How do I keep a new bathroom from getting moldy?

Control the moisture, because mold follows water

You keep a new bathroom from molding by keeping it from staying wet. The EPA's summary is that the key to mold control is moisture control.^[1] That comes down to three things: a fan that really vents the shower steam outdoors, house humidity that stays moderate, and any water leak dried or fixed fast. Most of it is built in during the remodel and kept up with habits afterward.

Get the ventilation right in the remodel

If you are still planning the work, ask for a bathroom ventilation fan with humidistat or timer vented to exterior, which is how Virginia Cooperative Extension lists the feature for a moisture-resistant new home.^[3] Put those words in the written scope and ask the contractor where the duct ends. A fan ducted into the attic or ceiling space only moves the steam. Extension also advises avoiding pocket doors in humid areas such as bathrooms,^[3] a small detail for a bath being redesigned.

Fan work involves wiring and a duct through the ceiling or wall, so it belongs with licensed trades, and some bathroom work needs a permit. See whether you need a permit to remodel a bathroom in Virginia. Waterproofing behind tile and around the valve and drain is also the remodeler's job to do and to show you; what is done and when is covered in what happens during a bathroom remodel.

Daily habits that matter

The EPA's advice is short: run the bathroom fan or open the window when showering.^[1] A timer or humidistat makes that automatic. Leaving the fan running for a while after the shower lets the room dry rather than just clear.

Humidity matters house-wide. The EPA suggests that, if possible, you keep indoor humidity below 60 percent (ideally between 30 and 50 percent) relative humidity.^[1] A small humidity meter from a hardware store tells you where you stand. If you see condensation or moisture collecting on windows, walls or pipes, the EPA says to act quickly to dry the wet surface and reduce the moisture source, because condensation can be a sign of high humidity.^[1] The EPA adds: Use air conditioners and/or de-humidifiers when needed.^[1]

Between showers, let towels and mats dry rather than piling up damp on the floor, and wipe standing water off a glass door or tub rim if it tends to sit.

Dry leaks and spills quickly

When water leaks or spills occur indoors, act quickly. If wet or damp materials or areas are dried 24-48 hours after a leak or spill happens, in most cases mold will not grow.^[1] A drip under a vanity, a wet spot on the ceiling below a shower or a loose caulk line deserves attention the same week. Fix plumbing leaks and other water problems as soon as possible,^[1] and hire a licensed plumber when the fix means opening the plumbing.

Clean small patches the right way

Places that are often damp are hard to keep entirely free of mold. For hard surfaces, the EPA says to scrub mold off hard surfaces with detergent and water, and dry completely.^[1] Do not paint or caulk moldy surfaces, since paint applied over moldy surfaces is likely to peel.^[1] If the moldy area is less than about 10 square feet (less than roughly a 3 ft. by 3 ft. patch), in most cases, you can handle the job yourself.^[2]

When to call a licensed pro

Bring in a Virginia-licensed contractor if the fan is undersized or vents into the attic, if you see a leak or soft spot, or if mold returns after cleaning. For mold that smells but cannot be seen, the EPA suggests hiring an experienced professional.^[1] See why a new bathroom gets moldy for the usual causes.

Virginia's Board for Contractors says: "If the work you are considering is valued at $1,000 or more, a valid Virginia Contractor’s License is required for the license category in which the contractor is to work."^[4] Check the licence number and class on the DPOR licence lookup before you sign.

Find help

Browse more remodeling answers or remodeling contractors in Virginia. When you are ready, describe the bathroom work once and licensed local contractors can quote it, fan and waterproofing included.