Identify the Problem First

August 30, 2021 Bob Krell

By Jeffrey C. May–

I’ve worked with many clients who spent thousands of dollars unnecessarily.

In one situation, a woman was told that her basement was full of mold growth and that she should immediately move out of her house. She was given an estimate of about $3,000 to “de-mold” her basement. She moved into a hotel and called me for a second opinion. The mold growth was efflorescence: crystalized minerals from the foundation’s concrete.

When moisture migrates through concrete, it dissolves some of the minerals in the masonry that then crystalize on the inner surface of the concrete when the moisture evaporates into the air.

Efflorescence on a block wallMay Indoor Air Investigations LLC

To confirm that staining is efflorescence and not mold, you can scrape some of the material off the surface and put it in vinegar. If the material is efflorescence, it should dissolve, sometimes with bubbling.

The woman had to stop moisture from migrating into her foundation wall by taking better care of her gutter system: keeping the gutters and downspouts clean, and being sure that the downspouts emptied onto splash blocks, a drywell, or preferably into underground piping that emptied to daylight downhill from the house or at the edge of a deep landscape furrow. The house also had reverse grading (the ground sloped toward rather than away from the house), which can lead to moisture intrusion below-grade. If she had spent that $3,000 to have the foundation walls cleaned and sealed and had not done these corrections at the exterior, efflorescence would have again reappeared. And as time went on, the moisture in her basement could have raised the relative humidity, possibly leading to mold growth on cool surfaces. Luckily for her, mold growth had not yet occurred.

Aspergillus mold growth on a basement beamMay Indoor Air Investigations LLC

In another situation, a young couple bought a house, waiving the home inspection contingency to sweeten their offer in the face of fierce competition for the property. They were then told that leaking windows had resulted in extensive mold growth in wall cavities. They spent over $100,000 demolishing all the finished walls to open up wall cavities. There was some minor mold growth on the sheathing around the windows, but not because the windows were leaking. They send me some photographs of the opened-up wall cavities as well as the exterior of the windows. I could see that the window-cap flashings at the exterior were bent toward rather than away from the siding, so rainwater was flowing to the ends of the flashing and behind the trim and siding, resulting in some minor decay and mold growth. If they’d known about the flashings, they could have just opened up the wall cavities around the windows to check for mold growth and decay. And if they hadn’t known to correct the slope of the flashings, moisture would have continued to flow by capillary action behind the trim and siding where the incorrectly sloped flashings were located. 

Water flowed to the end of the miter joint and rotted the trim and framingMay Indoor Air Investigations LLC

In a third situation, a woman moved out of her new apartment after being there for only a week because she felt nauseated when she was there. Representatives from the gas company and fire department found no problem, but they never went into the basement below her apartment. It ended up that a gas pipe serving her cook stove had a loose fitting, and a large amount of gas was flowing out and up into her apartment through a space around the pipe.

Sometimes hiring an indoor air quality (IAQ) inspector can help you identify potential sources of IAQ problems. But you have to be sure the person is experienced and knowledgeable, not only about indoor air quality but also about building science.

How do you know you are hiring an IAQ inspector who is experienced and qualified? First, make sure that the person doesn’t have any relationships that could be conflicts of interest. Such relationships could include having partnerships with remediation companies or selling indoor air quality equipment such as dehumidifiers or air purifiers.

Read the full article in the July 2021 USA Edition of Healthy Indoors Magazine at:

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