Bau-Biologie: Humidity, Moisture, and Mold

[This article continues the results of my Bau-Biologie Home Inspection.]

Humidity is an important factor for indoor air quality that most people don't pay much attention to. In Home Safe Home, I included a short section on Humidity and mentioned "High relative humidity, over 50 percent, encourages biological agents--such as bacteria and viruses, house-dust mites, and molds--to grow and be released into the air." Then I went on to discuss how humidifiers and de-humidifiers can be used to control humidity both for comfort and to reduce biological agents.

But there is much more to know. As with toxic chemicals, it's better to reduce humidity at it's source rather than use a machine to try to correct an unbalanced environment.

At my house, I had conditions both outside and inside that were affecting the humidity in my home, which in turn led to a mold problem that is requiring some major fixing.

My Bau-Biologie Home Inspection came with an excellent report that gave all the test results, along with explanations of the range of measurements that are ideal, weak, strong, and extreme.

The inspectors tested for humidity outdoors, and in my kitchen, living room, bedroom, and bathroom using a Extech Psycrometer RH300.

Outdoors that day the humidity was 67%. Outdoors, it is not an issue because we can't control outdoor humidity. If it were indoors, however, 67% would be considered "strong--unacceptable biological risk, remediation should be done as soon as possible". And this was on a clear winter day when we Floridians are rejoicing that it is "not humid"! In the summer, the humidity is much worse! But during the summer months, the humidity indoors is lowered by the air conditioner. Because it doesn't feel humid to me in the winter, it never occurred to me that the humidity could still be too high.

Both the kitchen and bathroom had even higher relative humidity levels, though still in the strong zone. This could be expected since those are the two rooms where water is used, but further inspection revealed problem areas that could be fixed to reduce the humidity in those rooms.

They also tested various materials for "relative wetness" using a Delmhorst BD-2100 MoistureCheck meter. Excessive levels of moisture (over 200%!) were found in two locations in the bathroom. A problem was beginning to reveal itself...

In a visual inspection of the crawlspace, the inspectors found visible mold, so a sample was taken for laboratory analysis. The test results showed the presence of Aspergillus/Penicillium, Curvularia and Scopulariopsis. The presence of these molds "is really troubling as these have been known to trigger respiratory problems and other, sometimes severe, health symptoms". These molds require high moisture requirements for growth.

Because of the high moisture content, there was some concern--before the lab results came back--that there might be Stachybotrys mold present. I knew about Stachybotrys because it made the news in 1994 when it was associated with acute bleeding of the lungs in a cluster of infants in Cleveland, Ohio. One infant died. Though I wrote in Home Safe Home, "Constant moisture is required for it to grow, so don't be concerned about it unless you have water damage, water leaks, condensation, water infiltration, or flooding," to me this meant if your house was flooded, not that you have a leak in the bathroom.

Though I was fortunate to not have Stachybotrys in my house, my house apparently does have the conditions in which it can grow. In both this house and in my previous house in California, the bathrooms were not installed correctly and there were moisture leaks sufficient to saturate the flooring under the tub. Because these leaks were hidden, we could not see the damage that was occurring. In California, we finally addressed the problem when the tiles started falling off the wall and we found the wood behind them was full of dry rot. Here, the paint is peeling off the wall near the leak. So this is something to watch out for in any home.

For us, this discovery of mold was a major finding. Apparently there was enough mold to contribute to health problems. Because the mold wasn't visible, we probably would not have found it on our own.

The Baubiologie Home Inspection report recommended that we have an inspection by a certified mold remediation contractor to determine the extent of the mold problem and properly remove it. "Properly remove it" in our case meant having our entire bathroom ripped out by a professional mold remediation contractor because the mold was in the floor. And then we would need to entirely replace the bathroom with a new one. This was a bit of a shock so it took us about a month before we made that call. Meanwhile, the smell of mold was getting stronger and stronger.

coming on March 7...our professional mold remediation...

SOME USEFUL LINKS ABOUT MOLD

Doctor Fungus: Non-Technical Introduction to the World of Fungi and Mycology
A basic introduction to what mold is, how it functions as a living organism, and all kinds of interesting data about the importance of mold to life. You can also look up almost any mold and find out everything you could ever want to know about it, including health effects.

US Environmental Protection Agency: Indoor Air - Mold
The "start" page for all the EPA mold resources, including an introduction to molds, basic mold cleanup, what you should know about mold, floods and flooding, health and mold, homes and mold, indoor air regulations and mold, and other mold-related resources and links.

National Association of Home Builders Mold Resource Center
Mold testing and risk assessment, prevention and control, and clean-up tips.