Fixing water damage
Rhonda Gordon, Special to the Gazette
Saturday, May 9, 2009
Friday’s flash flooding brought many calls to our office about how to clean up water in basements and other indoor areas.
Proper drying and cleaning is important to avoid health problems associated with mold, which likes dark, damp areas.
After a flood, fire, or water leak, walls and floors that were soaked for more than a few hours may have absorbed large amounts of water. These areas must be cleaned, dried, and disinfected. If necessary, remove the wall board and flooring materials to dry out these areas.
Mold has been found growing in wet insulation several months after a flood. Remove and discard wet insulation. The insulation and the wooden studs may be wet for two or more feet above the flood's high-water level because of absorption by the materials and wicking to other areas.
Organic matter from flood water must be cleaned up. Using a solution of detergent, water and trisodium phosphate, scrub all contaminated areas with a brush and rinse thoroughly. Scrub any exposed wood in the wall cavities with a detergent before disinfecting and drying.
Use fans, dehumidifiers, and air conditioners to dry a wet area. If using a dehumidifier, empty the water collection pan frequently or drain it through a hose to a floor drain. Mold can grow in the water standing in the collection pan. Air conditioners remove moisture from the air and help promote drying. If the outdoor air is dry, leave a window open to promote drying. Several weeks or months may pass before soaked walls and floors are dry enough to re-insulate and re-install wall board or flooring.
Discard wet materials that cannot be dried quickly: Carpets and carpet padding, draperies, mattresses, box springs, and upholstered furniture that have been soaked or stored in a damp environment are nearly impossible to clean and dry quickly enough to prevent mold growth. Mold thrives under wet carpet or padding and inside mattresses and upholstery. If these products have only a small amount of mold growth on the surface, they may be dried in the sun. Sunlight kills mold but it may also fade textiles, therefore sun drying may be a method of last resort in attempting to save items that are about to be discarded.
Disinfect it: Disinfectants kill mold growing on hard surfaces, such as walls and hard floors. Products that claim to be disinfectants must be registered with the Environmental Protection Agency and have an EPA registration number on the product label. Only products with the EPA registration number have been tested as disinfectants. Read labels and choose a product that disinfects and is appropriate for the material being treated.
One of the most effective and least expensive disinfectants is chlorine (sodium hypochlorite) bleach. Check the label and use only bleach with 5.25 percent sodium hypochorite. Following the directions on the label, a bleach solution can be applied to hard, clean surfaces. The walls should be thoroughly cleaned with a detergent solution before disinfecting.
For many hard surfaces, disinfecting with a solution of one cup of bleach to one gallon of water is effective. The area must be kept wet with the bleach for 10 to 15 minutes to kill the mold. If the surface is porous like wood, the bleach solution may need to be reapplied to keep the surface wet for the required time. If large areas of a basement need to be disinfected, a garden sprayer can be used to apply the bleach solution to the walls. If the walls have been contaminated with sewage, increase the proportion of bleach to water.
During a long drying period, such as after flooding, it may be necessary to use the disinfectant every few days until the wood is no longer damp. The bleach solution kills mold only for the few minutes before the bleach evaporates. Because mold spores in the air that settle on the wet wood can germinate and develop a new colony of mold, a surface will not remain mold-free just because it has been treated once with bleach. Covering wet wood with wall board or flooring material will not stop the mold growth, as mold does not need light to grow.
After a flood, test whether wooden studs in the walls are dry enough to reseal the wall cavity by inserting a moisture probe into the wood. If the level of moisture in the wood is above 12.5 percent, continue drying the wood before resealing the wall cavities.
Never mix bleach with ammonia or other household cleansers containing ammonia. When cleaning with chlorine bleach solution, wear rubber gloves and protect skin. Avoid contact of the solution with the eyes and skin and avoid prolonged breathing of vapors.
Some products will disinfect hard surfaces but are ineffective for disinfecting textiles. To be sure that textiles that can be laundered are disinfected; use products with the EPA registration number and with specific directions for disinfecting laundry. Two types of disinfectants that are effective on fabrics are chlorine bleaches (5.25 percent sodium hypochlorite) and quaternary compounds.
When caring for textiles, directions provided on the care label should be carefully followed. Some textiles are harmed by chlorine bleach and labels on those products indicate that chlorine bleach should not be used. Liquid chlorine bleaches are safe for most fibers except wool, silk, or resin coated fabrics, but often cause color fading as do quaternary compounds. Test any disinfecting compound on an inconspicuous portion of the textiles before applying to the entire product. For some textiles, such as leather, none of the disinfectants discussed above are appropriate
Pine oil cleaners and phenolic cleaners are considered safe for textiles and are often recommended for their disinfecting action. Many formulations of these compounds, however, only reduce the mold and number of bacteria and do not totally disinfect textiles. For example, a pine oil cleanser should be at least 70 percent pine oil to disinfect textiles. Most formulations sold are much lower concentrations.
If you are storing items in your basement, keeping boxes elevated on pallets is a good idea. If you have paper items that have gotten wet, they need to be laid out in a single layer to dry. Pages of books will have to be turned to let the whole book dry.
Remember, to prevent mold, keep it clean and keep it dry. After contamination, to prevent and remove mold: Clean it, dry it, and disinfect it. Unless these methods are used, mold may continue to plague homes. We do have a publication available at the Extension Office about “Controlling Mold Growth in Your Home.”
F For more information on this column, nutrition, e-mail her at rgordon@ksu.edu or call the Lyon County Extension Office at 341-3220.