Cleaning up Molds after Flooding and Hurricanes

Excerpts FEMA advisory No. 1493-24 "Hurricane Isabel Carried A Hazardous Potential For Mold" last updated 28-Jun-2005:

The Mold Danger after Flooding

According to The Journal of the American Medical Association (JAMA), mold growth in water-damaged homes is a potential hazard from flooding.

Exposure to high spore levels can cause the development of an allergy. Mold can also cause structural damage to your home. Similarly, when wood goes through a period of wetting, then drying, it can eventually warp and cause walls to crack or become structurally weak.

Mold could become a problem in your home if there is enough moisture available to allow mold to thrive and multiply. Dampness in basements, walls, carpets, and wood caused by flooding provide an environment for mold to flourish. You can also be exposed to mold through skin contact and eating.

For some people, a relatively small number of mold spores can cause health problems. The basic rule is, if you can see or smell mold, take steps to eliminate the excess moisture, and to cleanup and remove the mold. It is important to quickly identify and correct any moisture sources before health problems develop. Infants, children, immune compromised patients, pregnant women, individuals with existing respiratory conditions, (allergies, multiple chemical sensitivity, and asthma) and the elderly appear to be at higher risks for adverse health effects from mold.

You can tell if you have mold in your home if you can see it, or if there is an earthy or musty odor. Allergic individuals may experience the symptoms listed above. Visible mold growth is found underneath materials where water has damaged surfaces, or behind walls. Look for discoloration and leaching from plaster.

Cleaning up Molds

Before beginning work on a flooded home, make sure the electricity is turned off. Unplug appliances and lamps, remove light bulbs and cover plates of wall switches or outlets that got wet. If local building inspection code allows you to disconnect wiring from switches and outlets, do so and throw them away. If your building inspector says that you cannot disconnect the wiring, pull them forward, away from the wall, and leave them connected.

  • Remove as much mud as possible. Once you have checked the water system for leaks, hose down the inside of the house and its contents. It is best to use an attachment that sprays soap to wash and rinse the walls, floors, furniture, sockets, electrical boxes, and other major items that got muddy. Use a non-ammonia soap or detergent, or a commercial cleaner in hot water and scrub the entire area affected by the mold. A stiff brush or cleaning pad works well on block walls or uneven surfaces. Rinse clean with water. A wet/dry vacuum is handy for this process.
  • Remove heating and cooling registers and ducts, then hose them to prevent contamination when blowing through the ducts at a later date. Next, scientists recommend washing with a disinfectant that is quaternary, phenolic or pine-oil based. If ducts are in a slab or otherwise inaccessible, have them cleaned professionally.
  • Disinfect and dry the moldy area. It is critical to remove the source of moisture, before beginning to clean up, as mold growth will return, if the area becomes wet again.
  • Bag and dispose any material that has moldy residues, such as rags, paper, leaves, or debris. Harder materials such as glass, plastic, or metal can be kept after they are cleaned and disinfected.
  • Wear gloves when handling moldy materials. Moldy materials should be removed as follows:
  • Remove porous materials (examples: ceiling tiles, drywall, carpeting, wood products)
  • Carpeting can be a difficult problem - drying does not remove the dead spores. If there is heavy mold, consider replacing.
  • Allow the area to dry 2 or 3 days.
  • If flooded, remove all drywall to at least 12 inches above the high water mark.
  • Visually inspect the wall interior and remove any other intrusive molds. (This step may have to be carried out by a licensed contractor).
  • Use caution, as spores are easily released when moldy material is dried out. When cleaning these damaged materials, consider wearing a mask or using a respirator. Respirators can be purchased from hardware stores; select one for particle removal (sometimes referred to as a N95 or TC-21C particulate respirator). Respirators are not as effective removing bleach fumes, so minimize your exposure when using bleach or other disinfectants.
  • After thoroughly cleaning and rinsing, disinfect the area with a solution of 10 percent household bleach (e.g., 1 1/2 cups bleach per gallon of water). Using bleach straight from the bottle will not be more effective. Never mix bleach with Ammonia - the fumes are toxic. Avoid excessive amounts of runoff or standing bleach. Make sure the working area is well ventilated. st. If you feel that this adversely affected your health, you should consider paying a licensed contractor or professional to carry out the work.
  • Ask others to leave the areas during the cleaning process.
  • Work over short time spans and rest in a fresh air location.
  • Air your house out well during and after the work.

Never use a gasoline engine indoors - you could expose yourself and your family to carbon monoxide.

If mold odors persist, continue to dry out the area and search for any hidden areas of mold. If the area continues to smell musty, you may have to re-clean the area. Continue to dry and ventilate the area. Don't replace flooring or begin rebuilding until the area has dried completely.

Our Recommendations

Spray our BioZap Mold and Mildew Cleaner on visible mold and mildew stains, let penetrate and work for about 15 minutes. Severe stains may require repeated applications. Wipe off and apply a light spray for prevention. BioZap uses essential oils of the Australian Tea Tree, contains no chlorine or bleach, and does not release toxic fumes. It is safer to your health and the environment than chlorine or other bleaches.

Place several jars of BioZap Air Purifier & Deodorizer in the affected areas. Its vapors will attack the invisible molds in the air and in porous surfaces, as well as break down musty odors.

Seal all concrete that has been flooded or that is underground with RadonSeal penetrating concrete sealer. It will purge from the pores in concrete dirt and organic matter, which promotes molds. It will stop musty or earthy odors emanating from the concrete or the dirt below. And it will seal the concrete against moisture and deny the mold spores a place to grow. After sealing, shop-vac the purged dirt.