I am desperate for advice! We have a 30 year old home on a concrete slab. Several months ago we did a complete remodel of our kitchen and installed new 20x20 porcelain tiles. After about a month we began to notice the grout had dark spots in areas. After extensive investigation including running a camera through our plumbing lines to rule out any leaks, we pulled up some of the tiles and discovered water under the tiles! The thin set was attached to the slab, but the tiles popped right off. The flooring company, their product representatives, and the installer said all industry recommendations/guidelines were followed with installation and the problem has to be with excessive moisture coming from the slab. They did calcium chloride tests and said our moisture level was 4 times the level recommended for flooring. They wanted to put down a moisture barrier and reinstall the tile. We previously had ceramic tile and had no problems with moist. We have wood floors in all other areas of our home and have no problems. An independent home inspector came in and told us we had moisture but not enough to hurt the wood floors. He advised AGAINST putting a moisture barrier down in the kitchen as the moisture is still present and has to escape so we would run a risk of the water moving into the walls or the other areas of our home and ruining the wood floors!! He recommended we use natural stone sealed with a water based sealer and not sealing the grout. The floor company disagrees saying we will still have problems with mildew and "salt" buildup on the grout. The floor company will not recommend any type of flooring unless we put a moisture barrier. HELP!!!!! What happens in other homes with moisture in the slab when they put down a barrier before laying tile??? Surely we are not the only house in the country with this issue. Does it travel up walls and cause mold? Should I put down porcelain without a barrier thus going against the floor company advice? They strongly advice against porcelain in this situation as it doesn't "breath". They "think" maybe a red clay ceramic tile without sealing the grout and not putting a barrier "might" be ok. I am soooooo confused and upset. Can anyone offer advice?