Mark Meshulam is an expert witness and consultant for leaks and mold in walls.
To many building owners, the thought of mold in their walls invokes images of coughing, mold-allergic occupants and plummeting property values. Indeed, these scary visions can become realities if the problem goes unmanaged. But fear will not solve the problem of mold in walls. Educated action will.

Mold is a category of living organisms related to mushrooms and yeasts. Molds are all around us, in the air we breathe, in the soil, in our foods (soy sauce, beer) and even in our medicine (Penicillin). When molds find a home in our walls and ceilings, they produce discoloration, damage to materials and an unpleasant, pervasive musty smell.
good mold bad mold in walls
The presence of mold in walls is a symptom of an equally destructive problem, excessive moisture. This moisture can come from leaking plumbing, seeping foundations, over-eager humidifiers and leaks in elements of the building exterior. Leaks through the roof, walls, flashings or windows can bring about major volumes of water penetration, extensive water damage and wildly spreading colonies of mold in walls and ceilings.

Mold remediation experts agree that there is no point in remediating the problem of mold in walls unless the water problem is first controlled. Even with the best mold remediation, the mold will return if the wet conditions persist.

Yet, when roofs, flashings, walls and windows leak, it’s not easy to determine the exact cause. The points of water entry at the exterior of the building envelope can be very different from the places where the presence of water is seen on the inside.

Your Chicago Window Expert has heard the phrase “the windows are leaking”, when in fact the leaks entered through some other part of the wall construction, more times than he has fingers and toes (he has the average amount). As a window contractor, he has been frustrated by such comments to the extent that a particular one of those fingers wanted to respond.

However, as a “building envelope consultant”, he is happy to find ways to bring his background in testing to the benefit of owners with sick and leaking buildings. It is only through testing that destructive water paths can be discovered. It is also through testing that remedial measures can be validated. When the water is stopped, the problem of mold in walls can then be eliminated. Having said that, he is now going to stop writing in the third person.

The discovery of mold in walls and ceilings

Mold doesn’t suddenly spread like a bomb blast. Rather, it grows slowly and gains until a time in which someone finally notices it. The process reminds me of when I first discovered that I needed glasses. For a year or more my eyesight slowly got worse, but because the deterioration was slow, I didn’t realize it.

My first windows
My first windows

Finally, a teacher noticed I was squinting in order to see the blackboard (they still use blackboards, don’t they?). She took me aside and told me she thought I needed to get my eyes checked. I was shocked that I didn’t notice such an obvious and important thing. I was blind to my blindness! Similarly, we become immune to the musty smell of mold in walls until a fresh-nosed visitor starts twitching and gagging.

Occupants in buildings with mold in walls sometimes experience that same type of surprise. The smell may have slowly gotten worse, but the occupants became used to the smell. Or the spot on the wall may have grown very slowly over time. Once the discovery is made, however, the mold infection may seem to spread like a bomb blast. People start chiming in about how they smelled that smell but didn’t mention it out of politeness. When walls are opened to discover the extent of the problem, mold spores are released into the air, making a much more noticeable smell very quickly. Soon, someone will call a mold inspection & testing agency.

The mold inspector collects data and samples from the site, and returns later with a report. Sometimes the report can be daunting:

Sample test for mold in walls report
Sample mold test report


The report addresses the fact that molds are everywhere, by comparing the mold levels inside the living space with molds outside (the “outdoor control”). The identification of the specific mold species helps the next professional, the mold remediation company, to know what antiseptic to use to kill the bad mold.

Removal of mold-infected materials
Removal of mold-infected materials

When mold remediation professionals come to a site to perform mold remediation, they often create an air barrier, a full height partition of sheet plastic to keep the mold in a confined space. Then, with mold-filtration machines circulating the air, workmen remove and dispose of wet or infected materials, and throw them away in double bags, taken to specially assigned waste facilities.

Then, the mold remediation guys apply an antiseptic spray followed by mold-resistant paint. They leave the blowers running until the moisture and mold levels become into the appropriate range, then their job is over. Others are left to restore the walls.

What’s wrong with this picture?

In the cases where the water source is not obvious, such as through the exterior walls, who is diagnosing the leak? Who is prescribing a fix? Who is validating that the repair worked?

In the cases where design deficiencies (I am too polite to say that the architect or contractor may have screwed up) are the root cause, who will analyze that deficiency and design a work-around? And again, who will validate that the repair will actually work?

Now, instead of being discouraged that people blame windows for wall leaks, I am encouraged because this misconception has brought me a series of clients who are in need of my skills, and has helped identify a gaping hole in the marketplace. The harmonic convergence that has occurred is that the methods and technologies we regularly employ in the testing and quality assurance of windows, can be readily adapted to tracking the source of leaks in buildings and mold in walls, validating the results of repair.

Mark Meshulam, Chicago Window Expert, is now a moldy-oldy
Mark Meshulam, Chicago Window Expert, is now a moldy-oldy

Looking for help finding the source of your mold in walls?

2 thoughts on “Leaks and Mold in Walls: the dirty little secret”

  1. sir or madam
    i tried to check w/BBB on chicago window expert/builders architectural inc in deerfield il.
    nothing comes up? I have a leak that is damaging the whole wide of my home. I had a new roof put in. shortly after i found water in my fire place. have invested 1200 in chimney repair. last week found a window on that side of the house soaked window on right of chimney. then went up in attic and found water on left side of chimney under attic vent. Roofer had come back after first discovering water in fireplace. he said flashing around chimney couldn’t be any tighter.had mason come and repair some grout (cement) that looked as if it needed replacing. he told me if ther is moss on siding there may be moisture behind it. next day found soaked window. day later went up in attic and found went plywood under vent in attic. No one seems to be able to find out where leak is coming from. I’m a person of modest means and have no idea where to go with this. who to get to find leak or leaks. I don’t want my home to be mold city. HELP
    thanks Freddy

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