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Treat the Cause, Not the Symptoms


By Robert J. Kobet, AIA

In 1981, I was very fortunate to be asked to design a home for Dr. Roy E. Kerry, a physician who specialized in treating patients with multiple chemical sensitivities.

Dr. Kerry’s wife was exquisitely sensitive to a number of environmental insults and bravely served, with careful supervision, as the test subject for the materials that would eventually comprise the first home in the country designed as both a healthy home and chemical-free oasis where he could meet with his most sensitive patients.

Mold on wall
© / Urban78

I regularly read articles that do a great job of describing how to remove mold from interior surfaces without any reference about how to keep it from occurring to begin with. Understanding material science is central to this effort.

Sick building syndrome had recently emerged as a collision between efforts to make buildings tighter and more energy efficient; a building materials market almost devoid of suitable, tested and environmentally acceptable building materials; and HVAC design methodology that did not have the advantage of commonly used computer aided systems optimization.

Healing with Design

One of Dr. Kerry’s major motivations was the fact he could not fully cure or rehabilitate his patients knowing they would return to a home, school or workplace that was not environmentally benign. And, even the most conscientious, diligent cleaning regimens would not suffice if the environmental irritants targeted were not permanently removed. This included, but was not limited to, volatile organic compounds (VOCs) and micro-flora, commonly know as mold or mildew. 

For over a decade we worked together with his physician colleagues to educate patients about how to deal with why incitants, or causal agents, of environmental illness occur and how to remedy conditions in the field that allow them to propagate.

The goal was to create built environments that served as an oasis for recuperation and healing. What resulted is a merger of building forensics and material science that formed the basis of the first continuing education units I authored on allergen-free, non-toxic design for the American Society of Interior Designers in 1989, and the Mold Prevention credit found in the initial LEED for Schools Reference manual.

Today, we call it healthy building: the integration of optimized building envelopes, building systems, materials and maintenance using human ecology as a design determinant.

Clearly, the proliferation of green building rating systems; increased awareness about the impact of materials on interior air quality; and evolving regulations that collectively advocate for healthy buildings have done much to improve the built environment when they are used as design drivers.

volunteering post Katrina
Courtesy of author

I volunteered in schools ruined by water and mold following Hurricane Katrina.

Still, I regularly read articles, newsletters and blogs that do a great job of describing how to remove mold from interior surfaces without any reference about how to keep it from occurring to begin with. Understanding material science is central to this effort.

Understanding Mold

Ecologically, more than 100,000 types of mold serve as decomposers of organic material such as wood, plants and animals, according to an article by Dr. Nathan Yost of the Building Sciences Corporation. Without them we would be inundated by our waste products that otherwise would not be removed from the environment. Mold spores enter buildings through the air, on people, pets and anything brought into a building. Most people tolerate exposure to moderate levels of many different molds without adverse health effects.

There are only a few molds that can cause infection in healthy humans. However, some can produce powerful chemicals called “mycotoxins” that can induce serious illness in animals and people. Others can only impact people with compromised immune systems. Allergy symptoms and asthma are the most common reactions in susceptible people.

“Mold requires nutrients, water, oxygen and favorable temperatures to grow,” Dr. Yost writes. If any of these elements do not exist, mold will not be present.

“Nutrients for mold are present in dead organic material such as wood, paper or fabrics; mold can also derive nutrients from some synthetic products such as paints and adhesives,” he adds. Garbage or food left untended over time will quickly generate mold growth.

Water Intrusion

Water is generally present in architecture due to:

  • Catastrophic weather events and subsequent inundation of structures;
  • Ongoing weather intrusion due to poor building envelope design or maintenance;
  • Significant one time or persistent leaks in building systems that contain water;
  • Elevated humidity due to excessive moisture generation in such places as kitchens, baths, laundries, locker rooms, crawl spaces, etc., and / or attendant poor ventilation or dehumidifying of those spaces; and
  • Condensation due to low surface temperatures on interior materials that are “chilled,” often as a consequence of localized cold air infiltration.           

Mold’s Presence

Mold generally likes the same conditions we do, which is why it is quite common in the built environment. Mold can live with moisture in any form, and some mold species can obtain that moisture from moist air when the relative humidity is above 70 percent, Dr. Yost indicates. 

Many molds thrive at normal indoor temperatures; few molds are able to grow below 40 degrees Fahrenheit or above 100 degrees F, according to Dr. Yost. Outside this range molds may remain dormant or inactive; they may begin to grow again when the temperature is more favorable. Temperatures well above 100 degrees F will kill mold and mold spores, but the exact temperature required to kill specific species is not well known.

Because it is used extensively in construction and very susceptible to moisture, paper-faced gypsum board is often the host for mold growth. Paper is largely pre-digested so it is easy for mold to get the nutrients it needs. Many species of mold grow on paper-faced gypsum board if sufficient moisture in any form is present. Specially formulated cement board, mortar or non-paper faced gypsum can be safely used in these damp areas because these products do not contain nutrients to support mold growth or because they have been treated to resist mold.

It must be noted that some occupants who are chemically sensitive may react to the chemical treatments used to resist mold. In all cases materials should carry third party testing to verify it is benign.


No amount of cleaning can deter mold from returning to conditions where moisture is allowed to persist.

Conversely, where there is potential for mold, ceramic tile, enamel, vitreous china, metals, and other non-fibrous, non-hygroscopic materials work well for two reasons. First, they inherently do not provide a nutrient source (although nutrients can reside on them), and second, they can withstand repeated vigorous cleanings with green cleaning products without breaking down.

Quality building materials are a critical component of any integrated design effort to minimize environmental insults. However, even the best selection of materials can be compromised if such things as ground water intrusion, excess humidity, poor space conditioning or chronic maintenance shortcomings aren’t corrected first. Healthy buildings and superior indoor air quality efforts should always be based on eliminating the causes of mold, not simply treating the symptoms.  


Robert J. Kobet, AIA

Robert J. Kobet has enjoyed a dual career as an architect and educator. For more than 35 years Kobet practiced internationally in the fields of sustainable design and development, high-performance green buildings, LEED consulting and environmental education. He is currently enjoying a working retirement that includes a position as adjunct faculty in the Kent State University College of Architecture and Environmental Design where he teaches a variety of courses based on sustainability and regenerative environmental stewardship. For more about Kobet, please visit



Tagged categories: American Institute of Architects (AIA); Architects; Building design; Construction; Good Technical Practice; Green building; LEED; Schools; The Kobet Collaborative; Architecture; Building Envelope; Building envelope; Building interiors; Design; Humidity and moisture; Moisture detection; Moisture management; water damage

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