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Avoiding Mold Hazards in Your Water-damaged Home

A water-damaged building requires special attention to avoid or correct a mold explosion. Molds produce spores spread easily through the air, and they form new mold growths (colonies) when they find the right conditions: moisture, nutrients (nearly anything organic) and a place to grow.

Mold can damage materials and health. The longer mold is allowed to grow, the greater the risk and the harder the cleanup. So as soon as the floodwaters recede and it is safe to return, don’t delay cleanup and drying.

Take photographs to document damages for insurance purposes, and get started. It is not wise to wait for the adjuster to see it in person. Most homeowners' insurance policies do not cover mold damage or mold remediation costs.

Although there is wide variation in how people are affected by mold, long-term or high exposure is unhealthy for anyone. Exposure to mold can trigger allergic reactions and asthma attacks. It may suppress the immune system or have other effects. Some types of mold can produce mycotoxins in certain conditions, which can be present in spores and fragments in the air. “Black mold” is a misleading term since many types are black.

Mold testing is not usually needed and is rarely useful to answer questions about health concerns. Some insurance companies and legal services may require sampling for documentation. Professional mold remediation contractors may test before and after cleanup to assess their efforts.

The best way to avoid mold hazards is to hire a licensed, trained and reputable water-damage and mold-remediation firm. After a flood, that may be difficult. Since many homeowners' insurance policies do not cover mold damage or mold remediation costs, many residents face having to do the cleanup themselves.

Preventing Mold Growth after Flooding

  • Remove wet carpeting right away. It’s best to discard it. If the carpet is salvaged, clean, disinfect and dry it quickly. Never reuse flooded padding.
  • Remove all wet insulation right away – even if wallboard appears to be dry. Wet insulation will stay wet far too long, leading to the growth of hidden, unhealthy mold and decay fungi.
  • Clean with non-phosphate detergents (any phosphate residue is mold food). If you disinfect, follow directions carefully and never mix bleach with ammonia or acids (vinegar). Disinfectants can kill molds, but they do not prevent regrowth. Surfaces contaminated with sewage or floodwater should be disinfected.
  • Do all you can to speed the drying of subfloors, slabs and wall framing before replacing insulation, wallboard and flooring. Use air conditioning, heaters, fans or, better yet, a dehumidifier. Water-damage restoration contractors with special equipment (dehumidifying blowers) can provide the fastest drying.
  • If possible, test the moisture content of studs and sheathing (using a moisture detector) before replacing insulation. Wood should drop below 20% moisture content by weight before you close the wall.
  • DO NOT use vinyl wallpaper. It will prevent further drying on the inside.

Mold Cleanup Guidelines

To clean up mold, follow the steps in Mold Removal Guidelines for Your Flooded Home  summarized below, and refer to the EPA guidelines: A Brief Guide To Mold, Moisture, and Your Home or Mold Remediation In Schools and Commercial Buildings. Both are available online at

Minimize Your Exposure During Cleanup
People are exposed to mold by breathing spores or fragments. Exposure can also occur through skin contact. Wearing gloves and a respirator that can filter mold spores (N-95 or better) is recommended.

Isolate Work Area and Ventilate to Outdoors

Disturbing mold colonies can cause a massive release of spores, so seal off the contaminated area from the rest of the house. If power is on, use a fan to exhaust air to the outdoors.

Remove and Discard Moldy Materials

Porous moldy or sewage-contaminated materials should be removed, bagged and thrown away. This includes insulation, carpet/carpet pad, ceiling tiles, processed wood products and paper. To minimize the spread of spores, cover moldy material with plastic to contain spores before removal.

Clean Surfaces

Mold on nonporous materials such as hard plastic, concrete, glass or metal and surface mold that has not penetrated solid wood, plaster and sometimes drywall can usually be cleaned. Cleaning must remove, not just kill, the mold because dead spores can still cause health problems.

After cleaning, a disinfectant may be used cautiously to kill any mold missed by the cleaning. In the case of sewage contamination, disinfection must be performed. Contact your local health department for appropriate advice.

On colorfast, nonmetal surfaces, you may disinfect with a solution of 1/4 to 1/2 cup of bleach per gallon of water. Do not use in the air system. Milder, less-corrosive disinfectants include alcohols, disinfecting cleaners and hydrogen peroxide. Always handle bleach with caution. Never mix it with ammonia; test on a small area before treatment.

Consider treating exposed wood framing with a borate solution or coating to provide some protection from termites and decay. It may also help deter the regrowth of new mold during drying.

Speed Dry
Dry all wet materials as quickly as possible. If possible, use air conditioning or heat with fans and dehumidifiers. New mold colonies can form in as little as three days if materials stay wet. Wood and other materials that look dry can still be wet enough to support regrowth.

Remain on Mold Alert
Continue looking for signs of moisture or new mold growth. If mold returns, repeat cleaning and consider using speed drying equipment and moisture meters. Regrowth may signal that the material was not dry enough or should be removed. Rebuilding and refurnishing should wait until all affected materials have dried completely.

For more information on restoring a flooded home, see Storm Recovery Guide for Homeowners booklet or Cleaning Flood-damaged Homes fact sheet available from LSU AgCenter offices or

Last Updated: 1/6/2015 10:54:53 AM
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