Mold

What It Means

Mold is a fungus that grows indoors on damp materials, including porous ones such as ceiling tiles and carpet. The key to controlling it, according to the Environmental Protection Agency (EPA), is controlling moisture: clean up the mold and fix the leak or damp that fed it, or it will most likely come back. For small areas on hard surfaces, EPA's advice is to scrub with detergent and water and dry completely.

How It Sounds at Home

• "There's black stuff growing behind the washing machine."
• "The basement smells musty again."
• "Is that mold on the ceiling or just a stain?"

The Breakdown

How to clean a small area (EPA)

1. If anyone in the home has health concerns, talk to a health professional before you start.
2. Find and fix the water problem: the leak, the damp or the humidity feeding it.
3. Put on an N-95 respirator so you don't breathe in mold or spores, long gloves that reach the middle of your forearm, and goggles without ventilation holes.
4. Scrub mold off hard surfaces with detergent and water.
5. Dry the area completely.
6. Throw away porous materials such as ceiling tiles and carpet if they've gone moldy; mold can fill their gaps and pores.
7. Don't paint or caulkCaulkingSealing cracks and gaps between parts of a house that don't move, such as around window and door frames, with a flexible filler called caulk. See more over moldy surfaces. Clean and dry them first.

How big is too big. EPA says an area under about 1010,000 stepsA popular daily step goal that began as the name of a 1960s Japanese pedometer; later studies find health benefits begin well below it. See more square feet, roughly a 3 foot by 3 foot patch, can in most cases be handled yourself. If there's been a lot of water damage, or the mold covers more than 10 square feet, EPA points to its guide "Mold Remediation in Schools and Commercial Buildings".

Try it today. Look under the sinks and around the tub for anything damp, and dry it the same day; EPA says drying within 24 to 48 hours usually stops mold growing.

Good to Know

EPA says chemicals that kill mold, chlorine bleachChlorine bleachHousehold bleach made with sodium hypochlorite that whitens, removes stains and disinfects, but can fade colors and damage some fibers. See more included, aren't recommended as a routine part of cleanup; detergent and water on hard surfaces is its standard. If you do use bleach, never mix it with a cleaner containing ammonia, since EPA warns that makes toxic fumes. To stop mold starting, EPA advises drying wet materials within 24 to 48 hours of a leak or spill, and keeping indoor humidityIndoor humidity levelHow much moisture the air inside a home holds, given as relative humidity. EPA advises keeping it below 60%, ideally between 30% and 50%. See more below 60%, ideally 30% to 50%.

Related Terms and Categories

• Mildew

  A flat, usually gray or white mold that grows on damp surfaces such as shower grout, curtains and fabric left wet.

• Indoor humidity level

  How much moisture the air inside a home holds, given as relative humidity. EPA advises keeping it below 60%, ideally between 30% and 50%.

• Window condensation

  Water droplets that form on the inside of window glass when moist indoor air meets the cold pane, which EPA treats as a sign of high humidity.

• Grout cleaning

  Scrubbing the lines of grout between tiles with a brush and cleaner to lift dirt, soap film and mildew stains.

• Frozen pipes

  Water pipes in which the water has turned to ice, blocking the flow and building pressure that can split the pipe and flood the house once it thaws.

• Homeowners insurance claim

  A request to your homeowners insurer to pay for damage or loss the policy covers, backed by photos, a list of what was lost and your receipts.

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