Roxul Insulation Questions....


Old 12-22-15, 10:22 AM
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Join Date: Dec 2015
Location: USA
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Roxul Insulation Questions....

I live in Maryland where we get hot summers and pretty cold winters. I am finishing the basement in our townhouse and wanting to use Roxul for all the things it is good for but my question is for vapor barrier. Do I need one with Roxul?
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Old 12-22-15, 10:27 AM
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Nope. No vapor barrier below ground level with any insulation.

Hang tight and I'm sure Bud will be along with a Building Science link.
Old 12-22-15, 10:34 AM
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Location: USA
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The front of the basement is below ground but the backside is ground level and has a walk out.
Old 12-22-15, 12:37 PM
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Location: VA
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Anything below grade should not have a VB. Also everything below grade should have an air gap between the inside and outside wall.
Old 12-22-15, 12:58 PM
Join Date: Mar 2005
Location: USA
Posts: 6,126
Keep in mind that the inside of a basement does not know what the current outside temperature is. Usually, the soil at 4' deep averages about the same as the annual average temperature. Because of the lateral heat transmission of basement wall construction materials, the interior wall temperatures vary little with depth. - It has very little to do with the mythical "frost depth" that applies only to the structural design of the footings for "frost heaving".

Air gaps do some good as long as they are not continuous to the point where there is circulation and is no "dead air". They do minimize heat transmission/loss due to direct conduction.


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