# Basement Blanket insulation Framing



## coyotethrust

Hello,

After much consideration, I decided to leave my white blanket insulation up in my basement, and frame in front of it. Now, I have put drywall up in one room, and took the advice from this video:






Basically, it says that if you keep the blanket wrap up, you simply fill the new stud wall with an unfaced insulation. 

I am a bit paranoid now, and was wondering what the folks of this great forum think? Will everything be ok if I continue on with Roxul? Here is a pic of the wall I am working on now:


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## Nealtw

You are good as long as you don't have two vapour barriers.


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## coyotethrust

Nealtw said:


> You are good as long as you don't have two vapour barriers.


Thanks Neal! How do you feel about basement ceiling insulation - do or don't?


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## Nealtw

coyotethrust said:


> Thanks Neal! How do you feel about basement ceiling insulation - do or don't?


If you are going after sound, sure but use resilient channels too
Make sure pot lights are rated for insulation.


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## Bud9051

Doesn't seem fair for you to ask us for the OK on an approach that depends a lot on how the foundation was built and is performing. I checked your other posts and didn't see any prior basement discussion.

The plastic covered blanket insulation (I assume covered on both sides) will act as a vapor barrier and eliminate any drying to the inside. The result will be the inside surface of the foundation and the outside surface of the white plastic will slowly accumulate moisture until it matches the moisture in the ground outside.

Here is a link that discusses the issues related tot the diaper insulation, photo #3.
https://buildingscience.com/documents/digests/bsd-103-understanding-basements?full_view=1

Bud


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## coyotethrust

Bud9051 said:


> Doesn't seem fair for you to ask us for the OK on an approach that depends a lot on how the foundation was built and is performing. I checked your other posts and didn't see any prior basement discussion.
> 
> The plastic covered blanket insulation (I assume covered on both sides) will act as a vapor barrier and eliminate any drying to the inside. The result will be the inside surface of the foundation and the outside surface of the white plastic will slowly accumulate moisture until it matches the moisture in the ground outside.
> 
> Here is a link that discusses the issues related tot the diaper insulation, photo #3.
> https://buildingscience.com/documents/digests/bsd-103-understanding-basements?full_view=1
> 
> Bud



Hi Bud,

To elaborate, my foundation walls are poured, with a waterproofing membrane on the outside. There is also drain tile running back to the sump along the perimeter. The insulation wrap is only faced with the plastic, not covered on both sides. 

Thanks for the link.


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## Bud9051

Let me apologize up front and disclose, I HATE BASEMENTS. 
I'll try to be short.
The exterior membrane is good, but moisture comes in both liquid and vapor forms and the vapor passes right through concrete, vertically as well as horizontally. For a dry basement that membrane would run down the wall, under the footing, and connect to a similar material under the slab. Almost never done so moisture vapor can still migrate up behind that insulation and accumulate.

Moisture can also come from the air inside the basement if that air finds a way past the plastic and reached the cold foundation.

The guidance provided in that link and others are not a guarantee that you will have problems, just that the risks are slightly higher than their preferred approach with rigid foam against the foundation.

Your nose will probably tell you if a problem develops, the old basement smell. Very few finished basements avoid that end, thus my dislike for them.

 Best,
Bud


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## Nealtw

Bud< if there is a problem it will show up in the first few months. With more insulation it is less likely to wick moisture and with drywall, there is less of a chance of warm moist air getting to the concrete. I would sooner see what we do here. Works fine but it is closer to this than foam. We build a wall just like this and insulate that and add a vapour barrier leaving a space between insulation and concrete. 
Foam boards usually will not work on a concrete wall inside because it is not smooth like a block wall so the choice would be sprayed foam. No system will protect against a leak.


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## coyotethrust

So if I want save money, is it ok to go with unfaced fiberglass? Or should I stick with Roxul? Thanks!


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