Avoiding Mold Hazards in Your Flooded Home

Claudette Reichel  |  9/5/2012 1:20:46 AM

A flood-damaged home requires special attention to avoid or correct a mold population explosion. Mold is likely to multiply on materials that stay wet for more than two or three days. The longer mold is allowed to grow, the greater the hazard and the harder it is to control. So, as soon as floodwaters recede and it is safe to return, don’t delay clean-up and dry out.

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 damages or clean-up costs.

Mold and Health: Molds produce spores that float and spread easily through the air, forming new mold growths (colonies) when they find the right conditions – moisture, nutrients (nearly anything organic) and a place to grow.

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, may suppress the immune system or have other effects. Some types of mold can produce mycotoxins in certain conditions, which can be present in live and dead 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 as a form of documentation. Professional mold remediation contractors may test before and after clean-up to provide evidence of the clean-up’s effectiveness.

To prevent mold growth after flooding:

Remove wet carpeting right away. It’s best to discard it, but if salvaged, clean, disinfect and dry quickly with professional equipment or outdoors. Never reuse flooded padding.

Cut away wet wallboard and remove all wet and damp insulation right away – even if wallboard appears to dry. Wet insulation will stay wet far too long, leading to the growth of hidden unhealthy mold and decay fungi inside the walls.

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 do not prevent regrowth.

Do all you can to speed the drying of subfloors, slabs and wall framing before replacing insulation, wallboard and flooring. Use air conditioning or heaters, fans, and better yet, a dehumidifier. Water damage restoration contractors with special equipment (dehumidifying blowers) can provide the fastest drying.

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. That would prevent further drying to the inside.

Mold Clean-up Guidelines

To clean up mold, follow these steps and refer to more detailed information available online at www.epa.gov/mold .

Minimize Your Exposure During Clean-up: People are mainly exposed to mold by breathing spores or fragments, and can also be exposed 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 -- including gypsum wallboard, insulation, plaster, 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 removing and discard it. Even if not moldy, all wet fibrous insulation and other materials that are unlikely to dry quickly should be removed and replaced.

Clean Surfaces: Surface mold on non-porous materials such as hard plastic, concrete, glass, metal and solid wood can usually be cleaned. Cleaning must remove, not just kill, the mold because dead spores can still cause health problems.

After cleaning, you may choose to use a disinfectant to kill any mold missed by the cleaning. In the case of sewage contamination, disinfection must be performed. On color-fast, non-metal surfaces, you may disinfect with a solution of 1/4 to 1/2 cup 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 with caution, never mix bleach with ammonia and test on a small area.

Speed Dry: Dry all wet materials as quickly as possible. Use air conditioning or heat with fans and dehumidifiers, if possible. 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 should wait until all affected materials have dried completely.

Do More Than Restore. You can reduce future damage and ordeal by restoring your home with flood resistant materials and elevating equipment where possible. Consider ceramic or solid vinyl tile flooring and wall assemblies that can be washed and dried with solid wood studs, plywood (no OSB), closed cell foam insulation, and paperless drywall with latex paint or removable wainscoting.

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