Basement framing on R20 insulation

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Posted by: from Milton
11/1/2015 at 11:09:40 PM

In order to support R20 insulation in my basement, should I only use 2x6 studs since R20 insulation materials has 5 1/2" thickness? I'm thinking of just using 2x4 as I'm fighting for space but unsure if this is allowed.

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Date/Time11/2/2015 at 9:50:34 AM

Hi Ted,

If you frame with 2 X 4s, do it an inch away from the wall and use spray foam. That will give you more than r20 and be really tight which is just as important.

Good luck with it.

Jim Kuzma

Kettleby Handyman

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Date/Time11/2/2015 at 10:32:26 AM


You don't want to compress the insulation. This is why R 20 should go with 2x6 construction. If you were to put it into 2x4 walls, you are defeating the purpose. Either go with 2x6 or lower the R value to accomodate the wall thickness.

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Ted in Milton
Date/Time11/2/2015 at 10:46:21 AM

Appreciate the reply. It makes sense to use 2x6 frame to support R20. So for the rest of the interior walls, 2x4 should be fine then.

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Date/Time11/8/2015 at 8:21:00 PM

Hi Ted,

You need to have 2x6 and don't use spray foam insulation there is lot of concerns if in enclosed area produces fumes and story is it can case a cancer.


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Ted in Milton
Date/Time11/11/2015 at 9:27:09 AM

What about blanket insulation with R 20 which is 1 inch thick then 2 x 3 frame on top?

Is the order of installation - Tyvek (reversed) on concrete wall first, then blanket insulation before framing? No space needed in between Tyvek and blanket insulation?

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