LAKELAND -- Think of mold as an unwelcome guest. It's just waiting to move in to your home, settle in, and at best, be a nuisance but at worst, a source of illness. It's during the construction process that homes can be the most vulnerable to the black and green spores. Incomplete structures are left open to the elements, including the most worrisome of all -- moisture -- something vital to mold growth.

While a homeowner depends on the contractor to ensure the integrity of a new home, sometimes things go wrong.

In 2002 alone, insurance companies across the nation paid $3 billion in mold insurance claims. That amount was primarily homeowners insurance claims, said Carolyn Gorman, vice president of the Washington office of the Insurance Information Institute.

Homeowners who build in Florida face challenges in warding off mold; the most important being the state's typically hot and humid climate.

Joseph Lstiburek has a doctorate in building science, is a forensic engineer and is a principal of the Building Science Corp., an architecture and building science consulting firm in Westford, Mass. He spoke at the 2003 Southeast Building Conference in Orlando in July and emphasized the difference between building in the North and South -- an important issue in this state, where many northern residents, in search of a little warmth, choose to settle.

Among Lstiburek's "Top Ten List of Dumb Things to Do in the South," he names the use of lined ducts.

"You can never clean them. When they are wet and dirty they grow bad stuff," he writes on his Web site, www.buildingscience.com. "They get wet and dirty. When they are wet and dirty and when they grow bad stuff the only thing you can do is throw them out. At least you can clean and decontaminate the metal ducts."

Another of his rankings is the use of a vapor barrier on the wrong side of the wall. In the South, the barrier should be used on the outside of buildings but in the North, it goes on the inside. The reason for the difference, Lstiburek said, is that moisture flows from warm to cold. In the South, that means moisture would travel from the outside to the inside of the home. By putting a vapor barrier on the inside of a wall in the South, moisture will travel through the wall, then get trapped. That's a condition ripe for growing mold.

The average homeowner may not know a great deal about vapor barriers and lined ducts. But a little knowledge can be a homebuilder's best weapon against mold. For Mold 101, local builders offered their advice for protecting a home during construction.

GETTING TO KNOW MOLD

Mold is a kind of fungus and is a decomposer of dead organic material like leaves, wood and plants. It can sometimes infect living plants and animals. The spores and hairlike bodies of mold colonies sometimes can't be seen without a microscope. It can appear black or green but if growing behind vinyl wallpaper, may be pink or purple, according to Building Science Corp.

Mold grows where there is water, oxygen and a temperature of between 40 and 100 degrees. It can make a home on wood and drywall. Mold can't get the nutrients it needs from inorganic things like concrete, glass and metal but it can grow on the dirt present on such surfaces. Mold can get moisture from the air when it's very damp -- especially when the relative humidity is 80 percent or more.

Under certain conditions, mold can cause allergies and asthma attacks.

PREVENTING MOLD DURING BUILDING

The No. 1 thing new homeowners should remember when touring the site of their soon-to-be-completed home, is that wallboard needs to be protected.

"The roof system needs to be properly installed before anything can be put inside the house that shouldn't get wet," said Jimmy Waller of Waller Construction in Lakeland.

"What happens on a lot of new homes is they put the Sheetrock in before the roof is even done."

Mark Hulbert of Hulbert Homes suggests owners tour the site of their new dwelling during a rainstorm after the roof is in place but the interior is still unfinished.

"You need to make sure nothing's leaking," Hulbert said. "By going there when it's raining, if you have a very slow leak behind a wall or a window, that can be a problem. If you catch a building defect early you can lessen your chances of having a mold problem."

As for wood framing, which typically is installed before a roof is put in place, Waller said that it's OK for it to get wet but it shouldn't be left exposed for a long time.

Greg Masters, president of the Polk County Builders Association and vice president of Southern Homes of Polk County, agreed that it's OK if homeowners see damp wood on their site.

"Lumber is outside for the most part," Masters said. "The fact that lumber gets wet or trusses get wet isn't something that you need to be concerned about."

What homeowners do need to make sure of is that the grade of their home during the construction process is such that moisture will be directed away from the slab.

"Make sure the grade of the yard has water flowing away from the house because standing water will create mold," Masters said. "Make sure that there is a slope away from the house."

Lstiburek agreed and said that gutters should be installed as early in the building process as possible.

"You don't want water to saturate ground near the home," he said. "You want it go away from the house and be the neighbor's problem."

Masters also said that homeowners should make sure that the height of their slab (or floor for those not used to construction lingo) is 8 inches to 10 inches above the ground around the home -- giving it a buffer of from water that will gather around a home's base.

Masters emphasized that mold is a much bigger problem with wood frame homes than it is with block structures, which is mostly what his company builds.

Homeowners should also watch out for tile that's affixed to green board -- a piece of gypsum board coated with wax to make it waterproof.

Lstiburek said that method just doesn't cut it.

"Tile should be affixed to cement board," he said because cement is a drier and less friendly environment for mold growth.

The key to preventing mold growth, be it in a home still in the construction process or a home decades old, is to keep it dry.

To achieve an arid environment, exhaust fans should be mounted in bathrooms and kitchens -- where mold often grows. Air from a clothes dryer needs to be exhausted away from a home and humidifiers should be used as little as possible.

Mold spores can grow within 48 hours after a water leak. Make sure such leaks are dried quickly.

And Lstiburek said air conditioning is vital to combatting mold.

"Air conditioners are one of the few things that's better when smaller," he said. "Smaller ones will run longer and will be a better dehumidifier."

Another thing to keep in mind, Lstiburek said, is the lack of air that circulates behind pictures and mirrors. In France, he said, home owners once used a piece of cork to separate hanging pictures from the wall -- allowing air to flow and therefore preventing mold to grow.
 

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