Using grout in inside corners—such as where a wall meets a floor or where two walls meet in a shower—is a common installation mistake. Because buildings naturally expand, contract, and settle over time, the surfaces meeting at these corners move slightly. Grout is a rigid, cement-based product that has zero flexibility; when the corner shifts, the grout has nowhere to go but to crack. These cracks not only look unsightly but can also provide a path for water to seep behind the tile, potentially causing damage to the substrate. Caulk, specifically 100% silicone or color-matched sanded/unsanded caulk, is designed to be elastomeric. This means it can stretch and compress as the building moves, maintaining a watertight seal without cracking. Using a high-quality caulk in all plane changes is an industry standard for professional tile installations. If you currently have grout in your corners that is cracking, it is recommended to remove the cracked grout and replace it with a flexible caulk that matches your grout color to prevent further water issues. In wet areas, ensure the caulk is mold-resistant.
Key considerations
- caulk vs grout corners
- why use caulk in corners
- is grout in corners bad
- silicone caulk
- grout color match
- waterproofing