Can moisture from the sand and aggregate under a slab cause rising damp?
I want to do a similar job raising a floor by 1 foot 2 inches to the level of an existing kitchen floor. The floor to be levelled is a concrete slab floor and in good condition. My plan was to lay four inches of aggregate /crushed rock topped with 2 inches of sand with a sheet of plastic layed on top of the sand. On top of the sand I intend to put 4 inches of insulation foam with a radon barrier (plastic sheet) between the foam and the final finished 4 inches concrete slab. The question is: Due to the fact that the heavily moistured sand and aggregate is sandwiched between the slab floor and the 4 inch insulation will they both dry out and can the moisture from the sand and aggregate cause rising damp on the concrete block walls?