Sick House

Most new florida homebuyers are probably more concerned with hurricanes than any other climate-related problem-and that's understandable given the four named storms that slammed into the state in mid-2004. Homebuyers, however, should also be concerned about mold contamination, which can sicken a house and send Florida homeowners to the poor house.

Mold contamination is common in our hot, humid state. Lawsuits flood the courts, and insurance coverage for mold and mildew damage has dried up. To understand just how big of a problem it is, simply enter "mold mildew buildings" into your Web browser and brace yourself.

Insurance companies paid out more than $3 billion in mold-related claims in 2002, classifying mold and mildew damage as a disaster. Risks are so large that most insurers have limited their coverage of mold-and-mildew home damage to anywhere from $10,000 to nothing at all. (A pricey rider may raise the amount to $50,000.) "This has rocked our industry. It's a disaster for the affected owners," says Kim Anderson, vice president of Oswald Trippe & Co. "Mold and mildew insurance covers damage resulting from storms, broken piping and like events that cause direct damage to the insured structure. Mold-related damage from design and construction errors is not covered by property insurance at all."

To cure a sick house is, sadly, far harder than preventing the illness. To thwart mold contamination in your new home-or to determine if that existing home you have your eye on is a candidate for mold-you must understand the three main factors that contribute to its growth: inadequate climate control, inappropriate building construction and insufficient building industry awareness.

Proper climate control is more than making hot air cool. It promotes a safe, comfortable living environment through proper construction practices and equipment that reduces the risk of building-related illnesses. Unfortunately, there are more improper ways to control climate than there are proper ones-a problem made worse because most new houses today allow almost no fresh air inside.

Inappropriate building construction is endemic in sick houses. Hot, humid air finds its way inside the envelope (under the roof), moisture is trapped in walls by barriers, and water enters the envelope as leaks (mainly around doors and windows). Mold and mildew spores need water to grow.

Additional problems arise when standard air-conditioning systems fail to address tight building envelopes; cooling systems are often oversized and air filters are inadequate, designed to protect equipment not people. In Florida homes, ducts are generally located above the ceiling where it's hot-110 degrees-and muggy. When supply ducts leak because of improper construction, cool air blows into the hot attic and gets lost. A partial vacuum forms inside the home, and the air-conditioning unit sucks in humid outside air to fill the vacuum. This happens every second the system operates. When return ducts leak, they suck in hot, humid attic air that's often laced with mold spores, which colonize in moist duct linings. Then the air-conditioner blows the spores throughout the home because its low-grade air filter can't grab them.

Many builders and designers are from other parts of the country, and they may not understand that homes need to be built differently in Florida to accommodate the moist, hot climate. Architects are generally current on mold and mildew prevention, but many residential designers, drafting services and builders are not. Designers aren't obligated to meet any training or educational requirements, and builders are offered mold and mildew classes only as electives to their continuing education requirements. Building codes, meanwhile, are outdated on the

Still, there's hope for sick houses. Those with steeply pitched roofs (25 degrees or more) can possibly be foamed from inside, the old insulation removed and all vents to the outside sealed. If there's mold and mildew in the ducts, replacement is the only sure cure. Black walls need to be stripped clean, and possibly opened up, to eliminate mold spores. All of this is costly, but the reward is better health and property values.

Your best defense is to make sure your Florida home is designed and built to resist mold and mildew. If you're building a new home, become educated, and then ask for what you want. And careful due diligence is needed if you're buying a resale home. Check thoroughly; it's cheap insurance in view of the consequences.

Keys to a mold-free house

If you're building a home, there are certain steps you can take to reduce the risk of mold.

Read the Builder's Guide, Hot Humid Climates, available online at www.buildingscience.com. You'll be surprised and smarter. Give copies to your designer and builder. Insist that they read it and follow it.

Use sprayed-on, open-cell foam insulation like Icynene (learn more at www.icynene.com) around the living envelope and under the roof deck to prevent outside air under the roof. This will keep the hot, moist, moldy air outside so a leaky A/C system can't suck it in.

Use only ducts that have a biocide (mold-killing) lining. Ordinary cheap pink fiberglass ducts harbor spores and can't be cleaned thoroughly. ToughGuard is a good duct board.

Make sure outside air gets to your air-conditioning unit. Although codes don't require this, do it. Five to 10 percent of the volume is a good rule of thumb. Have a simple volume damper installed to regulate flow and pressure. This promotes fresh air and a slightly positive air pressure inside your home, which will keep vapor out, lower humidity and reduce moisture infiltration. (Checking for positive air pressure is as simple as opening the door-the air blows out.)

Make sure the air-conditioning system is slightly undersized and located inside. The house will need less cooling due to the insulation wrap, and the air-conditioning unit will run for longer intervals, reducing the amount of humidity the cooling coil will hold. Lower humidity helps you tolerate higher inside temperatures and leads to smaller electric bills. Molds don't like low humidity.

Use a world-class air filter like Aprilaire (www.aprilaire.com), which traps almost everything.

Don't allow plastic house wrap, plastic-backed insulation or wallboard, impermeable (elastomeric) paint or vapor retarders of any kind to go on your exterior walls or ceiling. Avoid wallpaper on any outside wall.

Pick your building team as you would your doctors. Quiz everyone about their knowledge of healthy houses and how they get that way. If you don't like what you hear, move on. Be fussy. Some industry pros know the way to fight mold and mildew; seek them out.

TIPS

1. If you're buying a resale home, open your eyes. If you see ventilation openings on the underside of the eaves, or feel a hot, clammy attic, this house has the potential for getting sick. Double your due diligence effort and get a thorough examination by a mold and mildew inspection expert.

2. Follow your nose. If it tells you something's wrong, the house is probably sick. Think about moving on.

3. Keep in mind that mold and mildew evidence may not be readily apparent during the winter season, when the air conditioner is used more sparingly and the house is left open.

4. Look at the plans to see how the walls of the house were built. You don't want to see danger words like "membrane, shield, barrier, plastic or wrap."