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Expert tips for preventing mold growth or remediating mold in your home after a flood


Mold, especially toxic black mold, growth is a big concern after a flood.

Experts say even if a home was not flooded, being without power and air conditioning for more than 72 hours can create conducive conditions for mold growth in a structure and resultant health concerns.

With over 100,000 species, the color, shape or size of the mold to the naked eye cannot tell you whether mold is toxic or not.

That's why it is crucial to have lab testing performed from a mold inspection.

"Staccibatrus which often is referred to as 'black mold' is a slow-growing, but quite dangerous mold," Carl Carlson, managing partner for Green Home Solutions, said.

Carlson said to keep in mind that other species of mold can elicit an allergenic response in a human as well.

"Molds don’t need to be any particular color, and all have the potential to cause respiratory distress like asthma and sinusitis or more pervasive infections in the immuno-compromised, plus all molds produce toxins that allow them to survive but which are known to be toxic to humans and pets," Dr. Cameron Jones, director of Biological Health Services and a consultant on indoor air quality and environmental microbiology.

Preventing or remediating mold growth after a flood disaster

Experts say the number one thing you must do to to prevent mold is remove and replace all water-damaged building elements.

"Whilst this is sometimes alarming news, once floodwater has saturated drywall, wall insulation and flooring timbers, mold will immediately begin growing after the water subsides," Jones said.

Black mould on a wet wall

Black mold buildup in the corner of an old house. (Urban78/iStockphoto/Getty Images)


Jones said the technique of 'remove and replace' is better than using disinfectants and biocides is because mold contamination quickly leads to massive levels of spores being produced as buildings begin to dry out due to their asexual reproductive life cycle.

"These spores are often highly toxic due to mycotoxins and can cross-contaminate a house if it is incorrectly dried using heaters or blowers without adequate containment," Jones said.

Jones said once mold is visible and it covers several meters, you have a big problem and should engage a professional.

"...removal of water and compromised building materials is what is done first. Drying out and preparing for mold treatment comes next," Carlson said.

It is always important to wear appropriate clothing for any cleanup operation such as gloves, a P3 half face respirator with a micron filter, goggles and disposable coveralls. Women who are pregnant, children, the elderly and the immuno-compromised should not spend time inside mold-affected buildings and should minimize contact with mold-affected personal property.

"It may also be beneficial to use a HEPA air scrubber or filter to physically extract the ambient mold spores and cell wall fragments to minimize aerosolization of these fine, toxic particles into the air."

Experts say you should also be very careful when engaging mold remediators who claim they can use non-toxic fogs or gases or sprays to decontaminate your home.

"Anything non-toxic won’t have enough chemical energy to do useful work, and in this case, killing the fungus but leaving it behind, solves only half the problem, since the mold that remains may still cause allergy or unwanted toxic reactions. Therefore, be extremely cautious with claims that sound too good to be true. The same goes for mold inspections and assessments"

sewage flood home restoration

This is the sewage water damage recovery process in a residential home. The flooring is ripped off, and the rooms are sprayed with biowash. Industrial fans and dehumidifiers is placed in the room for the drying and restoration process. The process will last three days. (Ceneri/Getty Images)


If you engage a professional to inspect your home, you want to ask questions regarding how their sampling will lead to comprehensive testing of the whole home.

If the inspector doesn’t take adequate outdoor controls or only samples one or two rooms, then the report is hardly going to provide answers to the potential risk posed by each room and the basement and the attic or roof void.

In many cases, the role of inspections and assessments is to provide a forensic level assessment of the likely risks from mold cells and spores and how these may impact on the built environment.

Remember the fewer the samples taken at an inspection, the lower the quality of the overall recommendations. In many cases, an extensive removal of the water-damaged building materials is the only sensible approach to removing the dangers posed by mold and their spores. Usually the more porous the material, the less likely they can be successfully salvaged.

Most branded mold disinfectants sold commercially are mainly useful for small mold-affected areas and were not designed for homes that have suffered severe water damage. If you want to use a disinfectant, then preferably use an intermediate or high-level hospital grade disinfectant that is registered with the EPA and rated as suitable against bacteria, fungi and viruses.


These products normally state that they are bactericidal, tuberculocidal, fungicidal (against asexual spores but not necessarily dried chlamydospores or sexual spores) and virucidal.

Consult with a specialty chemical supply store in preference to using domestic-grade products like vinegar or bleach, which cannot be relied on to destroy within a practical period of time those bacteria, fungi, spores or virus that may be present in water-damaged homes.

The Institute of Inspection, Cleaning and Restoration Certification Mold Remediation provides a specific set of practical standards for water damage restoration and more information can be obtained at www.iicrc.org.


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