Cracked shower grout or silicone: how urgent is it really?

Not every crack in the shower is an emergency — but in a space that's wet every single day, the ones that matter can turn into a much bigger job if they're left alone. The difference comes down to whether water is just sitting on the surface, or getting behind the tiles.

How to tell if it's just cosmetic

• Check for movement, not just the crack: A thin, stable hairline crack in grout that hasn't changed in months is usually low risk if everything around it stays dry.
• Press gently around the area after a shower: If the wall or floor feels soft, or you see any dampness spreading beyond the crack itself, water is already getting through.
• Look at the corners first: Silicone at internal corners moves the most and fails first — it's normal for this to need resealing every few years, unlike grout on a flat wall.

Signs it's more serious

• Discolouration or a musty smell nearby: This usually means water has reached the waterproofing membrane or the timber behind the tiles.
• A soft or spongy feel in the floor near the shower: A strong sign the subfloor is already absorbing moisture.
• The crack keeps coming back after you reseal it: Repeated failure in the same spot often points to movement in the structure underneath, not just worn-out silicone.

Why it's worth acting early

• The waterproof membrane is the real barrier, not the tiles: Tiles and grout are the finish — the membrane underneath is what actually stops water. Once that fails, tiles looking fine on the surface doesn't mean much.
• A resealing job is cheap; a failed membrane repair is not: Catching this while it's still a surface crack is a fraction of the cost of fixing rotted subfloor or wall framing later.

What Paul recommends

If it's a stable, dry hairline crack, keep an eye on it and reseal when it starts to look worn. If there's any dampness, smell, or softness nearby, don't just reseal over it — Paul offers a free on-site inspection to check whether the membrane underneath is still doing its job.