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 wall coverings 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 wall covering.

Solution: Use paint or apply wall coverings 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. (An overflow pan is available for about $125 plus shipping from AMI, 800-929-9269.)

Problem #4

Water-resistant drywall used as a 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.

Problem #11

Yards that slope toward foundations invite water to enter basements and crawlspaces.

Solution: Regrade yard surrounding house so it slopes away at a rate of 1 in. per foot.

Problem #12

Improperly flashed or caulked windows (and those with large amounts of surface condensation) let moisture seep the surrounding wood, drywall and insulation.

Solution: Properly flash and caulk windows during installation; minimize condensation with good ventilation and airflow.

Problem #13

Leaky flashings and shingles allow rain to infiltrate and other areas that can trap moisture and are difficult to inspect.

Solution: Perform yearly roof inspections--even if you do it from the ground with binoculars.

Besides damaging your house, mold can cause severe health problems.

IT'S DOING THAT TO MY HEALTH?

One consultant we interviewed confessed he crawls around in moldy places day after day, month in and month out and never suffers ill effects. Others--some estimate about 10 percent of the population--are severely allergic to mold. It's primarily the dinky reproductive spores that people react to. Twenty of them sitting side by side could fit across the period at the end of this sentence. That means they're hard to filter out. The spores also have an incredible "hang time" (as my teenage son would say); they're able to stay suspended in midair for hours on end. That means they're easily inhaled.

With even slight exposure to molds and spores, sensitive people may experience headaches, runny noses, skin rashes, nausea, sinus problems, memory loss and coughs. They may feel listless for long periods of time. In short, they feel as though they have a perpetual case of the flu. Newborns, the elderly, the sick, and those with compromised immune systems can be affected severely, even fatally. Babies and toddlers, who love to crawl around on possibly moldy carpets and stick possibly moldy things in their mouths, also are highly vulnerable to mold-induced illnesses. Super-sensitive people often go to extremes to rid their houses of the materials that harbor the dirt and dust that molds feed on. They'll replace soft, textured materials with smooth, hard surfaces that are easier to keep clean and less likely to trap debris and moisture. Out go the carpets and draperies; in come hardwood floors and metal window blinds. Out go the cushy couches; in come the vinyl chairs.

Tightly sealed newer houses may be better at holding in heat, but they're also more likely to trap moisture and spores. Mechanical ventilation, like an air-to-air heat exchanger, is critical for healthy air quality in tightly sealed new homes.

In truth, most of us fall somewhere between the two extremes of invincibility and super sensitivity. But even "normal" folks will react to unusually high concentrations of mold and spores. And the time you're most likely to stir up spores and inhale and ingest them is the very time you're trying to get rid of the stuff. That's when you need to be the most careful.

DISPOSE OF IT CORRECTLY OR YOU'LL JUST MAKE MATTERS WORSE

Step one in getting rid of mold is to fix the moisture problem that's setting the stage for its growth. This is key! You can scrub, dispose of and replace moldy materials, but until you fix the problem, mold will keep returning. The fix can be as simple as sealing up leaky air-conditioning ducts (Fig. B) or as daunting as reshingling a leaky roof or regrading your yard so water runs away from, rather than toward, your foundation. Sewer backups and floods also set up ideal environments for mold and mildew growth.

Once the moisture problems are fixed, get rid of the moldy materials carefully. Rough handling of damaged materials will not only stir up spores and spread them even farther around your house but also launch zillions of spores into the air, where you'll inhale them. One square foot of moldy drywall can harbor more than 300 million mold spores; slamdunk that onto the basement floor and you're just opening another Pandora's box. Even dormant spores inhabiting dried-out materials are irritating to inhale, and if they find moist environs again, they can zip back to life and establish new colonies.

The smart way to get rid of moldy building materials

THE KEY TO REMOVING MOLDY MATERIALS is containment and thoroughness. Seal off the area. Create a crude "air lock" door to contain spores and dust by covering the opening with a sheet of poly slit in the center, and then cover that with another sheet or flap. Wear a respirator and work slowly and surely. Double-bag or wrap all materials, then wash all remaining hard surfaces with a 1/2 percent bleach solution and let dry.

* Wear a good cartridge-type respirator, available through a medical or safety equipment supplier. One good mask is a Willson triple-seal respirator (No. 03711; $30.75, plus shipping) with a P100 filter cartridge ($52 for a carton of 10) available from Direct Safety, (800) 528-7405. A simple dust or particulate mask doesn't offer adequate protection. Wear gloves and goggles if you're scraping.

* If your basement or main floor has flooded, get it as dry as possible within the first 72 hours, before mold and mildew can get established. Drill holes in drywall or remove lower sections of it to let the inner wall and insulation dry out.

* Close off any ventilation grilles with polyethylene sheeting and duct tape. Shut down your furnace so the blower doesn't spread spores and dust throughout the house.

* Remove everything--furniture, pictures, and lamps--from the room.