Is the Concrete Slab is Ready for Flooring?

If you’ve got a concrete slab, you’re in luck.  In a best case scenario, concrete slabs provide a (relatively) glass-smooth surface for flooring and are so stable that you should never have squeaks. But one thing to keep in mind with installing flooring directly on concrete is that concrete has a lot of moisture…and it retains moisture for a long time.

Huge concrete projects retain moisture seemingly forever.  Hoover Dam supposedly is still drying out and cooling down from its pour over 75 years ago.

If the tape doesn’t hold down the plastic, then the concrete might be too dirty…or too moist even to hold down tape.

Back to the residential world, how do you know if the concrete slab is ready for flooring?  Moisture is your biggest culprit, so do these things:

• Well, first of all you’ve got to wait a good three or four days.  Concrete will not be dry before then.
• But after that 3-4 day waiting period, you can tape a square of clear plastic to the surface of the concrete.  The plastic doesn’t have to be very big–maybe two feet square.
• Now, tape down the entire perimeter of the plastic with duct tape.  Make sure it’s down good and tight.
• Wait 24 hours.
• If you come back and find fogging, beads of water,or any evidence of moisture on the inside part of the plastic, it’s not time to install flooring yet.  Wait a day, then tape down the plastic again.