Roxul over closed cell spray foam basement

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Posted by: from Ottawa
11/9/2015 at 8:21:02 AM

Good day all,

I live in eastern Ontario. Quick question, I am planning on finishing my basement. First removing bath insulation from builder, framing 2'' from wall, add 2'' of closed cell spray foam then Roxul. Any issues with this setup ? do I have to add vapor barrier before drywall?

Thanks in advance

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Matthew from Matt of All Trades in Kitchener
Date/Time11/9/2015 at 5:09:35 PM

I would do one or the other. If you spray foam, get the proper thickness to avoid vapor barrier 2"min, but 3" of foam gets the R value for below grade walls...

Or, use just batts and vapor barrier.

I try and use spray foam as the cost is a bit of a wash with the batts and all the labor to put it all in vs. just foaming.

The framing only needs to be an inch off the wall. Enough space to get the foam behind the lumber to have a thermal break.

Hope this helps.

Matt Rogers

Matt of All Trades Inc.

Kitchener, Ont

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Date/Time11/9/2015 at 11:42:29 PM

Fill the cavity with 4" of closed cell no vapour no roxsul you'll be good to go and toasty warm.

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Date/Time11/10/2015 at 7:43:20 AM

There are no issues with this set up as the 2" closed cell is your vapour barrier, so no need to add a layer of super 6 poly.

Once you spray foam, you can install as much insulation as you feel necessary.

Keep in mind, the insulation doesn't keep you warm, it separates the two air temperatures from penetrating in/out. It is just as important to combine your insulation with proper supply & return air in order to ensure a comfortable environment both in the winter & summer months.

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