Ceramic tile assemblies  installed with portland cement setting materials when properly installed over concrete slabs are generally not adversely affected by the presence of moisture. This is a very popular topic especially if a delamination of the tile occurs. In cases of hollow and loose tile, people often want to blame excessive moisture from the slab as the cause of the failure. The root cause of tile failures are most often related to improper installation related to a lack of bond mortar coverage, improper selection of bond mortar, lack of movement joints, or a combination of the three.  

Excessive moisture in ceramic tile assemblies over concrete slabs often will result in the presence of efflorescence in the grout joints. Efflorescence is the accumulation of soluable salts brought up from the concrete slab by water travelling up from below. When the water evaporates, the salts are left in the grout joints and can be crystalline in appearance and off white in color. The salts can be cleaned off the surface with pH balanced cleansers. The source of water intrusion should be abated once it is noticed.

This very much differs when stone tile is used especially if the stone tile falls in the sedementary or metamorphic catagories such as marble, travertine, and limestone. These stones can and will suffer damage from excessive moisture from below. Often we see surface spalling caused by the same efflorescence creating surface pressure on the stone causing the surface to spall or flake.