keeping it maintained at is even on the high side IMO. I would say 40-50 is best depending on time of year.
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WorldExplorer44
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Re: Vapor Barrier on Basement Walls

Post by WorldExplorer44 » Sun Jan 13, 2019 10:28 pm

I can't say for sure about Pennsylvania in general but pretty much everyone I know that has a basement will have a dehumidifier running. My situation is made worse (I believe) because I have radient floor heat, except in the basement. So there is no forced air like most folks drying out the air in the house.

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Re: Vapor Barrier on Basement Walls

Post by Shannon » Sun Jan 13, 2019 11:04 pm

Here in Saskatchewan finishing basements in winter will usually have moisture in the wall cavities to some extent. But installing the foam reduces the amount because you are really getting rid of the cold concrete surface where warm moist air will turn to condensation.
In your case the 1/2” foam is maybe not enough to make a difference? I use no less then 1” when I do basements. Maybe running a extra dehumidifier during construction would help? We also do not use craft paper as a vapour barrier.
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WorldExplorer44
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Re: Vapor Barrier on Basement Walls

Post by WorldExplorer44 » Mon Jan 14, 2019 9:26 am

I did buy a new dehumidifier since my first post last week and that has helped.

Should I use a vapor barrier? Is it OK to use the faced batts with the vapor barrier over top of that?

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Re: Vapor Barrier on Basement Walls

Post by Shannon » Mon Jan 14, 2019 12:46 pm

Use one or the other ,not both. I’m not sure what is “normal “ in your area for sure . Check with the local lumber suppliers or contractors.
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