Many types of mold can grow on water-damaged building materials. Penicillium, seen under a microscope top left, can grow on wood and other cellulose-rich materials, while Stachybotrys (bottom left) can thrive on wet fiberboard and paper. In the furnace room pictured above right, the black spots on the wall are Stachybotrys. (Photos courtesy of Sanit-Air.)
EDITOR’S NOTE:This is the second installment of a three-part series on mold and its relationship to HVACR systems. In this installment,The Newsexamines what some companies are recommending for the prevention and the remediation of mold.

It is the belief among most contractors that education — not overreaction — is the key to solving the current “hysteria” regarding mold.

“Until someone comes up with rules and guidelines pertaining to mold, we are just shooting in the dark,” said Carl Shirk of Champion Mechanical Services Inc., Siloam Springs, AR. “Changes in local building codes and inspections are going to have to be implemented and homeowners are going to have to be educated about the HVAC equipment they have installed in their homes.”

To illustrate his point, he said homeowners should have bathroom exhaust fans and all ductwork needs to be properly sealed. However, it is his belief that there is inadequate ventilation in many homes due, in part, to the end user not wanting to spend extra money in construction for proper installation — or, for taking the lowest bid on work.

“Listening to people at [a recent mold conference], many of whom were attorneys, are we really concerned about the mold and its damaging health effects, or are we more concerned with who we are going to sue if we have mold in our homes and businesses?” he asked.

It’s a question to ponder.

Stachybotrys growth is readily visible in this furnace cabinet.


In his bookThe Healthy House, John Bower states that mold requires five things to grow: food, air, a surface to grow on, a suitable temperature, and moisture.

“If you want to control mold, you must eliminate at least one of these five requirements,” writes Bower. “However, there is only one that can be reasonably controlled — moisture. A certain amount of moisture in the air is desirable for human health and comfort, but too much results in mold growth.”

Bruce Kester of Integrated Power Solutions (IPS), Austin, TX, agreed.

“We can’t stop flooding or burst pipes, but we can continuously maintain relative humidity,” he said, noting that IPS manufactures desiccant dehumidification products for use in buildings “that have significantly high levels of relative humidity.”

According to Kester and IPS, the highest relative humidity in a home is likely to occur when the air conditioner is not running. In hot and humid climates, the outdoor relative humidity can reach very near 100% on most nights, said Kester.

“During these periods, the materials in [the] home will absorb moisture from the humid air. If this moisture is not removed during the following day, the ‘water activity’ of the materials in [the] home can stay at or above 75% for extended periods,” said Kester.

Jerry Wolf of Air Purification Systems of Houston, TX, had some suggestions for preventing mold growth.

“Mold has to have moisture to live, so the most obvious things are to stop leaks or water intrusions of any kind,” he said. “Check roofs and flashings, seals around windows, commode seals, shower and tub grout, A/C pans, and drain lines. The list for water intrusion is endless and often overwhelming to the homeowner who is not a little bit handy. We have seen many cases where mold is literally growing on walls in a home because the humidity is too high.”

Water wicked up the wall in this bathroom while the homeowner was on vacation, allowing perfect conditions for mold growth.
Wolf knows that some homeowners decide to upgrade from a 3- or 4-ton A/C unit because it will “cool better.”

“They don’t realize that the system will cool the house so fast, it doesn’t run long enough to dehumidify the air in the house,” he said. “Or, maybe they put in a larger system but didn’t increase the filter size and now they are restricting the airflow and the coils ice up.”

Steve Bauman of Healthy Spaces, LLC, Austin, TX, said that proper building construction is a key to eliminating mold growth.

“Another location for the growth of bacteria, molds, and fungi are in the traditionally constructed wall systems of open cavity with two-by-four construction,” he said. “When these cavities are insulated, then sealed with a vapor barrier, and the siding is struck by the intense sun, it creates a scenario where the condensation can occur within the wall on the back side of the vapor barrier. This sets up the wall for extreme bacteria, molds, and fungi growth with the first intrusion of moisture.

“Solutions to this issue are to either provide adequate ventilation to the cavity, or to construct the exterior walls as solid walls, from solid, safe materials, such as autoclaved concrete or structural insulated panels [SIPs].”

Mike McGuiness of R.K. Occupational and Environmental, Phillipsburg, NJ, agreed.

“Moisture control, or lack thereof, in the design and construction of buildings is the primary culprit,” he said. “All buildings that were ever made or will be made will get wet to some extent. The best ones give water a way to get out again without impacting materials mold likes to digest. Wood is a great building material. I would rather see wood studs than metal studs any day of the week. Metal has no drying potential.”

News’ contractor consultant Roger Grochmal of Atlas Air/ClimateCare, Mississaugua, ON, does not consider himself a mold remediator. However, he does provide his customers with mold prevention measures.

“We will advise homeowners to try to solve mold source issues, such as wet basements, as a primary strategy and then perform mechanical retrofits, such as ventilation and dehumidification, to get the relative humidity below 50%,” said Grochmal. “We may then also use ultraviolet to ensure that any spores are cleaned up.”


McGuiness said learning about a number of moisture-control strategies is a key.

“Proper design and construction of buildings; appropriate moisture-control strategies; proper materials that are dry prior to installation; appropriate design for a given climate; proper orientation of air pressures in buildings; and the ability to use building science in construction efforts are steps to lessen mold growth,” said McGuiness.

So how can contractors and homeowners learn about some of the strategies that McGuiness listed? The answer: education.

“Several professional indoor air quality organizations offer professional development and certification programs,” said Connie Morbach of Sanit-Air Inc., Troy, MI. “One of the best that I have experienced that includes a broad spectrum of information with an emphasis on moisture control and HVAC systems is the Certified Indoor Environmentalist program offered through the Indoor Air Quality Association, Inc.”

Wolf said he thought he knew a lot about mold, but had a humbling experience.

“I feel that anyone who does mold remediation should go to an accredited class and be taught by qualified instructors about the true facts of mold and how to safely and properly handle remediation,” he said. “They should then be required to pass a certification test before they do any remediation.

“I’ve been in IAQ for almost 23 years and last year I went to an in-depth and thorough class and got certified. I thought I knew a lot about mold before going to this class but soon found out I was really a novice.”

McGuiness had a specific recommendation.

“Attend classes at quality training centers,” he said, having praise for the Mid-Atlantic Environ-mental Hygiene Resource Center (MEHRC) in Philadelphia. “It is the number one IAQ training facility in the country. They offer courses on all these topics.

“I would caution that this type of work requires significant experience and training to do well. It is not something you can just take a course and be proficient at.”

Bob Baker of BBJ Environ-mental Solutions, Inc., Tampa, FL added, “Start with their suppliers. Since there has not been very much in the way of good research, information provided by suppliers is at least as good as any other around and at least it is free.

“My experience with most contractors is that they have enough good sense to sort out the information that is useful from the kind that is not.”

Another News’ contractor consultant, Scott Getzschman of Getzschman Heating & Sheet Metal/ Service Experts, Fremont, NE, sees a future in remediation for HVACR contractors — provided they become properly trained and educated on the subject.

“You have to be able to identify all of the sources for mold growth, because you could solve it in the HVAC system but still have it in a basement due to a leaky foundation,” he said. “The liability could be great, so we are gathering information and training at the same time.”

For more information regarding the Indoor Air Quality Association Inc., go to (website).

Next week, Part 3 of the series will examine how the initiative to inform and aid consumers could become a new profit center for HVACR contractors.

Publication date: 07/01/2002