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Lumber & Composites

Basement question: Do I need a barrier of some sort between the 2x4s and the concrete walls/floors?



I am finishing a 1700 square foot basement.  Do I need a vapor or moisture barrier for the walls and floors?  I understand it is best practice to use treated lumber for the plate on the bottom; however, I do not know anything about the necessity of barriers.


Thanks in advance for your responses.



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Posted 2013-04-13T04:14:08+0000  by LennartzBuilder LennartzBuilder

i would place vapor barrier on all of the exterior walls.  you do not need to have it on interior walls or floors or ceilings

Posted 2013-04-14T12:38:05+0000  by joshcameron

Hello LennartzBuilders,


If this is a newer home you should have - per code already a 6mill plastic under the concrete slab.

My suggestion would be to tape a piece of 2'x2' plastic sheeting to the concrete floor and place a lamp over it for about 24 hrs. If the moisture shows on the underside of it - side facing the concrete slab - than I would advise to install a vapor barrier sheeting before the 2x4s and floor go in place.


Do you need a vapor barrier on the walls depends on your geographical location.


Here's the map from the DOE  - that indicates the correct placement based on the location.

doe vapor barrier placement.jpg

Here up north we have vapor retardants installed on the inside of the envelope - on the outside we put house wrap which is a rain screen/AIR barrier.


Hope this helps and please do not hesitate to post back with any additional questions you may have.



Posted 2013-04-15T13:40:54+0000  by George_HD_CHI
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