I have a ranch style house with a concrete slab foundation. I'm want to put in either hardwood or engineered floors in the living room, hallway and 3 bedrooms. I need to use concrete leveler . What mil thickness vapor barrier if any would I need. I'm wanting to install either hardwood which i think is out of the question (nothing to nail it to) or engineered flooring. Would I have to glue the flooring down? Are engineered floors able to float after they are installed?
First off, get a moisture meter and get a reading off your slabs. Read in various locations but not near the furnace as it will always show dry. Since you said you need to use a leveler realize that you are putting moisture back into the concrete and it may take weeks for it to wick out. You'll need to take moisture meter readings after the leveler has dried.
A LVT click lock floor would be your best choice;something that floats over the floor, doesn't require adhesive and isn't affected by moisture. I wouldn't go less than a 4mm in thickness as it seems you have level issue with the floor and that thickness will handle it best. Get one with either an AO finish or a ceramic bead finish for scratch resistance. If you can find one with a Unilin locking system it tends to hold better than others. They make these in wood and stone looks.
Thank you both for your responses.