This Saturday we laid concrete in what used to be a garage, but was converted into a living room. I am confused on what to do next; I have been told to seal the concrete before applying plywood as subfloor. I would like the finish product to be laminate wood floor. And need advice to do this correctly.

 

I am confused as to how you are pouring concrete in an existing room. did you pour over an existing slab or did you remove and replace the existing slab?

Regardless, a vapor barrier below the slab is a good first step, if you did it. as for the new floor I would suggest installing the sheathing on sleepers. sleepers are 1x2 or 2x2 installed flatwise on the floor at 16" spaces which get the floor off the concrete so it doesn't feel like a concrete floor. if you are concerned with water thru the slab, you can use pressure treated sleepers.

if you do go pressure treated, make sure you use hot dip galvanized or stainless fasteners as the chemicals used in treating have changed and are much more corrosive to standard fasteners.

 

Always, always, always use treated lumber for any framing that's in direct contact with cement. Interior or exterior work doesn't matter, always use treated next to concrete!!

Fresh concrete needs to cure for a certain period before it's sealed, post a thread in the Concrete & Masonry forum for more clarification on that. I sub-out all of my concrete work, so I'd differ to the pros in that field for their judgement on fresh cement work. On an existing slab, I'd paint it with drylock, or other water sealing product, then put down a felt paper barrier over the slab and then go with the sleepers like clardl suggested. And definitely follow the advice on fasteners given, it's absolutely critical with the new treated lumber products.