Once a flood has subsided, Mr. Weingartner said, the house must be dried out as quickly as possible. "Mold will start to grow within 48 to 72 hours," he said. Carpets, pads and furniture that were submerged should be removed, and drywall that was soaked should be cut out and discarded. Jeffrey Gross, a regional manager for Maxons Restorations in Manhattan, said there are three methods for drying out a wet house. The most basic, he said, is to get air circulating through it by using fans.
Another method that is faster and more effective, but more expensive, is to use dehumidifiers.
"Dehumidifiers are used to remove deep imbedded moisture," he said. "If you have a wood floor, or if the framing in the walls has been saturated, a dehumidifier will pull the moisture out of the wood." And while it is helpful to leave windows and doors open when using fans to dry out a building, they should be kept closed when using a dehumidifier. "If humid outdoor air is allowed to enter the home, the dehumidifier will be fighting against the relative humidity outside," Mr. Gross said. He added that a dehumidifier in a closed room can reduce the relative humidity to a low of 20 percent.
"When the air is that dry," he said, "it will wick moisture out of the walls and floors." Another way to dry out a house is to use the heating system along with the central air-conditioning system or window units.
"Warm air will hold more moisture than cooler air," Mr. Gross said. So a homeowner can close all doors and windows and run the air-conditioning. Once the house has cooled and the air is dry, the air-conditioning should be turned off and the heat turned on. When the temperature has reached, say, 80 degrees or so, the heat should be turned off and the air-conditioning turned back on until all the warm air has been removed. The cycle should be repeated until the house is dry.