The short answer
How Water Reaches the Subfloor
Tile itself is waterproof, but the grout lines between tiles are not. Over time, grout can crack or crumble, especially in a climate with hot summers and spring storms. Water from spills, leaks, or flooding can then slip through those gaps and travel down to the layer beneath.
Once water gets below the tile, it soaks into the cement board, plywood, or wood subfloor. That trapped moisture has nowhere to evaporate, so the material stays wet. Over weeks or months, the wood can soften, warp, and eventually rot. The tile may still look fine on top, hiding the problem underneath.
- Cracked or missing grout lets water through
- Loose tiles create gaps at the edges
- Standing water from leaks or floods seeps downward
- High humidity slows drying of trapped moisture
- Subfloor wood stays damp and begins to decay
Signs of Water Damage Under Tile
You might notice tiles that sound hollow when you tap them. That often means the adhesive underneath has softened or the subfloor has started to break down. A musty odor in the room can also point to moisture and rot that you cannot see.
Look for discolored grout, dark spots near baseboards, or tiles that feel slightly spongy underfoot. If you have had a leak or a flood recently, pay close attention to these clues. Catching the problem early gives you more options for a simple repair instead of a full replacement.
What Happens If Rot Sets In
Rot in the subfloor weakens the entire floor structure. The wood can lose its strength, causing tiles to crack or shift. In serious cases, the floor may sag or become unsafe to walk on. The rot can also spread to nearby walls, joists, or framing.
Once rot is present, simply drying the surface is not enough. The damaged wood usually needs to be removed and replaced. That means taking up the affected tiles, cutting out the rotted subfloor, and installing new material before putting tile back down. The longer you wait, the more extensive the repair tends to be.
What to Do Right Away
If you suspect water is under your tile, start by stopping the source. Turn off the water supply if a pipe is leaking, or mop up any standing liquid. Remove rugs and furniture from the area so the floor can air out. Running a fan or dehumidifier helps dry the surface, though it may not reach deep moisture.
Then call local water damage pros to inspect the situation. They can check for hidden moisture and determine whether the subfloor is still sound. If you live in Rockwall, having a professional assess the damage early can save you from a larger repair later. The pros will usually need to remove some tiles to see what is underneath.
- Stop the water source right away
- Dry the surface with fans or a dehumidifier
- Move furniture and rugs off the wet area
- Take photos of visible damage for your records
- Contact a water damage professional for an inspection
Repair Options for Water-Damaged Tile
If the subfloor is still solid and only the grout is damaged, you may be able to regrout and reseal the tile. That can stop future water from getting through. But if the wood is already soft or rotted, the affected tiles must come up and the subfloor replaced.
The repair process usually involves removing the damaged tile, cutting out the rotted subfloor, and installing new plywood or cement board. Then the area is retiled and regrouted. In some cases, the new tile may not match the old, so you might need to replace a larger section for consistency. A professional can guide you through the options based on what they find.
Water damage does not wait
Phones are answered 24/7 for Rockwall and nearby communities.
Call Now (469) 698-4610Frequently asked questions
How can I tell if water is under my tile without pulling it up?
Tap the tile with a coin or a small hammer. A hollow sound suggests a gap underneath. Also check for cracked grout, a musty smell, or discoloration. A moisture meter, which a professional can use, gives a more definite answer.
Will a leaky pipe under the tile cause rot?
Yes, a slow leak from a pipe beneath the tile can saturate the subfloor over time. The wood stays wet and can rot. You might notice a higher water bill, warm spots on the floor, or the sound of running water. Fix the leak quickly and have the area dried and inspected.
Can I just reseal the grout to keep water out?
Resealing grout can help prevent future water intrusion if the grout is in good condition. But if the subfloor is already wet or rotted, sealing the top will not fix the problem underneath. The moisture needs to be removed and any damaged wood replaced first.