Hidden Mold

By Stephen Andrews

For five years, Carla successfully homeschooled her son. Over time, however, her bright and happy eleven year-old gradually developed health problems and his learning ability became impaired. Carla took her son to several doctors; his symptoms were treated but nothing seemed to help. Finally a doctor recommended she have her home air quality checked and inspected for mold.

My investigation showed no visible signs of mold growth. I checked the moisture in the floors on the main level, and found that it was elevated throughout the home. Since there were no visible signs of mold, air sampling for mold testing was recommended. Air samples were taken in the great room and dinning room for laboratory tests. The tests indicated elevated levels of Curvularia mold. I recommended to Carla that she go online and research the health effects of this mold. She found that her son’s symptoms paralleled those caused by Curvularia mold. She took the information to her son’s doctor and he agreed the mold could possibly be causing the illness.

Obviously, additional investigative work was necessary to determine the source of mold growth. Since the floors had elevated levels of moisture that’s where I began to look. I pulled the carpet back in the great room and discovered the concrete was covered with plywood. I moved to the dinning room and removed a small piece of hardwood and found that the concrete under the hardwood was also covered with plywood. The plywood was a greenish color and moisture in the plywood measured 22% – 24%, high enough to sustain mold growth.

The house was built on a monolithic concrete slab. Concrete had been acting like a sponge since the home was built, absorbing water in the ground and then transferring it to the plywood laid directly over the concrete slab. Together the moisture from the concrete and plywood laid on top of the concrete provided a food source for mold. With plenty of moisture and an unlimited food supply, the mold had grown to the point that the entire family had began to suffer from the effects.

When concrete is not poured over a vapor barrier, moisture in the concrete will usually measure much higher than 22% to 24%. This concrete slab probably had a vapor barrier between the ground and the concrete. However, the ground around the home was only two or three inches below floor slab, rather than the recommended six to eight inches. In addition, the ground around the home did not slope away from the building. (We recommend a per foot ground slope away from the home for a distance of not less than 10′). This allowed water and/or moisture levels to be held against the slab and wick into the concrete. During rains and lawn watering, water can even find its way in-between the vapor barrier and the floor slab.

The process used to remediate the home was extensive. All carpet, hardwood and plywood laid over the concrete had to be removed. Because moisture had even migrated from the floor slab into sections of the perimeter walls, some sheetrock on perimeter walls had to be removed. After remediation, the entire home and HVAC (heating ventilation air conditioning) system had to be cleaned and treated for mold.

I spoke with Carla about a year after the clean-up and her son’s health was much better. He no longer had any symptoms of illness, but she felt he had a slight attention problem that resulted from the long-term mold exposure.

It had been determined through clearance testing the remediation process was successful. The extensive reconstruction, however, did not go as well and after a few months Carla and her husband were forced to file a lawsuit against their contractor. This is an unfortunate twist in what otherwise would have been a happy ending to their story. Sadly, I have seen time and again the various ways mold wreaks havoc on individuals and families. Illness may not always be the worst effect, and the cost of the remediation is not always the biggest expense.. The long-term emotional and financial costs of mold can sometimes be enough to cause anxiety, destroy relationships, deplete savings, and even lead people to court before the matter is completely resolved.

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