Dark Grout in the Shower

Grout goes dark in the splash zone, especially low, where water sits, and in corners the squeegee misses. It can be surface film. It can be grout that has worn porous and holds everything. It can be a stain that will not turn back to the original color no matter what you buy. You find out by cleaning a small square and by looking at whether the grout is still solid.

Pick a spot the size of your palm. Use one bathroom cleaner you trust, ventilate, do not mix it with anything else, and scrub that square. Rinse and let it dry. Compare. If it lightens to match grout that stays dry, you have a cleaning job and a drying job, not a demolition. If it barely changes, the color may be in the material. If the grout is sandy, cracked, or missing, cleaner will not replace it.

Drying is what keeps a cleaned square from going dark in a week. Fan, tissue test, outdoor duct, 20 to 30 minutes after showers, curtain spread, water pushed off the floor of the shower. A shower that stays wet until noon will redo the grout by Friday. People call that "impossible grout." It is often an idle fan.

Recoloring or sealing grout is a later choice, after the area stays clean and dry long enough to be worth it. Sealing a damp, dirty joint locks the current situation in. Regrouting a shower is a real project. It is fair when the grout is failing, and it is wasted when the only problem was steam and a shut door. Let the palm-sized test and a week of real ventilation make that decision.

The caulk joints are not grout. Do not scrub a soft caulk line and expect it to behave like cement. Failed caulk comes out and gets replaced when the joint is dry, or a pro does it. Soft drywall or loose tile around the dark grout means stop scrubbing. Water behind the wall is a licensed pro's repair.

Bleach poured down the wall because a video started that way is how people gas themselves in a small room and stain what they touch. Stay with one labeled product, a brush, and air. Gloves if the label says so. Eyes and kids out of the spray.

If the darkness returns only along the bottom course, look for standing water. A clogged weep in a door, a liner that holds a pool, a slope that does not drain. Fix the pool and the grout has a chance.

Write the test result: lightened, or did not, solid or sandy. That sentence is the plan.

Live with the test square for seven showers before you buy a grout dye or call a tile person. The square is an experiment. If it stays light, clean the rest in the same boring way and keep the fan honest. If it darkens while the rest of the shower dries quickly, that patch may just be worn grout. If the whole shower darkens again, you are still leaving it wet.

Take the photo of the test square on day one and day seven in the same light, near a window if you can. Bathroom bulbs change the color and you will argue with yourself. The photo ends the argument. It also helps if you do hire someone, because they can see whether this is surface wear or a wall that needs more than a brush.

Do not seal the grout the same afternoon you clean it. Trapped moisture under a sealer is a cloudy mess. Let the shower go through a couple of dry cycles. Then decide if you even need sealer, or if the fan already did the lasting work.

Stuffy mornings that worry you belong with a doctor. Anything that means cutting drywall or working on gas equipment belongs with a licensed pro.

Grout, steam, and the fan are in the ClearNest picture guide When Your House Doesn't Feel Right. It is $2.99 at https://clearnestair.com/book.