Concrete Slab Glue Down Vapor Barrier?

[Mark]

I need some guidance from the group. I have an existing slab on grade and I'm hoping to install engineered wood flooring. Most likely glue down. I received some advice from an installer to glue down a vapor barrier underlayment first then glue the wood flooring to the vapor barrier. Sounded strange to me. He said there was flooring underlayment product intended for the job....but I have not found anything yet. Any suggestions? thanks Mark

[Bob Morrison]

There is a plywood underlayment available that has a built-in vapor barrier. I suspect that is the product the installer has in mind. You will most likely not find this product in a big box store, but will need to go to a "regular" lumber store.

[Muff]

Mark, there should be a vapor barrier under the slab, get a moisture meter and check the moisture content of the concrete. If cured properly and it has a vapor barrier under the slab you should be good to go and glue the engineered wood to the concrete. I had my new home done this way a year ago and have no problems. I'm in Tampa Florida. Muff

[John Reddy]

You don't need a moisture meter. Take a one foot square piece of polyethyne sheeting and duct tape it to the slab on all four sides. If there is moisture under it after 24 hours, you need a vapor barrier.

[Glenn]

I would suggest you do that after a prolonged wet spell.