Should I put caulk over missing grout in shower corners?
Shower corners and changes of plane require flexible silicone caulk rather than rigid grout, which inevitably cracks and crumbles when walls shift. Applying caulk over crumbling debris without proper clearance prevents a watertight seal, causing water to pool in unplaned corners and behind damaged joints.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1chip out the old stuff and add a new waterproof silicone bead
- 2Caulking directly over the damaged grout area
- 3Cutting out remaining old grout with an oscillating multi-tool, cleaning and killing mold, patching with fresh grout, and allowing it to cure before caulking
- 4using a higher pH degreaser
- 5using a hydrogen peroxide based cleaner
- 6using white vinegar
- 7Using regular shower spray, dish soap, bleach, electric scrubbers, and specialized grout cleaners weekly.
In their words
Unedited, most upvoted first, each linked to the thread it came from.
“I was replacing the caulk on this tub and what I guess is grout behind the caulk broke off. Should I just caulk over it?”source ↗
“Hi all! The shower grout is grey, but looks like soap scum (I think?) that has built up. What can I use to clean it to restore it back to the grey?”source ↗
“I rent my apartment so I am not sure what kind of grout or tile this is, but it is IMPOSSIBLE to get clean.”source ↗
“I feel like I have tried everything I know - regular shower spray, dish soap, bleach, electric scrubbers, grout cleaner, etc. and I clean the shower at least once a week!”source ↗
“The tile itself doesn’t really stain but the grout constantly is discolored and even has a pinkish tone to it.”source ↗
“It is embarrassing with guests because it consistently looks dirty even though I clean it regularly!”source ↗
“Poor shower remodel by previous owners. For one this back corner holds water because it wasn't planed correctly.”source ↗
“They didn't use silicone here and the grout is cracking. Same for another corner.”source ↗
“What should I use to cover this Crack in my fiberglass shower?”source ↗
“So it does or does not need new grout first? I’l only assuming it is grout it’s something that chipped out while removing the caulk.”source ↗