Dark Stuff Where the Tub Meets the Tile

That joint is the wettest inch in a lot of bathrooms. Water runs off the wall, sits on the tub edge, and creeps into whatever caulk is tired. The dark line looks like a cleaning failure. Sometimes it is. Sometimes the caulk has opened and the wall behind it has been taking splash for months. You need to know which before you buy a stronger bottle.

Dry the room and look. Continuous caulk with a surface film can be cleaned: one product, air, no mixing, then a real dry. Caulk that is split, loose, or gummy needs replacement after the joint is dry, not a coat of new caulk on top. If you press the wall and it gives, or tile is loose, or paint is bubbling above the joint, stop. That is water in the wall. A licensed pro should open what needs opening. Scrubbing the surface of a soft wall spreads debris and does not dry the cavity.

The habits that soak this joint are simple. A curtain or door that dumps water onto the edge. No squeegee, so sheets of water run down after every shower. A fan that does not run, so the joint never gets a dry period. Fix those and a sound joint can stay boring. Ignore them and a fresh bead fails on the same schedule as the old one.

Under the tub, if you can see an access panel or a ceiling below, look for staining after you have noticed a bad joint. A stain below means the splash is not staying in the bathroom. Photo it. That picture is for a plumber or a carpenter, not for a caulk coupon.

When a joint is sound and merely grimy, clean it and change the water habit, then reassess in a week. When it is failed and the wall is firm, recaulk on a dry day or hire the bead, and do not use the shower until the product says you can. When the wall is soft, make the call and skip the shopping.

Do not pry tile off to "see how bad it is" if you are not ready to rebuild what you break. Looking is pressing gently and photographing. Opening is a project.

Kids' splash and a handheld sprayer aimed at the joint will reopen a story you just finished. Aim the spray at bodies and at the tub, not at a tired seam, until the seam is new and the fan is real.

Write firm or soft, film or split. Three words. They pick the next person, even if that person is you with a tube of caulk on a dry Saturday.

If you are going to recaulk a firm joint yourself, pull the old material out instead of burying it. A dry joint, a bead that actually sticks to both sides, and a day without shower splash will outperform a thick cosmetic smear. If that sentence already sounds like more than you want to do, it is a short hire. There is no prize for a crooked bead you have to live with.

Use the fan during the cure time the product asks for, and keep steam out of a fresh joint. People recaulk at night and shower in the morning because the bathroom is the only one. If that is your house, plan the work around a day you can wash elsewhere. A joint that gets soaked while it is curing is the same joint you started with.

Look under the edge with a flashlight after a shower once the work is done. You want water in the tub, not a glisten along the floor or a drip in any access below. One dry check is worth more than admiring the color of the new caulk.

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

The tub joint is a picture in When Your House Doesn't Feel Right from ClearNest. $2.99 at https://clearnestair.com/book.