Originally Posted by Servant_
I'm helping my in-laws with unglued tongue in groove laminate flooring. there is a minimun 3/8 to 5/8 inch space required. The sheetrock doesn't reach the floorand the gap is large enough for the flooring to fit under. Will it cause a problem to have a larger space by going in front of the sheetrock. We don't want the flooring to shift.
Also it says to seal the cement and then put down a vapor barrier, is the sealant a must?
Regarding sealing the cement, as Handy Mac said, it's advisable but I don't think it's completely necessary pending on what the cement is like in its current state. Concrete needs to be cured for about 2 months. If your concrete is older then that then you can do a simple test.
Tape down a 3x3 piece of polyethylene (thick plastic) to the concrete for 48 hours. If moisture beads form or the concrete darkens you may have a moisture problem.
Pending on the severity of the moisture problem you can seal the concrete, then apply a vapor barrier and moisture blocking underlay (a minimum of 2mm thick) over the concrete. Most situations only require the vapor barrier (which is thick plastic) and the underlay. Its also a good idea prior to purchasing your laminate, to test its water absorbency. Check this by soaking a piece of the laminate in water for 6 hours. If swelling occurs to the extent that the laminate is separating, choose a higher quality laminate.