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So Confused! Conflicting Information Regarding Underlayment

1K views 4 replies 4 participants last post by  janehoya 
#1 · (Edited)
Hello,

We are installing a floating laminate floor over cement. Cottage was built pre-1980 and doesn't have a vapor barrier. Cement is 4" above grade.

Our contractor wants me to use Dream Home Quietwalk underlayment from Lumber Liquidators. Instructions (confirmed with the manufacturer) state that the vapor barrier should face up rather than down and in contact with the concrete. This makes no sense based on what I've read and the opinion I received from another contractor (vapor barrier should be on the bottom). Lumber Liquidator told me to install a 6 mil. vapor barrier on concrete and then install the Quietwalk per its instructions, but I am worried moisture will just get trapped between the two vapor barriers.

I am inclined to install a 6 mil. vapor barrier directly on the concrete and then install either 3 mil or 6 mil squares of cork as the underlayment for the floating laminate floor.

I've been driving myself mad trying to figure out the right thing to do and would greatly appreciate any opinions.

Thank you.

P.S. My contractor says that I am over-thinking this.
 
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#2 ·
Go by what Liquidators recommended. Can't see how vapour could get between layers that are compressed together. But, double check to see if thr foam surface is supposed to be against the laminate to prevent movement. Remember ..the moisture comes up through the concrete. Should also install dehumidifier in basement. unless it is air conditioned, to prevent excess humidity from warping the laminate. Personally. I wouldn't use laminate in basement due to the excess moisture. You can get vinyl that looks like laminate. Also, check out DRI CORE products and installation guidelines to get a comparison of practices.
 
#5 ·
Thanks very much for your response. You are correct, we are installing above grade.

I toyed with the idea of putting the 6 mil. vapor barrier down and then the quietwalk product on top, but a couple of people warned against it. Said that the moisture would just get trapped between the top and bottom barrier and create lots of issues.

Thanks again.
 
#4 ·
I also would never have install a laminite on a slab that close to grade. Been there done that and had to replace it all after a few years. And yes I used below grade rated laminite.

Most laminites I've installed all stated to tape all the seams in the padding, and glue all the seams when installing over concrete.
For any warrenty on the flooring to hold water I'd be consulting the install manual from the company that made the flooring, not just guessing. Not following there directions to the letter will void the warrenty.
 
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