Steps for Inspecting & Remediating Your Home For Mold & Water Damage

Perform post-remediation verification (clearance testing) of work areas. This is typically done by a third party such as an IEP.

Why is post-remediation verification (PRV), also known as post testing or clearance testing, a critical part of the remediation process?

Post-remediation verification (PRV) is an important part of determining if remediation was successful. As tempting as it is to skip this step to save money, don’t do it! It is not enough to simply remove visible mold growth; you want to confirm that any mold growth and its byproducts are actually gone at a microscopic level.

If the third party performing the PRV determines the remediation has “failed,” the remediation company should come back and reclean or remediate the area at no additional cost to the client. This is standard industry practice.

Prior to remediation starting, it is important that you, your Indoor Environmental Professional (IEP), and your remediation company agree in writing what constitutes a “pass” or “fail.” Further, if the containment does fail, it should be clear what steps the remediation company will take to remedy the situation (i.e. they will come back to reclean or remediate the area at no additional cost to the client).

Who can perform post-remediation verification?

Generally speaking, do not let the company doing the remediation also do the PRV. It is important that this testing is done by a third party, such as an IEP. Why? Because testing can be manipulated to downplay (or to exaggerate) results. A company that is doing both the remediation and the post testing may be tempted to perform testing in a way that favors a positive result for themselves. If an area “fails” and a remediation company has to reclean or remediate at no additional cost to the client, the additional time, money, and resources comes out of their own pocket.  

Bottom line: Using the same company to remediate and perform PRV poses a potential conflict of interest and is even illegal in some states!

When and what should post-remediation verification include?

Since these industries are not very regulated, it is critical for you, your IEP, and your remediation company to agree ahead of time and in writing who can perform PRV, when PRV can be performed, how it will be performed, and what constitutes a “pass” or a “fail.”  

Generally speaking, the PRV should take place within a few days of remediation being completed and before containment and other engineering controls are removed. Do not remove the containment and engineering controls until after your third-party IEP has determined the area has “passed.” Otherwise, you risk exposing the rest of your home and belongings to any contaminants that are left behind. Even good remediation companies have projects that fail the PRV the first time. After all, they are dealing with microscopic particles! 

It is also important to determine what conditions are required during testing (i.e. air scrubbers on/off for a period of time prior to testing) as well as what types of tests are acceptable, along with the criteria that will determine what constitutes a “pass” or a “fail.”

Three Components of Post-Remediation Verification:
  • Visual inspection and moisture measurements
  • Air testing
  • Surface samples
At a minimum, a “pass” should meet Wonder Makers Environmental's “Post Remediation Evaluation Criteria for Mold Contamination” which has been reprinted in our FREE guide “Mold Remediation at a Glance.”

Visual inspection:

There should be no visible debris inside the containment. This means the floor and building materials are free of dust, scraps, loose nails, and other debris like trash. 

Your third party should be able to put on a white glove and rub it along any surface inside the containment and the glove should remain white. If there is visible debris or the area fails the white glove test, it should be an automatic “fail” because it is unlikely that the remediation company cleaned sufficiently. (Learn more by downloading our free resource “Mold Remediation at a Glance” here or at

Air and surface samples:

It is important to note that there are no regulations pertaining to thresholds or amounts of mold or bacteria that are safe for an indoor environment. Meaning, there is no standard (federal, health, or otherwise) that says that “X” amount of a mold or bacteria is safe while “Y” amount is not.

When it comes time to analyze the test results, it is best to pay attention to the specific types of molds and their amounts in relation to your unique situation. 

Unfortunately, many IEPs and remediation companies use a very rudimentary comparison between outdoor air samples and indoor air samples to determine if a remediated area has “passed” or “failed.” This scenario has many drawbacks, as it assumes that as long as the total indoor spore count is lower than the total outdoor spore count, then the remediation was successful. It does not take into account individual types of molds and their amounts. For example, if there are certain elevated molds present indoors that are not present outdoors, it can suggest that there is still a problem inside the contained area. Sometimes this happens because more cleaning is needed, and other times it happens because areas of growth were missed. 

At a minimum, we suggest using the criteria from Wonder Makers Environmental’s “Post Remediation Evaluation Criteria for Mold Contamination” which has been printed in our free guide "Mold Remediation at a Glance."  

This criteria identifies five zero tolerance molds: Stachybotrys, Fusarium, Trichoderma, Memnoniella, and Chaetomium. Using this criteria, the presence of even a single spore of these five molds on either the air or surface testing results in an automatic fail. These molds are indicators of water damage; they should not be showing up on a PRV inside a containment.

Zero Tolerance Molds

  • Stachybotrys
  • Fusarium
  • Trichoderma
  • Memnoniella
  • Chaetomium

Note: The criteria for occupied living spaces such as family rooms, kitchens, laundry rooms, bathrooms, basements, or general living areas is different from criteria for unoccupied living spaces such as attics and crawlspaces.


Your remediation contract should include important details such as who can perform post testing, when it can be done (within X number of days of completion, etc.), what conditions are required (air scrubbers on/off during testing, etc.), and most importantly, what constitutes a “pass” or “fail”.

Additionally, many remediation companies explicitly forbid unauthorized personnel (including you and any tradespeople) from entering the containment at any point during the process (even after workers have gone home for the night). Unauthorized personnel risk cross-contaminating both inside and outside the containment. If this occurs, some remediation companies will no longer guarantee that their work will pass post-remediation verification.

To learn more about what should be in your contract, download our free resource on “Mold Remediation Contracts” at

How can you find a third party to do post-remediation verification (PRV)?

Your IEP can perform post-remediation verification. Refer to the information in Step 1 and use the questions below. 

Word of caution: 

  • Do not let the company that performed the remediation also perform the post testing. It’s a potential conflict of interest and is even illegal in some states!
  • Do not hire a remediation company that only guarantees the remediated area will pass a visual inspection.
  • Do not rely on “total” indoor spore count being lower than “total” outdoor spore count as the criteria for “passing” a remediated area.

How do you prepare for post-remediation verification?

  • Contact your third-party IEP once you have a good idea of when remediation is to be completed. Schedule the PRV within a few days of completion. Note: check your remediation contract for specifics. 
  • Keep containment and engineering controls up until after the area has “passed” post testing. 
  • Make sure no unauthorized people enter the containment. This includes you and any tradespeople. Your IEP should take proper precautions when entering and exiting to perform post testing.
  • Be sure you, your remediation company, and your IEP are all in agreement prior to beginning remediation about the who, when, what, and how of post testing.

Additional resources:

  • Mold Remediation Mini Class Series (Coming Fall 2024)