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UF Experts: Long After The Storm, Mold Can Threaten Homes

Jim Kimbrough, 352-392-2158
Audrey Norman, 561-233-1742

GAINESVILLE, Fla. — Even after they ride out this year’s hurricanes, Florida homeowners may still have another enemy to fight.

Mold, always a threat to homes and property in the humid Sunshine State, is becoming a major problem for people who have faced flooding or roof leaks during this busy storm season, University of Florida experts say.

“Mold can be more than just a minor nuisance,” said Jim Kimbrough, a professor of plant pathology and mycology at UF’s Institute of Food and Agricultural Sciences. “Molds can cause allergic reactions, and in rare cases, even fatal illness.”

Almost all of Florida has been directly affected by landfalling hurricanes this year — creating flooding, leaks or plumbing problems for people around the state. But even after the standing water is gone from your house, lingering moisture can foster the growth of mold that can make a house unpleasant or even uninhabitable.

The good news, UF experts say, is that property can be rescued from all but the toughest mold problems with lots of work and the right equipment. Their first and most important rule: dry everything.

“The best way to stop these organisms from growing is to get everything as dry as you can,” Kimbrough said. “It’s important to note that mold spores are in your house all the time: they grow only when you provide them the right conditions.”

Kimbrough advises using a wet/dry shop vacuum, if you can, to pull water out of carpets and other soaked areas and objects. If you can’t get a carpet dry within 48 hours, he said, you’ll probably have to pull it out and throw it away, he said.

But most other items should be salvageable — particularly if you have electricity and a working air conditioner.

To dry your house, Kimbrough said, you should first set the thermostat to 90 degrees, allowing the heat pump to warm the room for a couple of hours. Since warm air holds more moisture than cold air, the heating will allow moisture to evaporate into the air from furniture and walls.

After two hours at 90 degrees, you should turn the temperature down to 70 degrees — allowing the air conditioner to remove some of the moisture from the air. You may need to repeat the process for several days, until the relative humidity in the house is 70 percent or lower.

If you don’t have central heating and air, heaters and de-humidifiers can serve the same purpose, said Audrey Norman, a UF extension agent for Palm Beach County, who instructs local residents on how to deal with mold problems. Whatever option you choose, she said, you should tackle a mold problem as soon as you can.

“Molds can grow rapidly, and they can grow on just about any surface — clothes, shoes, and furniture — that you have in your house,” Norman said.

If you lack electricity or access to a generator, she said, your best bet is to use chemical inhibitors such as paraformaldehyde or parachlorobenzene to stop mildew from growing. Both chemicals put off fumes that inhibit fungal growth, Norman said, though both should be used only when a house is NOT occupied.

Make sure you use either chemical as directed, Norman said. If you use too much, either chemical can change the dyes in your carpet or furniture.

While most mold varieties cause allergic reactions at their worst, one species, Stachybotrys chartatum, can be deadly. A black fungus which grows in drywall, dried plants, cardboard and other objects that contain cellulose, Stachybotrys puts off toxic fumes that can cause fatal illness in small children.

“Deaths from Stachybotris are rare, but where they have occurred, they’ve been linked to buildings where there was extensive growth of the mold,” Kimbrough said. “That’s a good reason to act quickly when you develop a mold problem.”

Homeowners shouldn’t panic if they spot a small amount of black mold, he said, because not all black molds are Stachybotrys.

Kimbrough said mold isn’t likely to cause serious structural damage to a house. Some molds do consume wood, he said, but those molds survive only when the water content of the wood is very high. Unless you have standing water in your house, he said, those molds aren’t likely to grow.

“There are businesses that specialize in mold removal, and often they’ll tell customers that they have mold in their walls that needs to be removed,” Kimbrough said. “I’d be very cautious about taking extreme measures. Just about every house has mold in the walls, but not every house has a serious mold problem.”

Some tips for removing mold from common household surfaces and items:

  • Clothing: As soon as you discover mildew, take the clothes outdoors and brush off the clothing. Allow the clothes to air in open sunlight; the ultraviolet rays in sunlight will kill mold. Then launder or dry clean the garments.
  • Leather goods: After testing the item for colorfastness, wipe the leather with diluted alcohol (a mixture of equal parts of water and denatured or isopropyl alcohol.) Allow the item to dry in an area where air is circulating. If mildew remains, wash quickly with suds from a mild soap or detergent, or saddle soap. Wipe with a damp cloth and allow the item to air and sun thoroughly. Polish or condition the leather after cleaning to protect the leather from splitting or cracking.
  • Books: If books or papers are damp, allow them to dry in a breezy and dry place. Take them outside and brush off any loose mold with a dry, clean cloth. To remove stains, wipe books with a cloth that has been soaked in suds and wrung out. After removing the stain, pat the area dry with a soft, dry cloth. Try not to wet paper, and do not scrub. Spread the pages of books fanwise to dry in an airy place and sprinkle with corn starch or talcum powder. Leave several hours, then brush.
  • Upholstered items: Remove mildew from the surface of the item by vacuuming or dusting (be sure to dispose of the vacuum bag, which will contain mildew spores.) Dry the item in the sun as soon as possible. If mildew remains, sponge with a cloth moistened with diluted alcohol. Dry thoroughly.

More detailed instructions on cleaning a wide variety of items can be found on the UF/IFAS website at