I'm planning to install an engineered wood floor. I plan to staple it to plywood over a slab. What is the preferred and alternative ways to anchor the plywood to the slab? Is 5/8" CDX plywood or OSB okay to use? Should the plywood be tonque and groove as well? Do I install a 6 mil poly over the slab then plywood then 6 mil poly then wood floor?

1. Powder actuated nails / tapcon screws or Urithane glue directly to slab.

2. for on slab go with CDX 5/8 is the minimum and will work with no problem. You just have to use more fasteners to keep it down. It likes to flex more than ¾

3. No you do not need T&G plywood use standard plywood with a ¼ space between all side of the boards.

4. If you nail or screw use 6 mill poly under the plywood and 15 weight felt paper on top of the plywood.


5. If you glue with a urethane adhesive you will be fine as long as your slab is dry (gluing plywood is the same as gluing down engineered). If it is not dry you will have to use MVP or some other chemical vapor barrier. Then use 15 wt felt paper on top of the plywood as well. If you plan to glue the plywood it would be cheaper to purchase engineered wood and glue it directly to the slab. The price of glue combined with the price of plywood makes it an expensive route to take.

One more question - How hard is it to get the powder actuated nails or tapcon screws into the slab and what length should I use?

Don't forget to acclimate the plywood!!

What's the use of a moisture barrier, if your going to poke holes all in it, compromising its purpose???

Why a wood subfloor, if your going to do engineered? Why not direct glue it to the concrete as it was designed to be installed?

You still need to flatten the concrete before you install a plywood subfloor.

Never heard of that one - but will do.

I questioned that one also but BR111 said do it.


The wood is bowed and BR111 said it can't be floated or glued - Your comments here welcomed on this one.

I'm working on that - bought the portland cement patch per your recommendation elsewhere.

Comments and help are welcome.

What cause their product to bow so much, it can't be installed according to thier recommended installation types? Sounds like a defective return!!

If you can nail it, you can glue it.