Sustainable By Design: Keeping Mold Away With Moisture Control

By Anne Cosgrove, TFM Managing Editor

Published in the March 2007 issue of Today’s Facility Manager

In recent years, the presence of mold in buildings has become an increasingly visible issue, from both health and legal perspectives. Average building occupants are now aware of the effect indoor air quality (IAQ) can have on their health, and as a result, facility managers are tasked with ensuring a safer environment in this regard. Identifying and eradicating mold friendly conditions should be the first step toward keeping occupants healthy and building assets intact.

While information on mold prevention and remediation is vast and varied in focus, a common thread throughout existing research is that moisture is a prime culprit in mold growth. In its literature on the topic, the U.S. EPA states, “molds can be found almost anywhere; they can grow on virtually any substance, providing moisture is present.” Meanwhile, OSHA acknowledges, “while it is impossible to eliminate all molds and mold spores, controlling moisture can control indoor mold growth.”

Formed in January 2006, the Responsible Solutions to Mold Coalition (RSMC) strives to serve as a clearinghouse for information on mold in commercial and residential structures. Launched through a grant from USG Corporation, a building materials manufacturer headquartered in Chicago, IL, RSMC members include 13 companies, associations, government, and academic organizations—among them the Association of Wall and Ceiling Industries International and the National Institute of Building Sciences. A main tenet of the coalition’s activities is that moisture control is key to mold prevention.

With this in mind, facility managers can now address the issue through a variety of moisture control measures. If a building was constructed with proper methods to keep moisture from infiltrating its structure, the facility is on the right track. These methods (which a qualified contractor should be able to perform) include identifying potential sources of moisture infiltration during design and pre-construction phases; sequencing work activities to minimize potential for moisture infiltration; employing active temperature and humidity controls when necessary to provide a suitable indoor work environment prior to permanent enclosure and conditioning of the building; and establishing a standard process to monitor humidity levels during construction activities prior to permanent conditioning.

But of course, not all buildings have been built to such standards. In these cases, concerned facility managers can assess the potential for mold growth in their buildings. From there, they can create a maintenance program to stay on top of threats to a healthy indoor environment.

To achieve this, a thorough inspection of the facility is in order. A facility manager may want to bring in an environmental consultant for this process; however, such an expert may be brought in after in-house staff members survey the building conditions.

Two main areas where mold growth often begins in a structure are the roof and the exterior walls. “Many problems start with a leaky roof,” says Paul Shipp, Ph.D., P.E., senior research associate with USG Corporation. “Inspection of exterior walls should include making sure flashings are draining properly and seals are in good condition. It’s also important to make sure drains are clear. Windows and pipe penetrations in walls are other areas to watch.”

Meanwhile, the selection of products designed to resist mold growth is increasing, and using these items is an effective step toward preventing the occurrence of mold. However, if mold resistant products are installed improperly or overall construction practices do not prevent moisture from penetrating the structure, the products can be expected to offer little protection from the eventual growth of mold.

“The first line of defense is proper design and construction practices,” says Shipp. “The second line of defense is to install mold resistant products. These products do not solve the problem, but they do play an important role. The main thing is moisture control.”

Aside from moisture penetration, high humidity levels in a building pose a threat. Research has found that it is beneficial to maintain relative humidity (RH) between 30% and 60%; mold needs at least 40% RH to grow. Therefore, controlling the humidity levels in a building is one of the keys to preventing mold.

To that end, measures recommended by RSMC include: reducing humidity by venting to the outdoors bathrooms, dryers, and other moisture generating sources (showers, stoves, and dishwashers); using air conditioners and dehumidifiers to remove moisture; in cooler, less humid environments, opening doors and windows to increase airflow whenever practical; reducing potential for condensation on cold surfaces by adding insulation around windows, piping, exterior walls, roofing, and floors; and avoiding the installation of carpet in areas where moisture is perpetually present.

Facility managers can track humidity levels with data loggers, which are mobile devices designed to measure a variety of interior conditions (including humidity). Depending on its capabilities, a data logger can sense and record over time the humidity levels in a room or a designated zone. This serves as a tool for facility managers to discover actual conditions and address them accordingly.

Left unchecked, mold can be a destructive force in a building. Costly materials can be damaged beyond repair, and if they can be repaired, removal and remediation present an expense. Additionally, mold poses a threat, whether real or perceived, to the health of building occupants. No matter where they are in the life cycle of their buildings, facility managers should take a measured and consistent approach to the issue of mold.

Information for this article was compiled through an interview with Shipp along with literature provided by the Responsible Solutions to Mold Coalition (