Can Tile Floors Be Damaged by Water Underneath?

Tile is waterproof, but the grout lines between tiles are porous and can absorb water. Over time, grout can crack or crumble, creating pathways for moisture to seep through. Water can also enter through gaps at the edges of the floor, where it meets walls or fixtures, or through cracks in the tiles themselves.

Once water gets underneath, it spreads across the thin-set adhesive and the subfloor below. The subfloor, often made of plywood or cement board, can absorb moisture and start to swell or rot. This hidden moisture can go unnoticed for a long time, especially if the surface of the tile looks dry.

Water under tile can cause the adhesive to break down, leading to tiles that pop up or become uneven. The subfloor can suffer the most damage, as plywood can swell, warp, or rot when exposed to moisture for extended periods. This can compromise the structural integrity of your floor.

Mold and mildew can also develop in the damp environment under the tile, which can be a health concern. If the water source is contaminated, such as from a sewer backup or flood, the risk increases. In severe cases, you may need to remove the tile and subfloor entirely to address the damage.

You should call the pros if you see signs of water damage under your tile, especially if the water came from a contaminated source. They have the tools to dry the area thoroughly and can identify all affected materials. Attempting to handle it yourself might leave moisture behind, leading to mold or structural issues later.

The pros will typically remove the affected tile and subfloor if necessary, then dry the space completely. They can also inspect for mold growth and address it safely. The cost of professional help depends on the extent of the damage, the materials involved, and how long the water has been present.