Can the tiler just re-grout the corner?

No. It will crack again. The corner needs a flexible joint; that is the one-line fix on the report.

Is flexible grout enough?

Better than cement grout, but a proper silicone movement joint at every internal corner is what the tiling standards ask for.

Why does grout crack at internal corners?

Because cement grout barely stretches and the two planes that meet at a corner move differently, a stud wall against blockwork, a timber floor that deflects against a wall that does not, two walls drying at different rates in the first year. Internal corners should be a flexible silicone joint, not grout. It is a snag on a dry wall and a potential leak at a shower or bath, where the crack is a path for water.

Updated 2026-09-19Punch List AI 1.2 · iPhone and iPad

An item screen with the classification card, findings and recommendation

Step by step

Photograph the corner along its length and one close-up of the crack; tap the tiles beside it for hollowness.
Note whether it is a wet area, that sets the severity.
Record: 'Cement grout cracked in the internal corner, full height; corner should be a silicone movement joint.'
Action: rake out to full depth, clean and dry, seal with matching sanitary silicone; re-bed any hollow tiles first.
Severity: low on a dry wall, medium in a wet area, high if the tiles are hollow or there is staining below.

Why does grout crack at internal corners?

Step by step

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Why does grout crack at internal corners?

Step by step

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