Add the plywood layer on top and anchor it to the concrete with 15 concrete screws predrilled and countersunk per 4 x 8 ft.
Vapor barrier over concrete slab carpet.
If your concrete passes the moisture test then plastic sheeting at least 6 mils thick will prevent moisture from getting into your laminate flooring.
It needs to dry and then stay dryto avoid flooring problems.
Many moisture problems associated with interior concrete floors and slabs on grade can be minimized or eliminated by installing a vapor barrier under the concrete.
Install a plastic vapor barrier.
A concrete vapor barrier is any material that prevents moisture from entering a concrete slab.
Vapor barriers have been associated with certain concrete slab on grade problems including curling and cracking.
But they have also proven to be beneficial in reducing failures of moisture sensitive flooring materials adhesives and coatings caused by excessive emission of moisture vapor from concrete slabs.
Dimpled polyethylene underlayment is available from home centers flooring suppliers or online.
They look similar to carpet padding but they have a plastic film on the surface to block moisture.
Before rolling out the underlayment be sure to sweep vacuum and remove all debris on the substructure.
Concrete absorbs and retains water and the moisture can seep into the carpet padding and then into the carpet.
Any of our vapor barrier types of products can be used in this application over the concrete slab.
Lay the sheet over the concrete floor dimples down overlap adjacent edges and tape the seams.
A concrete vapor barrier is simply a sheet of polyethylene plastic visqueen placed directly on top of the sub grade before the concrete floor or slab is poured to help keep moisture from the soil from passing up through the concrete.
Install it over a layer of fill.
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.
How to install vapor barrier on concrete floor under laminate flooring always read the flooring manufacturers recommendations and instructions before installing the underlayment.
Fill in any.
Where plastic sheets must be joined overlap the sheets by several inches and use strong vinyl tape to secure them.
It seems your products are used mostly between the ground and the concrete slab.
Start with a vapor retarder with a perm rating that reflects the needs of the space.
Inspect it before pouring the concrete and fix any tears it may have.