Most problems with tile floors have to do with stained or cracked grout or cracked and broken tiles. Though grout is tough, when left unsealed it is quite porous and will stain. If applied improperly, it will crack and, when that happens, tile will eventually work loose. Tile usually cracks or breaks either because something is dropped on it or because the surface that supports it moves.

Movement is generally caused by normal house settling, earthquakes, or a supporting subfloor that isn't strong enough to handle the floor loads without deflecting. Of course, deflection doesn't occur when tile is laid on a concrete slab, but many wood subfloors should be reinforced with an extra layer of plywood subflooring prior to tiling.

Because liquids and foods can stain more porous tiles, they should be treated with sealers that resist moisture. Be aware, though, that the sealers can change the natural look of stone or unglazed tile.

Cracked tile can only be replaced, not repaired, so put some extras aside if you are installing a new floor.

Follow manufacturer's recommendations for cleaning glazed and unglazed ceramic and stone tiles and their grout. Wipe up any spilled food or liquid promptly because porous surfaces--especially the grout--will stain easily.