Mold can be found everywhere we work, live, and play. Whether indoors or outdoors, floating in the air or stuck to surfaces of all sizes and shapes, mold is always present in our environment. In most cases, mold isn’t a problem for us or the places it lives in (the production of some life-saving foods, beer, and medicines needs mold). But mold has a particular preference for the materials we use in the construction of our buildings and the conditions in which we use them. This becomes a problem when mold threatens the safety and performance of building materials, leading to potential cost overruns, scheduling problems, and delivery delays. In other words, unwanted overtime and potential backlash from architects, engineers, owners and contractors who no longer have a well-defined high-quality building product but a compromised one. This article discusses ways to identify the conditions that support mold growth and how to prevent mold from affecting the quality and suitability of building materials. What is mold? Mold is an organism in the diverse life kingdom of fungi, which includes mushrooms, molds, and mildew. In nature, mold is one of the largest recyclers of organic matter and plays an important role in the breakdown of plants, leaves and wood. Mold reproduces by microscopic spores that are easily transmitted elsewhere in the air, by physical disturbances, even by attaching our clothes to rides. Most mold species can produce spores into the millions, even billions under limited, common growing conditions. Mold spores are invisible to the naked eye, except when they thrive in colonies and grow visible masses of spores pigmented in yellow, green, black, orange and a host of other colors. The mysterious green mold on bread in the kitchen started from mold spores that fell on the bread and grew. Mold needs four things to grow. But the most important is moisture – no dampness and no mold. Mold also needs a food source, oxygen, and a temperature of roughly 32 to 140 degrees Fahrenheit. The ideal temperature for mold growth is between 70 and 85 degrees Fahrenheit. These needs are generally met in an endless variety of situations where we place building materials indoors and out. Mold and Building Materials Mold thrives by consuming organic matter and growing under the normal conditions found practically everywhere that building materials are found. He has a strong appetite for organic materials, especially cellulose in wood and wood products. Cellulose is the main material in plant cell walls and a component of wood and wood-based products, which is found on every building site and in practically every structure around the world in one form or another. The fibers in wood contain the sugars, starches, and proteins that mold needs to live. When the four basic growing conditions are present, mold will thrive while consuming its food source. Once mold starts eating, it can be a tough person to walk away from the dinner table. In general, the more a wood product is processed, the more it will prefer mold as a food source. Materials made from shredded wood are more likely to contain and preserve mold than solid wood. The finer structure (eg, chipped) of today’s wood-derived building material provides mold with an excellent food source. For example, mold prefers wet paper over wet wood and oriented strand board (OSB) over wood. Mold can colonize even inorganic materials such as metal, concrete, glass, or painted surfaces when a thin layer of organic nutrients is present. Recognizing a Mold “Problem” Problems associated with mold on building materials include discoloration from mold spots and rot that erodes the fit of the material. Even small amounts of mold, appearing only as innocent-looking surface dust, can lead to outright rejection of the material and the need for laborious cleaning or replacement. More time in an environment conducive to mold (such as moisture, food, temperature, and oxygen) increases the chances of material damage from mold or moisture. Depending on conditions, this ranges from just a few days for paper-backed drywall to a week or two for plywood, for example. Early detection and prompt troubleshooting of moisture problems is a way to prevent mold from becoming a serious setback. The two main tools for detecting mold are our eyes and nose (despite our unusual techniques). If you can clearly see or smell mold, there is likely a mold problem. There is generally no need for testing, microscopic analysis, air sampling, and other similar examination procedures. The visible presence of mold or its unpleasant odor is sufficient to warrant further examination of the moisture problem and the cleaning or replacement of building materials. A rudimentary, “eye-and-nose” approach to mold detection is reassuring when one considers that there is no industry standard for determining whether a mold problem exists (for example, the number of spores on a square millimeter of drywall). The US Environmental Protection Agency (EPA), for example, does not regulate the amounts of mold or mold spores in indoor air. Likewise, there are no health standards that determine whether exposure levels to mold are too high. Let your eyes and nose be the tools to spot a mold problem before it gets out of hand. Control moisture to prevent mold. Oxygen, appropriate temperatures, and food sources are ubiquitous in building materials, and controlling these conditions is not critical to preventing mold. However, controlling moisture is the most effective way to keep building materials mold-free. Determining and controlling humidity by monitoring and evaluating materials and the environment. Look for signs of moisture intrusion, mold resistance, and high relative humidity levels. Relative humidity, which is basically the moisture in the air, favors mold growth above 50 percent and amplifies mold growth as the humidity level increases. Check the relative humidity at different times of the day as it may fluctuate. Consider multiple relative humidity readings above 55 percent that indicate a potential humidity problem that needs to be resolved. It is important to find and correct the problem of moisture or mold, and the possibility that the material will still become unsuitable will remain. A portable or wall-mounted hygrometer can provide a reliable reading of relative humidity. These tools are available for purchase online and in home supply stores. Indoors, relative humidity can be controlled using air systems, dehumidifiers, and other mechanical means to physically cut out moisture-laden air. Large building envelope leaks and water leakage problems such as leaky foundations and burst pipes need prompt corrective action. There is a more significant challenge in controlling relative humidity outdoors or in non-enclosed spaces. However, it usually involves solving a moisture related issue such as unexpected water leakage to the storage area and then allowing the material to dry and remain as well. Spread the word, so mold doesn’t think of ways to reduce the risk of mold damage before it happens and also let buyers, distributors, and contractors know. One way to reduce mold risk is to assess the conditions in which the material is transported, stored, and used. Condition assessment conducted along the supply chain and throughout the product life cycle reduces the chances of material rotting. The goal of the assessment is to monitor, evaluate, and correct potential conditions that are conducive to mold growth. Start by looking at the transportation and delivery conditions for building materials. Monitor moisture intrusion and elevated relative humidity. Where moisture is present, the interior of trucks, containers, boxes and cardboard packaging is a suitable place for the mould. Then consider storage locations such as warehouses, distribution centers, work sites, and other storage areas. Also, consider the environment of the composite material to determine potential exposure to moisture or moist air that could cause a mold problem. Since moisture is the main component of mold growth in and around structures, the importance of moisture awareness throughout a product’s life cycle cannot be overstated. Controlling moisture levels is the most effective way to keep mold at bay. Humidity levels that may contribute to mold growth include moisture in the air (i.e. moisture) and water from sources such as leaks in the building envelope, spills, improper grading, condensation, and leaks from water supply and drainage systems. Providing architects, engineers, contractors, buyers and suppliers with information that helps them deliver optimal performance from your specific building product is a value-added service. Consider providing this information to establish or expand your position as a building materials expert and trusted supplier. Mold is a bigger problem now than ever? It’s not just the sensational news stories about “black mold” that have made mold a lively and recurring topic in the construction industry; There is more mold than ever. The tighter construction envelopes and construction materials we use ensure that mold problems will persist. Not that the amount of moisture in buildings has shifted to new levels, we still use products that are naturally damp, like concrete and drywall clay. Instead, we produce tighter construction envelopes and use larger amounts of mold-friendly (ie, cellulose-rich) materials. Neither tight building envelopes nor cellulose-rich building materials will disappear. Instead, they appear to be moving positively towards increasing energy efficiency and producing sustainable and innovative use of resources. While mold is ubiquitous in our environment, mold in building materials can be prevented by understanding environmental conditions, monitoring humidity, and addressing humidity levels. Building product manufacturers can help inform and educate suppliers, buyers, and end users to keep materials from mold throughout the lifecycle of products. A building product that performs the way it should be a surefire way to keep buyers happy and identify your products time and time again.