How to Remove Mold

Here's how to identify a mold problem and remove the mold.

By Bruce Clark

From The Family Handyman

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About This Project

Mold is a major-league nuisance. It blackens the grout lines in your shower, discolors drywall, shows up as black spots on siding, darkens decks, and grows on and rots damp wood everywhere. Even worse, it can be bad for your health. It releases microscopic spores that cause allergic reactions, runny noses and sneezing, as well as irritating, even injurious, odors.

Almost every home gets mold infestations. The trick is to stop them before they get big and harm both you and your home. In this article, we’ll show you how to identify mold and eliminate the small infestations as well as the big ones that have gotten out of hand.

You can easily remove minor mold with ordinary household cleaning products. But disturbing big infestations can be bad for your health, particularly if you are an allergy sufferer or have a weakened immune system. When you discover an extensive mold problem, we recommend that you use the rigorous protective measures we show in Photos 1 – 6, or consider calling in a professional to handle the problem. (Look under “Industrial Hygiene Consultants” or “Environmental and Ecological Consultants” in your Yellow Pages. Or call your local public health department.) And even if you hire pros, read through this article and make sure they follow similar precautions to keep the mold from spreading throughout your house.

How to Identify Mold
Mold is everywhere. It’s a type of fungus that grows from tiny spores that float in the air. It can grow almost anywhere that spores land and find moisture and a comfortable temperature, between 40 and 100 degrees F. Typically that includes about every damp place in your home.

You can easily spot the most visible type of mold, called mildew, which begins as tiny, usually black spots but often grows into larger colonies. It’s the black stuff you see in the grout lines in your shower, on damp walls, and outdoors on the surfaces of deck boards and painted siding, especially in damp and shady areas. A mildewed surface is often difficult to distinguish from a dirty one. To test for mildew, simply dab a few drops of household bleach on the blackened area. If it lightens after one to two minutes, you have mildew. If the area remains dark, you probably have dirt.

Tips for Mold Prevention
The key to stopping most mold is to control dampness. The worst infestations usually occur in damp crawlspaces, in attics and walls where water has leaked in from the outside, and in basements with poor foundation drainage. Stopping leaks, ensuring good ventilation in attics, keeping crawlspaces dry and routing water away from the foundation are the best defenses.

Mildewcide in paint is usually effective for controlling surface mold in damp rooms like bathrooms and outside in shady areas. Many paints already have mildewcide in them. Check with your paint dealer to be sure. You can add mildewcide, although you might void the paint warranty.

Mildew is a surface type of mold that won’t damage your home’s structure. But other types of mold cause rot. Probe the suspect area with a screwdriver or other sharp tool (Photo 3). If the wood is soft or crumbles, the fungi have taken hold and rot has begun.

If you have a high concentration of mold, you may smell it. If you detect the typical musty odor, check for mold on damp carpets, damp walls, damp crawlspaces and wet wood under your floors, wet roof sheathing and other damp areas. Clean up these infestations right away before they get worse.

CAUTION: A FEW TYPES OF MOLD ARE HIGHLY TOXIC. IF YOU HAVE AN ALLERGIC REACTION TO MOLD OR A HEAVY INFESTATION INSIDE YOUR HOME, CALL IN A PRO TO ANALYZE THE TYPES. OR CALL YOUR LOCAL PUBLIC HEALTH DEPARTMENT AND ASK FOR MOLD-TESTING ADVICE.