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Facilities At Risk

By Daniel P. Mahoney, CIH, CSP XL Environmental, Inc.

Claims related to mold exposure and remediation have mushroomed. With this rise in claims, it has never been more imperative for facility professionals to learn about the risks of mold, the ways its growth can be mitigated, and the best methods for quick and cost effective remediation.

Uncontrolled growth of mold indoors can result in property damage, impair the use of buildings, and potentially expose occupants to unhealthy conditions. On top of that, mold remediation can be costly. In El Paso, TX, for instance, a school district spent $4.2 million on mold related renovations to 14 schools.

The Usual Suspects

In controlling a facility's mold exposure, it's important to recognize the conditions that promote mold growth-mainly moisture. For that reason, preventing water from entering the building and controlling the relative humidity inside a facility are top priorities in mold prevention. Roof leaks, plumbing leaks, or sewer back-ups that allow water into a building are some of the triggering events that lead to mold problems.

Buildings that have a history of water leaks present a higher degree of mold risk. Persistent minor leaks that are not resolved, such as small roof leaks or leaks around window frames, are commonly associated with uncontrolled mold growth. More extensive leaks that take longer than two days to clean up and to dehumidify the area are also high risk indicators.

If porous or semi-porous materials become wet and remain within the building, these materials are likely to harbor mold growth. Buildings constructed of biodegradable materials such as wood sided frame structures are also likely to harbor biological activity as the building envelope and structure members can absorb moisture. Facilities, therefore, need to adopt tight maintenance regimes for building systems and conduct regular inspections to identify and stop leaks throughout the facility.

The Unusual Suspects

Preventive maintenance of HVAC, plumbing, and other building systems can reduce the potential for mold growth. Facilities that disregard maintenance of filters and condensate drains are at increased risk.

HVAC systems that cycle off during non-occupancy hours to save energy can result in fluctuations in temperature and humidity conditions, which may promote mold growth. Undersized and oversized HVAC systems are also associated with inadequate moisture control.

Aside from regular building systems and leaks, water intrusion can also occur during construction and renovations. Thorough planning prior to construction activities is critical to prevent moisture from entering the structure.

Consideration should be given to protecting construction materials from precipitation once they are delivered to the site. Additionally, building openings should be protected when possible to reduce the amount of moisture that enters the interior of the structure during the construction process.

Humidity Controls

Local weather conditions also influence the degree of mold risk. Buildings located in areas with high precipitation or persistently high humidity must defend against outdoor conditions. In order to control indoor mold growth, the relative humidity should be kept below 60%. Facilities located within flood plain areas may also need special design considerations such as sump pumps, moisture barriers, and exterior grading to prevent rising surface and ground water from entering the structure. Basements and crawlspaces persistently high in humidity can damage stored contents and building structure integrity. Interior moisture sources can also contribute to the humidity levels within the structure. Indoor pools, spas, laundries, or other wet processes add a significant moisture load. HVAC systems need to be designed to handle the excess moisture load in order to remove the moisture from the structure.

Cleanup

Remedial techniques vary for different surfaces and structures. These methods include scraping, sanding, cleaning, painting, or a combination of these on immovable woodwork. If mold has penetrated the woodwork and can be removed, it should be. When metal structures are involved (such as sheet metal ductwork), they can often be wiped clean. If lined ductwork is mold contaminated, the fiberglass liner may have to be removed and the sheet metal scoured with a brush and a cleaning solution.

The New York City Department of Health has published Guidelines On Assessment And Remediation Of Fungi In Indoor Environments. The Guidelines help to define the potential degree of risk and provide suggested cleanup methods based on the extent of damage and the building materials involved. These guidelines outline general abatement strategies based on the square footage of the moldy area.

The levels are defined as follows:

• Level I: Small Isolated Areas (10 square feet or less)-e.g., ceiling tiles, small areas on walls;
• Level II: Mid-Sized Isolated Areas (10 to 30 square feet)-e.g., individual wallboard panels;
• Level III: Large Isolated Areas (30 to 100 square feet)-e.g., several wallboard panels;
• Level IV: Extensive Contamination (greater than 100 contiguous square feet in an area); and
• Level V: Remediation of HVAC Systems.

Sometimes It Comes Back

If mold growth has been a problem in the past, or if remediation has occurred, the cleanup methods used can be an indication of the probability of any type of recurrence. If cleanup was slow to occur after the leak (more than two days), and if it was limited to air drying and vacuuming up water, there may be the chance the cleanup was inadequate. The New York City Department of Health Guidelines, citing ASHRAE 55-1992, suggest that:

In all situations, the underlying cause of water accumulation must be rectified or fungal growth will recur. Any initial water infiltration should be stopped and cleaned immediately. An immediate response (within 24 to 48 hours) and thorough cleanup, drying, and/or removal of water damaged materials will prevent or limit mold growth. If the source of water is elevated humidity, relative humidity should be maintained at relatively low levels. Emphasis should be on ensuring proper repairs of the building infrastructure, so water damage and moisture buildup do not recur (Remediation, Guidelines On And Remediation Of Fungi In Indoor Environments, Section 3, New York City Department of Health).

Naturally, proactive treatment is recommended for mold related issues and claims, but few facility professionals have been proactive about adopting this behavior. Still, informed facility professionals should do everything possible to address typical indoor air issues, including mold growth, before they become serious problems.