Can Mold Come Back After Mold Remediation?

By: Licensed Mold Assessor Brad Fishbein

February 9, 2023

Having mold in a home can be a nuisance, but to have mold come back after remediation is just straight demoralizing!

Can mold come back after remediation? it absolutely can but there are a few steps you can take to ensure the mold remediation process is done correctly and there is no recurring mold issue in your home or office building.

In this article, we will go over the reason why mold returns to home after mold remediation services have been performed and how to prevent mold from returning.

Causes of Recurring Mold Growth


As a mold assessor when I typically see mold return to home it's because of one of the following issues:

  1. The mold remediation contractor did not perform mold removal properly.

  2. The mold was cleaned up but the source of the mold problem was not

Improper Mold Removal Services

Mold remediation companies are popping up left and right.

In some areas of the United States, there is no licensing for professional mold remediation services while in other areas of the country, licensed laws are loosening to promote economic growth.

While that's good for the overall economy it's bad for the consumer. Finding the right mold remediation contractor has become increasingly difficult because the market is completely saturated.

While just about any professional can remove mold on building materials, taking proper precautions from cross-contamination is not always something that some of these companies take seriously. Microscopic spores can spread throughout the home if certain protocols are not replaced and it can potentially make the problem worse!

A bad mold remediation company may not remove enough of the water-damaged building materials as well. Not just anybody should be considered to perform mold remediation.

The Source Of The Mold Was Not Corrected


It should be a given that whatever caused the moisture problem and mold in the first place needs to be resolved.



But the thing about mold remediation contractors is they may not know the building science to correctly solve an issue.

Yes, if it's something as straightforward as a leaky window or a roof leak, it can be easy to just fix the window or roof but if there is an underlying problem such as a faulty HVAC system that is not dehumidifying properly, that's a situation that can cause returning mold that the removal expert may not be familiar with.

True Story: A client contacted me to come into their home that was $13,000 worth of mold remediation approximately three months earlier. The company that came to perform mold removal, did a process called micro-cleaning throughout the home cleaning every piece of content and every surface. Well, when I arrived at the property mold was once again on all their belongings and various building materials. The company that did the work resolved the mold issues but not the source. The source was the humidity level was way too high caused by an oversized HVAC system. The air conditioning was not staying on long enough and the average humidity was above 70% at all times which not only made the home smell damp but caused the mold to come back after remediation.

A few common issues where mold can mold come back after remediation are:

Poor Ventilation

Poor ventilation is one of the most common causes of recurring mold growth in homes. Without proper airflow, moisture can become trapped and create an ideal environment for mold to thrive. This is especially true in bathrooms or other areas with high humidity levels, such as laundry rooms or basements.

High Humidity Levels

Humidity that exceeds 60% provides a perfect breeding ground for mold spores to grow and spread quickly throughout the house.

Poor Drainage

I have been around homes where a leaking window or some other issue around exterior walls was incorrectly blamed for water intrusion into a home. However, a home's foundation can contribute significantly towards recurrent mold infestations as well. Water can find its way into the home's foundation and cause water damage to walls and floors.

Prevention Strategies for Recurring Mold Growth


Improving Ventilation In the Home

As we already talked about, a home that is properly ventilated is one of the most effective strategies for preventing recurring mold growth. Poor air circulation can cause moisture to build up and create an ideal environment for mold spores to thrive.

To improve ventilation, run the air conditioning unit regularly and install exhaust fans in bathrooms and kitchens. Additionally, using dehumidifiers can help reduce humidity levels in the home which also helps prevent mold growth.

Repair All Leaks

Water is mold's blood. Without it, a moisture problem can't arise mold contamination is a non-issue. To prevent returning mold, repairing leaks is crucial.

Waterproof The Home's Foundation

Putting a waterproofing compound around the home's foundation can ensure water doesn't get into the home's wall cavity where mold grows. Directing all water away from the home can prevent mold from returning.

Meet the author: Brad Fishbein is an ACAC council-certified Microbial Investigator. In the fall of 2012, he became a Licensed Mold Assessor in the State of Florida through the Department of Business & Professional Regulation. Brad has helped homeowners with over 5,000 successfully completed Mold Inspections since 2009.

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