Mold in the Bathroom

My co-op bathroom is windowless and has no vents, and the shower ceiling is constantly growing mold, even though we leave the door open after showers to let the steam out. We’ve tried everything from bleaching the ceiling several times, to using specialty products like KILZ. The mold always comes back. I think the ceiling is cement, and it may not be possible to install ventilation. Is there another solution? — Nadia Rensor, Mt. Kisco

Mold spores are always present in the atmosphere, and all they need to thrive is a high moisture level and a welcoming surface. So your mold problem won’t be solved until you solve the damp problem, even if you clean your shower ceiling until you turn blue (which, if you’re inhaling chlorine bleach fumes in an unvented room, won’t take long).

Ventilation to the outside is the real remedy. But Eric Messer, the president of Sunrise Building & Remodeling in Briarcliff Manor (, says installing a vent through concrete is “an adventure, at best. It’s hard to do. Concrete has steel rebar in it, and then it’s a question of structural integrity.” Adding a vent in an exterior wall can be an expensive proposition, too, he says. Current Westchester building codes require either a window or a vent in a bathroom, so if your coop is relatively new, the board may be responsible for solving the problem, especially since mold is a health hazard.

If that won’t fly, or if you’re in an older building that predates the code, the simplest option, says Messer, is to ventilate the bathroom to the rest of the apartment. “Get a small, wall-mounted fan to move air out of the bathroom after you shower. Install it on a timer, so it can run for a while if you go out. Even a small, 6-inch, plug-in fan that you leave on with the door open would help.”

Messer wonders if the fact that the mold grows only on the shower ceiling means you have a shower door with a transom above it. “Even if they leave the shower door open, the humidity hanging in the ceiling never dries out,” he says. “An operable transom that opens would allow the moisture to dry.”

A small dehumidifier would help, too. There are dozens of models, mostly inexpensive. Look for one that’s quiet and suited to the size of your bathroom. 

Other simple steps:

1. Take short showers to keep condensation to a minimum.

2. Use a squeegee to remove the moisture from the shower walls and ceiling after showering. Hang up your towels and bathmat so they dry faster. 

3. When your shower ceiling is completely dry and free of mold, paint it with a stain-killing primer and a mildew-resistant, anti-microbial paint. Sherwin-Williams, Benjamin Moore and Pratt & Lambert all offer versions. In general, latex paints are less hospitable to mold than alkyds, which act as food.

4. If you see mold growing again, skip the corrosive bleach and zap it using full strength white vinegar, or a solution of 1 cup of borax in a gallon of water. Both can be sprayed on and left to dry, which kills any spores lurking in crevices, and neither emit toxic fumes  (although the vinegar smells a little ... vinegary at first). Tea-tree oil is also an effective natural fungicide. Use about a teaspoon per cup of water, spray and leave it on. It has strong smell, but it fades.

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