Hardwood over green concrete??

[OneSilverTruck]

My company is in the process of building a new house for a client. The house will be an elevated slab on grade with a CMU stemwall. The customer wants a 7" white oak plank floor. We will be installing a vapor barrier, then 3/4" CDX underneath the flooring.

I am finding mixed info about the concrete moisture content. We are in NW Fl and our wood floors are generally 10-13 percent moisture content. Do I need to wait until the slab reaches that moisture content, or how do I know when the slab is ready to be covered?

Thanks again,

[davenorthup]

Calcium chloride test tells you the MC of the concrete. In short; yes you need to let the slab cure; despite the "vapor barrier" and 3/4" ply. How will you fasten the ply?

Search the JLC archives for 2 articles on installing Hardwood over concrete.

[OneSilverTruck]

The plywood would be shot with nails, or offset spikes.

[James Eggert]

Does anyone use the dimple board in Florida? Air space and ply in one application. Most installers use tapcons to secure, cut nails and/or hilti shot could be used for placement until you finish securing the underlayment.

[Lavrans]

Curious if anyone is letting the plywood float. Seems you could use 3/4" battens to keep it up off the floor, and those would work to connect the ply together at seams.

Or just use strips of plywood (rather than full sheets), or 5/4 or 2x...