Why You Should Not Grout Corners in Tile Installations

Why grout corners is discouraged

If you're wondering why don't you grout corners, the short answer is that interior corners experience more movement and moisture exposure than flat joints. Grout is rigid and does not easily absorb expansion or contraction from temperature changes, settling, or substrate movement, which increases the risk of cracks, chipped edges, and moisture seeping behind tiles. According to Grout Maintenance, proper corner treatment is a key factor in long-lasting tile installations. In many setups, professionals reserve the inside corners for a flexible sealant rather than cementitious grout to allow movement while keeping moisture out. In showers and tub surrounds, this detail is especially critical because water exposure is constant. The goal is to create a transition that can move with the wall rather than a rigid block that can fail under stress.

When grout corners might still be used

There are rare cases where a tile layout may tolerate corner grout, such as in very dry, non-wet spaces with minimal movement or where expansion joints are planned elsewhere in the structure. Some installers choose to grout edges near corners if the joints are large and the surface is structurally rigid, but this should be a deliberate decision backed by substrate testing and movement planning. If you do decide to grout the corner, pair it with a proper movement joint elsewhere and ensure high quality cement grout with low shrinkage. For wet zones, however, most professionals recommend sealing the inside corner with a flexible sealant to prevent moisture buildup and cracking. The Grout Maintenance team notes that even small misalignments or wall flex can create stress that grout cannot accommodate.

Alternatives to grouting corners

The most common alternative is to seal interior corners with a flexible silicone or polyurethane caulk. A color-matched silicone bead can blend with tile while remaining pliant enough to absorb movement and resist mold growth when properly applied. In some installations, a single bead of sealant in the corner is all that’s needed, with cement grout running along the two wall edges. For very wet areas, choose a high-quality sanitary silicone that remains flexible and resists mildew. If you prefer a grout-like appearance, you can use a flexible grout system that includes a sealing component, but many tile pros still favor dedicated caulk for corners to preserve long-term performance.

Planning tile layout to prevent corner stress

Effective corner management starts at layout and substrate preparation. Leave intentional gaps for movement where walls meet, and design with expansion joints at logical locations rather than forcing a rigid edge into a corner. Use a quality thinset adhesive compatible with both your tile and the substrate, and verify that substrates are flat, plumb, and free of excessive flex. Running grout lines to the corner can be visually appealing, but only if you have verified that the corner will not experience significant movement or moisture exposure. When in doubt, consult a tile professional and reference Grout Maintenance guidelines for best practices in corner detailing.

Step by step for corners in wet areas

1. Prepare the joint by cleaning and drying the corner thoroughly. 2) Decide if a flexible sealant is required based on moisture exposure. 3) Apply a backer rod if necessary to maintain proper depth for sealant. 4) Run a continuous bead of silicone or polyurethane caulk along the inside corner. 5) Tool the bead for a clean, tight finish. 6) Allow the sealant to cure fully before exposing the area to moisture. 7) Grout the remaining flat joints as usual, ensuring proper curing and sealing where needed. Following these steps helps prevent water intrusion and stress cracking in corners.

Cleaning, maintenance and long term care

Corners sealed with silicone require different maintenance than grout lines. Regular cleaning with non-abrasive cleaners, avoiding harsh solvents that can degrade silicone, will extend sealant life. Inspect corners for sealant degradation, cracking, or mold, and re-seal when needed. Use a grout guide to maintain color consistency across joints, but remember that any changes to the corner should prioritize movement absorption and moisture resistance. If you notice recurring leaks or cracks around corners, consult a professional promptly, as neglect can lead to more extensive tile or substrate damage.

Common mistakes to avoid

• Sealing with non-flexible products in a wet corner. - Forcing grout into a corner with visible movement. - Skipping substructure checks or expansion joint planning. - Neglecting proper curing and cleaning of sealants. - Using abrasive cleaners that degrade silicone. The right approach is to balance a rigid grout on flat joints with flexible sealants in interior corners and to plan the layout to minimize stress wherever possible.