I need a new concrete subfloor due to water damage. Then 2x4s on top of that, then oak hardwood on top of that.

I am told by the concrete guy the 2x4s can do down the next day. The floor guy says it takes a month for the concrete to cure before the 2x4s can be done. Is either one of these right? How long does it take?

Thanks for the help.

1 Answer 1


if you are going to lay hardwood on to the subfloor, then i assume its going to be nailed down and not floating. if this is the case, then the floor has to not only be flat, but also strongly attached to the concrete below (to prevent deflection over time from moisture changes in the oak and in the subfloor). therefore, you would want the concrete to be hard, but not necessarily fully cured, before you start anchoring your 2x4's. assuming you will use construction adhesive and concrete screws (tapcons or something similar), you will want a low moisture content as well. since tapcons need a compressive strength of about 20MPa to work properly (a little less if its a smaller diameter), and since it takes about 7-10 days for new concrete to hit that as a minimum, i wouuldn't be anchoring anything until about 2 weeks later. if you go to soon, your anchors will strip out more easily and your adhesive won't bond well due to the moisture in the slab.

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