acceptable humidaty levels in gypsum?

[James E. Braun, CMI]

The reasons for air testing are:

1. To determine to the correct removal of the mold; How much area needs to be cleaned (if any), how should the areas affected be cleaned, does the HVAC need cleaning, etc.
2. Whether the cleanup of the mold was successful.
3. To help trained doctors pinpoint the cause of chronic symptoms or illnesses in patients.

Learning to read air samples is about the most difficult part. For the first year, I called my Industrial Hygienist and verified every single lab report to make sure I was reading them right. I still do but only if something showed up on a lab result that is not normally found in the air, also for all clearance samples of mold remediation jobs.

[Brian A. MacNeish]

Originally Posted by jbraun

The reasons for air testing are:

1. To determine to the correct removal of the mold; How much area needs to be cleaned (if any), how should the areas affected be cleaned, does the HVAC need cleaning, etc.
2. Whether the cleanup of the mold was successful.
3. To help trained doctors pinpoint the cause of chronic symptoms or illnesses in patients.

Learning to read air samples is about the most difficult part. For the first year, I called my Industrial Hygienist and verified every single lab report to make sure I was reading them right. I still do but only if something showed up on a lab result that is not normally found in the air, also for all clearance samples of mold remediation jobs.

Are you sampling at multiple times throughout a day or other longer time period?

Many including C. Connell have found substantially varying spore counts in the same areas at different times......could lead to false negatives and/or positives.

[James E. Braun, CMI]

There are numerous ways if you do not know what you are doing and do not follow a standard testing protocol could you come up with a false negative or positive. Take the outside comparison counts that most home inspectors seem to have the most difficulty getting an accurate count. If preventative measures are done, the outside counts vary very little from day to day. I can even take an outside count in Jefferson City and my industrial Hygienist can take one in Springfield and our outside counts are not too far off, which I found was amazing. It is where you test and how you test is what gives you an accurate count. I seldom see an outside count out of a normal range. You cannot control how mold releases spores naturally. Just like radon or formaldehyde, mold is not an exact science.

[John Evans]

In reference to moisture meter readings in finished basements, beware that the wall construction methods at the exterior foundation will impact your meter readings. The common use of various vapor barriers including aluminum foil backed fiberglass will give inaccurate meter readings. I have encountered plastic sheeting attached to the back of the stud walls (set close to the foundation), some with and others without insulation. You may very well obtain normal readings at the drywall or paneled wall surfaces. But, if you access the plastic and peel it back, I can almost guarantee the presence of serious mold growth on the foundation walls. Through experience, I believe a very high percentage of sub grade finished basements have mold issues. This has become a high priority inspection process, sometimes pushing the non invasive limits. Bottom line, it is best to construct finished basement walls without any vaopor barrier. I now inform clients of the known hidden moisture issues with their finished basements.