So here's my problem...

I have a slab that is reading 18 on the moisture meter. The slab is about six months old. We need to raise the hit of the floor to meet up with the adjoining room. We were planning on nailing down 3/4" plywood with visqueen and felt before we found out about this moisture problem.

Once we nail into that concrete, we're just asking for more moisture problems. So then I assumed we would glue it down. I was thinking we would apply moisture sealer, then glue the plywood down and then glue the wood. The wood by the way is a Terra Bella product which I'm sure you all know has a thin top layer. Bostic's however, says to put the moisture sealer on top of the plywood after its been glued down but who wants wet plywood?

What about vinyl for the concrete then nailing the plywood before gluing the wood on top?

Please give me your opinion or recommend a adhesive manufacturer that can give me some kind of warranty for this type of installation.

Thanks.

I recently used this sika wood adhesive. I am very impressed. The also have a moisture control primer for cement floors. I use a Tramex concrete moisture encounter meter. This is one many manufacturers specify, other than the calcium chloride tests. The meter you are using is not giving readings that make sense to me. I would be surprised if your situation would not be a candidate for this system. Though, to be sure I would obtain the Tramex meter.

I would use the primer then glue the plywood to the concrete. No reason to full spread the plywood use the tubes.

www.sikaconstruction.com/con/con-wfb.htm

What concrete meter reads 18%?????

Are you using a wood meter to test the concrete???????????

The Calcium Chloride Tests are being done now and will be completed on Sunday. I'm not sure the name of the moisture tester since I'm not the one who did it but I confirmed it was a concrete on.

I've been given suggestions with everything from the old school sheet vinyl to loose laying plywood and then setting the wood floor to that - almost as a floating floor system.

My Tramex Concrete Moisture encounter, meter, which is the only concrete meter recognized by wood manufacturers, only reads to 6%. A floor fails the test when the meter gets anywhere close to 4.5% on the upper scale.

All the manufacturers of those combination systems, sealer and urethane adhesive, warranty for wood flooring, not plywood. You'd think it would not matter. So I'm pretty sure you'll not get a warranty. Some warranty to bring the concrete down to an "acceptable" range ( 3lbs of MV in a 24 hour time span over 1000 ft. ). You'll need to contact each manufacturer individually to see what they say about your situation. Dri-Tack has a system, Franklin has one as does Bostik's and Sika. I think you're correct in your assumption that the concrete needs to be sealed, then the plywood glued down. Then the Terra Bella glued down as well. As for using vinyl, that is a tried and true system. However, you'll need to use a quality vinyl adhesive that will not break down with moisture. I've employed that way myself on numerous occasions. I'd lay the vinyl, then glue and nail the 3/4" plywood with Franklin Advantage. It's formulated to be used over vinyl. I hand nailed with 1.5" fluted masonry nails. Just enough to hold the plywood into the adhesive well. After 24 hour dry time, I'd overlay the plywood with felt and nail down my wood. NEVER had a problem. It is more expensive than a concrete sealer. The results of your CC tests will determine which way to go.

Now that is a custom "floating" floor.

If it were me, I'd go ahead with your SIKA sealer and two ply double 3/8" floating subfloor. But instead of using Aquabar between the 3/8" panels, I'd glue those panels together as well as using SHORT staples or screws. It will be hard to adhere two layers of 3/8" ply without using glue. In fact, I'd consider two layers of 1/2" instead, as it will lay flatter IMO. The SIKA sealer along with the polyethylene sheeting under the plywood should be more than adequate to reduce MC down to acceptable levels. Furthermore, you're having an engineered floor installed, which can withstand a higher MC and is more stable to boot. I'd be more concerned about the stability of your floating subfloor. Typically, most use floating plywood subfloors to install 3/4" solids over, which, when nailed with 1.5" fasteners, help hold the layers together and the weight of the wood helps hold the plywood flat. Since in your case, you're gluing a lighter weight material down, you will need a stiffer, heavier subfloor IF you want to float it. Personally, I'd consider shooting it down to the concrete. Once sealed and the plastic is installed, I doubt you're going to have a moisture problem. BTW, 8 lbs as measured by a CC test is not too terribly bad. The SIKA sealer should be able to handle that by itself. I've seen much higher readings. My concern is that after all this effort to ensure there is not a moisture problem, your floors will feel spongy underfoot from being installed on a floating subfloor. That won't be acceptable either, IMHO.