Plastic Sheeting Blog. Click on Home for all our product categories...

Vapor Barrier On Top Of Concrete, Below Carpet

Posted by Nana Hinsley on Tue, Mar 01, 2011 @ 10:27

QUESTION: We are looking for a product that can be laid on a concrete slab to act as a vapor barrier between the concrete and the carpet we plan to put in our basement.

Do you have a product that might work for this? 

Do you know if there are any contra-indications to putting the vapor barrier on TOP of the concrete to separate it from the carpet pad. It seems your products are used mostly between the ground and the concrete slab.

ANSWER: Any of our Vapor Barrier types of products can be used in this application over the concrete slab. I would recommend Raven Industries VaporBlock 20 Plus or the VaporBlock Plus 6 as two of the better ones, since they also block out radon, methane, and VOC's. Ideally, the liner should be sealed to the concrete floor using tape, or non-hardening polyurethane caulking, as close to the outside walls as possible. The idea is to help direct any moisture that flows along the plane under the concrete to the outside walls, so it can dissipate to the outdoors if possible. If this is not possible, and any moisture will be going into interior walls, they may want to stop a couple of inches short of the walls to keep from directing moisture up into the interiors of walls. I give the VaporBlock 20 Plus my highest recommendation, even though it is more costly. I believe it is such a superior product over all the others, that it is worth the difference. For this application, I would probably make the VaporBlock 6 Plus my next highest, even though it is pretty thin. It still has the very tight cell structure, and could be doubled it if you wish. Crawlspace 1800 is also a good choice.

Tags: Crawlspace 1800, vapor barrier on top of concrete