My house is 58 years old. I bought it in 2000 and the house was carpeted throughout except kitchen and bathrooms. 3 years ago I removed all carpeting and put laminate flooring with moisture bariers. The carpet showed no signs of moisture. 8 weeks ago the laminate flooring started warping in one room and when we removed the flooring in two rooms the moisture bariers were wet. We removed all the laminate flooring from the house and found the slab to consistently read 15.5 moiture reading using a digital moisture meter that shows 8.0 as maximum acceptable reading. What can we do to be able to put flooring down. Leak detection experts and plumbers have ruled out any plumbing, appliance and drainage leakage. Since the slab has been left uncovered for 8 weeks there is no moisture on the slab and is dry to the touch but still reads high on meter. I taped pieces of 2'x3' clear plastic on all rooms with duct tape to seal completely and left for 96 hours. When I removed the plastic sheets they were dry, no moisture on the plastic. I want to lay porcelein tile on all floors but do not know if it will stay secure. How can I moisture proof the slab to prevent loosening of the tile?
