NEW ORLEANS, LA — Joe Lstiburek doesn’t pull any punches. He doesn’t shy away from blunt remarks about the topic of mold and indoor air quality (IAQ). Lstiburek, Ph.D., P.E., is a principal with Building Sciences Corp., a Boston consulting firm. He was also a featured speaker at the annual meeting of The Unified Group.

The organization, made up of 30 independent HVACR contractors, recently held its “Annual Meeting and Service Manager’s Forum” at the Wyndham Canal Place Hotel in New Orleans.

Lstiburek broached the discussion about the current mold situation this way: “A lot of people like to dismiss this as the rantings of an irresponsible press and scumbag attorneys.

“Isn’t it strange that we have less water in our buildings but we have more water problems? Water hangs around longer in building materials today.”

Lstiburek emphasized that the problem with mold hinges on water — and the entire construction process is a wet process. “Concrete is basically 50% water,” he noted.

He also points to the abundance of insulation in buildings. “Insulation is designed to stop energy exchange, which is necessary to speed up the drying process. We have reduced the interior permeability dramatically.”

Lstiburek said efforts to reduce mold growth should be focused on drying buildings rather than preventing them from getting wet. He added that the “dwell time” for moisture in buildings has gone up while drying capacity has gone down, citing air conditioning as a contributor to longer dwell time.

“Any building that is air conditioned must not have a vapor barrier on the inside, but we regulate to ensure that moisture happens,” he said. “Until we disconnect the mechanical system from the building envelope, we will have IAQ problems.”


Lstiburek said there are five basic steps to dealing with the mold “problem”:

1. Find water.

2. Find mold.

3. Clean up mold.

4. Dry the building.

5. Make sure it doesn’t happen again.

“The water is going to tell you where the mold is — simple as that,” he stated.

Lstiburek said it is difficult to diagnose an air sample if the contents of the walls and ceilings are unknown. He said there are several factors to consider during diagnosis, including:

  • Heat flow is from warm to cold.

  • Moisture flow is from warm to cold.

  • Moisture flow is from more to less.

  • Air flows from a higher pressure to a lower pressure.

  • Gravity always exerts a downward force.

    “If you understand this, you can diagnose a building,” he said.

    In order to have a problem in a building, Lstiburek said the following “four P’s” must be present:

    1. People;

    2. Pollutants (including water, heat, and ultraviolet light);

    3. Path (connecting people to pollutant); and

    4. Pressure.

    Lstiburek recalled for the audience his experience testing a building in Washington DC — the James Madison Building, which is located directly across from the U.S. Capitol Building. The James Madison Building was having a negative pressure problem. Lstiburek found that the built-in loading dock of the building was acting as a fresh air intake for the entire building. The negative pressure in the building was also drawing air from the Capitol Building through an underground tunnel that connected both buildings. The problem was solved in part by installing revolving doors in the tunnel. Lstiburek was able to make other changes to the building design in order to create a positive pressure situation.

    “It is simple — negative sucks, positive blows,” he said.


    “We have no idea what the relationship between mold and health is,” Lstiburek stated. “There isn’t a doctor in the world who can say, ‘You are sick because of exposure to mold.’”

    “I believe there is a relationship, but I just don’t know what it is.”

    He also said that the mere presence of mold in a building does not necessarily mean that people will react to it, adding, “Everything is toxic. It depends on the dose.

    “Things are settling down as the good information gets out there. We’ve made it through asbestos, radon, and leaded paint.”

    Lstiburek said that if contractors are interested in mold testing and remediation, they should be “smarter than their competition.”

    “If you are installing, you are a commodity,” he concluded. “If you are diagnosing and fixing, you will be paid to use your brain.”

    Publication date: 12/16/2002