Combating mold and mildew in Your Home.
They could be damaging your home and your health.

What's wrong with a little mold and mildew? As long as they stay put behind the laundry tub, out of sight under the basement carpet, or only peek around the edge of the bathroom wallpaper, who cares? Well, YOU should, because they're not only eating away at your house, they could be eating away at your health, too.

Here we'll take a look at what mold and mildew are, how they affect the health of you and your house and, finally, how you can prevent their growth and get rid of the stuff.


Though there are thousands of different types of mold and mildew, they all have two things in common: The first is that their mission on Earth is to digest the organic world around them. The second is that they all need moisture so their little digestive enzymes can go to work.

There are differences between mold and mildew, but for our purposes, we can call the entire gang mold. Molds are neither plants nor animals. They're microscopic organisms containing enzymes (responsible for digesting and decomposing) and spores (in charge of reproduction). Mold dwells within the fungi kingdom: a realm includes mushrooms, yeast and other seemingly unsavory characters. But the truth is, these decay organisms aren't unsavory at all. Without them, toppled trees, dead animals and fallen vegetables wouldn't decompose. Our land would get piled higher and higher with dead stuff. We wouldn't have foods and medicines like cheese and penicillin. The problems arise when mold starts chomping away at things we don't want them to--affecting the look, smell and structural integrity of your house.


Mold needs to consume something to survive, and it's perfectly happy eating your house if you let it. Some molds and mildews are fond of the cellulose in the paper backing on drywall, insulation and wallpaper. Others have a ravenous appetite for the glues used to bond carpet to its backing. Left unchecked, mold eventually destroys the parts of the drywall, wallpaper and carpet it attacks. But many molds just like to feast on the everyday dust and dirt that gather in the perpetually moist regions of your house. They won't destroy your house, but they can sure make it look, feel and smell bad. Mold can mar your walls with white spider web-like growths or clusters of small black specks. It creates the smell we often refer to as "musty." It can be slippery and dangerous when it grows on damp basement stairs. Molds rarely go so far as to rot wood or do structural damage--they'll leave that to their fungal cousins--but they can wreak plenty of havoc. We can't overemphasize that mold needs moisture to get established, grow and reproduce. Mold problems and longstanding moisture or high humidity conditions go hand in hand. To conquer mold, you must also conquer moisture problems. Table below shows common hangouts for mold and some steps you can take to minimize its growth and the damage it inflicts.

13 common breeding grounds for mold and mildew

Problem #1
Leaky air-conditioning duct joints, especially those running through a hot attic, create a moist environment for mildew.

Solution: Seal all duct joints with the special flexible mastic available heating and cooling supply stores.

Problem #2
In warm environments, impermeable vinyl wallcoverings can trap moisture-laden air as it moves from the warm exterior to the cooler interior. Mold degrades the drywall and adhesive behind the vinyl wallcovering.

Solution: Use paint or apply wallcoverings with permeable paper backings that don't trap moisture on exterior walls.

Problem #3
When washing machines in a room without a floor drain overflow or hose connections burst, water with no point of exit will soak into adjacent carpet, drywall and insulation.

Solution: Always provide a floor drain near the washing machine. Install an overflow pan directly under the machine or install a 1-in. lip at the doorway to contain overflows in main-level or second-story laundry rooms.

Problem #4
Water-resistant drywall used as a the backer quickly degrades once subjected to moisture.

Solution: Install cement backer board, which will remain structurally sound even if repeatedly subjected to moisture.

Problem #5
Poorly ventilated bathrooms allow surface mold to grow.

Solution: Install a bathroom fan (or at least, open a window) to exhaust moisture. Remove surface mildew by scrubbing the area with a 1/2 percent bleach solution. When the area is dry, prime it with an alcohol-based, white pigmented shellac, such as Zinsser Bullseye, and use a paint containing mildewcide.

Problem #6
Poorly constructed crawlspaces promote mildew growth. Bare earth floors transmit huge amounts of moisture.

Solution: There are many regional differences and solutions. Cover bare earth with 6-mil poly sheeting. Heat, cool and humidify the area the same as the rest of the house.

Problem #7
Freshly cut firewood stored indoors emits huge amounts of moisture.

Solution: Store it outside.

Problem #8
Humidifiers (especially reservoir-type central units and portable units) provide both a growth medium and a distribution system for mold and mildew.

Solution: Clean and treat the reservoir often with an antimicrobial solution, available at most hardware stores.

Problem #9
The condensation pan directly under the coil of your central air conditioner can harbor mold.

Solution: Before each cooling season, clean the pan with a 1/2 percent bleach solution and make sure the continuous drain is working.

Problem #10
Finished concrete basements that haven't been thoroughly waterproofed from the outside are problematic. When moisture migrates through the earth and non-waterproofed concrete walls, it can get trapped behind vapor barriers, carpet, layers of insulation and drywall.