Sealing concrete before floating a floor in the shop?

[Cameron Handyside]

All,

I searched everything in SMC about shop floors before posting these question. I'm getting close to completion on my dream shop and plan to float a 3/4" ply floor on PT 2x4 sleepers over the concrete slab. I have a couple questions:

1. Should I seal or paint the concrete before installing the floor?
2. If so, is a simple one-part sealant good enough?
3. It's a fresh slab (aged ~ 6 months); do I have to etch it first?
4. I plan to install a 6mil vapor barrier, should it go on top or below the 2x4 sleepers.

thanks!
-Cam

[George Bregar]

Cameron, I'm sure you will get many responses but I thought it might make sense to look at an alternative to the 2x4 sleepers and do what I did. I used a product called Delta-FL which is a vapor barrier over concrete. No 2/4's required. Here is a thread on it.

http://www.sawmillcreek.org/showthre...light=delta-fl

[Jim Matthews]

I used OrVX, instead. It's a subfloor and insulation all in one.

They're 2x2 squares, tongue and groove.
OSB on top, Polystyrene on the bottom.

No vapor barrier needed, and they can be cut to fit with a circular saw.
(Although there will be styrofoam everywhere.)

[Jim Finn]

It may depend on where you are. I did not treat my floor before covering with 2by's and plywood but I am in a desert and have no ground water issues.

[Doug McClentic]

If you want to go with the sleepers I would put down the vapor barrier between the plywood and the sleepers. Be sure to use pressure treated stock for the sleepers to keep them from rotting due to moisture vapor condencing on the cooler concrete. Use insulation board between the sleepers. You should end up with a great long lasting floor. Also, I would attach the sleepers to the slab. This will make things go alot easier. Trying to secure plywood to 2x's that are not flat and keep moving around will be a big pain in the butt. There is really no need to seal the concrete unless you have major ground water issues. If you do sealing the concrete will not help. You would need to run an under slab drain with sump. I hope that is not the case.