What Are Signs of Water Damage Under a Slab?

Look for discoloration or dark stains on your floor coverings, which can appear even without a visible spill. Carpet may feel damp, and vinyl or laminate flooring might show bubbling or warping. On walls, watch for cracks that travel upward from the floor, as shifting from a wet slab can cause them.

Tiles can become loose, and grout lines may darken or crumble. Hardwood floors might cup or buckle, with planks lifting at the edges. These visual signs often start in one area but can spread. If you see these changes, it is wise to investigate the moisture source promptly.

Water erodes the soil supporting a slab, which can lead to settlement. This causes new cracks in the concrete slab itself or in interior drywall, especially around door frames and windows. Doors and windows may also start sticking or become difficult to open and close properly as the frame shifts.

Monitor your water meter and utility bills. An unexplained, consistent increase in water usage often points to a hidden leak. To check, turn off all water fixtures in your home and see if the meter's leak indicator is still moving. This simple test can confirm a problem.

Fixing water damage under a slab often requires accessing the leaking pipe. This might mean tunneling under the slab or creating a small access point through it. Sometimes, pros recommend rerouting plumbing lines through walls or ceilings as a less invasive alternative, depending on the home's layout.

After fixing the leak, the area beneath the slab must be dried. This may involve specialized equipment to extract moisture and dry the sub-slab fill. The final step is repairing any damage to your flooring and walls. Policies vary, and your insurer decides what is covered, so review your policy early.