Mold Worries: What Every Building Professional Should Know

June 5, 2006
Indoor mold growth exposes facilities managers to controversy and potential litigation

How new of a phenomenon is mold infestation? Mold has always been present in our outdoor and indoor environments; it caused primarily minor concerns and problems until 2001, when a legal case in Texas awarded a home- owner $32 million as a result of mold infestation due to construction defects. From 2000 to 2001, mold claims and lawsuits jumped from 1,000 to 12,000; just a year earlier, in 1999, there were only 12 mold claims/lawsuits heard.

What does all this mean to building owners and facilities managers? It means that indoor mold growth exposes you to controversy and potential litigation; it’s here to stay, especially with such a strong national focus on green buildings and more awareness of indoor environmental quality issues. With that said, it’s a good idea to be knowledgeable about indoor mold growth, the root causes of indoor mold growth, and the current guidelines and recommended work practices that should be used by mold remediators and individuals/companies performing mold investigations.

Interestingly, choosing the right remediation contractor could be the single most important decision that an owner or manager makes - one that could mean the difference between a successful clean-up or a negative outcome.

The Basic Facts
Mold is a fungus that grows on damp or decaying organic matter. It can survive for many years in dry or hot environments, needing only moisture and available organic matter in order to germinate (which it can do in as little as 4 to 12 hours). If it is undisturbed, the germinated matter can grow and spread in 1 or 2 days - especially when there is no sunlight, limited airflow, and minimal disruption. Common places for mold to grow are on window sills and door sills, walls, and ceilings, and underneath non-porous wallpaper. Food sources that can promote mold growth include unconfined cellulose (paper and dust), wood products, sheetrock, and carpet. In addition to water leaks contributing to its growth, the term “water” in relationship to mold can also refer to high relative humidity (usually higher than 60 percent).

In a healthy building, the types and concentrations of fungal species found in indoor air should be similar to those present in outdoor air, which indicates proper air circulation. Once excessive mold growth is found, it’s an indicator that there’s a moisture problem in the building’s envelope or systems; more than likely, it will get worse if it’s not corrected.

Health Issues and Indoor Mold Growth
Unlike asbestos and lead, the permissible levels of mold are neither clearly defined nor strictly regulated. Even at this point, there are no definitive guidelines for what constitutes a mold-infested building. Human response to mold varies widely, but no official medical relationship exists between exposure and human response. Two years ago, the Washington, D.C.-based National Academy of Sciences, Institute of Medicine found that damp, moldy buildings can make asthma worse and cause breathing problems in some people. However, it found no definitive causal relationship in the association between mold/moisture and other health complaints, such as fatigue, neuropsychiatric disorders, or other health problems. Often, physical symptoms can be related to common illnesses such as colds, influenza, and other allergies by a health professional.

Nonetheless, the National Academy of Sciences, Institute of Medicine says that, given how moisture problems commonly occur in buildings, mold should be removed as soon as possible when it is found. “[It] ... is a widespread problem that warrants action,” it notes. When human health is at risk, the failure to act can mean the enforcement of tough OSHA penalties for the building owner (example: the General Duty Clause, which is an obligation to protect workers from serious and recognized workplace hazards, even when there is no OSHA standard in place for the hazard).

The Best Approach to Elimination
The Environmental Protection Agency (EPA), Washington, D.C., maintains that “there is no practical way to eliminate all mold and mold spores in the indoor environment.” Still, every expert agrees on one thing: Prior to any mold remediation, the root cause must be identified and repaired. The EPA suggests a common-sense approach: “The way to control mold growth is to control moisture.”

The first step is often clear enough: Repair obvious leaks in roofs, windows, doors, and pipes. Poor ventilation or improper insulation often causes chronic moisture build-up. Implementation of preventive maintenance programs for mechanical systems is another recommendation to avoid moisture build-up in a building’s systems. During new construction or renovation, it’s essential that all building materials be kept dry and adequately ventilated before and after installation. Some newer building materials, like paperless wallboard and “breathable” wall insulation, have been specifically developed to resist moisture growth.

There are no current federal or state regulations for mold remediation methods. There are, however, several peer-reviewed and accepted standards of care that provide a good knowledge foundation for building owners and facilities managers when faced with mold contamination in buildings. These include:

  • Mold Remediation in Schools and Commercial Buildings - U.S. EPA, Washington, D.C.
  • Assessment & Remediation of Fungi in Indoor Environments - New York City Department of Health.
  • Bioaerosols: Assessment and Control - American Conference of Governmental Industrial Hygienists (ACGIH®), Cincinnati, OH.
  • Standard and Reference Guide for Professional Mold Remediation S520 - Institute of Inspection, Cleaning, and Restoration Certification (IICRC), Vancouver, WA.
  • Assessment, Cleaning, & Restoration for HVAC Systems/ACHR 2005 - National Air Duct Cleaners Association (NADCA), Washington, D.C.

The first step in every mold remediation project includes determination of the root cause of the mold growth. The next step is to delineate the order of magnitude of the mold growth via thorough visual examination. Since old growth may not always be visible, investigators may use instruments such as moisture meters, thermal imaging equipment, or borescope cameras to identify moisture in building materials or “hidden” mold growth within wall cavities, HVAC ducts, etc. Mold assessments and inspections should always include HVAC systems and their air-handler units, drain pans, coils, and ductwork. In addition, depending on the age of the building, the inspection should include sampling of building materials, such as ceiling tiles, drywall joint compound, and sheet floor for the presence of asbestos.

If mold is visible, this examination is usually sufficient. But, if no one is sure about what is causing the contamination, sampling may be part of the site evaluation to help locate the root cause of the mold growth. Sampling will identify some of the mold species and differentiate between mold, soot, and dirt.

If mold growth is localized and accessible, it may be possible to repair the source and clean the mold during routine maintenance. But, if no one is sure about what is causing the mold growth - or if it is widespread - it’s time to contact a qualified indoor environmental professional.

Some of the means, methods, and engineering controls that are used by mold remediation contractors to secure the environment and protect building occupants are similar to those used in asbestos abatement. This is because mold spores can travel on air currents and spread to other areas of the building if airborne particulates disturbed during the remediation process are not properly contained. These engineering controls may include:

  • HEPA-equipped air-filtration devices, which filter the air in the contaminated areas and assist in creating a negative air-pressure environment.
  • Poly sheeting affixed to walls, ceilings, and floors, when applicable, which seals the work areas from areas not being cleaned.
  • Air locks and decontamination chambers that allow for worker ingress and egress.
  • Detailed cleaning of all surfaces within the work area to ensure that no dust, dirt, or visible mold growth remains on any of the building materials.

Steps to Remediation Success
Unlike asbestos abatement, there are no defined regulations for “clearance levels” after a mold remediation project. How do you know if the mold remediation process has been successful? EPA guidelines indicate:

  1. The moisture source must be identified and fixed.
  2. Visible mold, mold-damaged materials, and moldy odors should not be present.
  3. After sampling, the kinds and concentrations of mold and mold spores in the building should be similar to those found outside.
  4. Shortly after remediation, the site should be revisited to make sure there are no signs of water damage or mold growth.
  5. Occupants should be able to return to the space without health complaints or physical symptoms.

The mold testing, assessment, and remediation industry continues to evolve. Just as in the early 1980s (when the asbestos abatement industry changed), there are minimal regulations and enforcement for these evolving remediation companies.

This has led to an influx of “boutique contractors” who may not possess the experience, expertise, properly trained labor force, or liability insurance that a building owner needs to help reduce liability. Texas and Louisiana are the only two states that now require mold-testing and remediation firms to be licensed. California, which passed the nation’s first mold legislation requirements, has a provision for “disclosure of mold” during real estate transactions. There are approximately 11 states with mold legislation pending, and there is proposed federal legislation (HR 1268): The United States Toxic Mold Safety and Protection Act.

The topic of indoor mold growth continues to be a controversial topic fueled by media hype and litigation. The best way for a building owner, property manager, or facilities engineer to minimize liability is to educate themselves on the topic. This is done by becoming familiar with the various industry peer-reviewed guidelines and recommendations referenced here, reading informative articles (such as this one), attending seminars or conferences presented by reputable organizations, and establishing reliable relationships with professionals in the industry who demonstrate that they have the expertise and experience to help solve a building owner’s problem when it comes to indoor mold growth.

Approaches to Effective Remediation Communication

According to the U.S. EPA, communication with occupants is essential for successful mold remediation. The status of the building investigation and remediation should be openly communicated, including information on any known or suspected health risks.

Small remediation efforts usually don’t require a formal communication process, but be sure to take concerns seriously and use common sense when deciding whether formal communications are required. Address the concerns of building occupants and communicate clearly as to what’s being done to address both the problem and possible health concerns.

Communication methods can include regular memos and/or meetings with occupants (with time allotted for questions and answers), depending on the scope of the remediation and the level of occupant interest. Tell the occupants about the size of the project, planned activities, and the remediation timetable. Send or post regular updates on the remediation progress, and send or post a final memo when the project is completed (or hold a final meeting). Try to resolve issues and concerns as they emerge: When building-wide communications are frequent and open, you’ll be able to direct more of your time toward resolving the problem (and less time to responding to concerns).

Communication is also important if occupants are relocated during remediation. The decision to relocate occupants should consider the size of the area affected, the extent and types of health effects exhibited by the occupants, and the potential health risks associated with debris and activities during the remediation project. When considering the issue of relocation, be sure to inquire about, accommodate, and plan for individuals with asthma, allergies, compromised immune systems, and other health-related concerns. Smooth the relocation process and give occupants an opportunity to participate in resolution of the problem by clearly explaining the disruption of the workplace and work schedules. Notify individuals of relocation efforts in advance, if possible.


Steven R. Silicato, REM, CIE, is a vice president at MARCOR Remediation Inc., a nationwide environmental services contractor located in Hunt Valley, MD. For additional information on mold remediation or MARCOR’s national mold seminars, go to (, call (877) 6-MARCOR, or send an e-mail to
([email protected]).

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