Getting a hold on mold in construction
Mold lives everywhere in air, in water, on land, in soil, and on or in plants and animals. All it needs to grow is the right temperature, moisture, and a nutrient source. Despite many harmless and beneficial molds, some molds can be toxic and pose very serious health threats to humans. That is why few want mold growing where they live or work. That’s why contractors, being the first gatekeeper in preventing a moisture intrusion, need to take appropriate precautions to prevent mold from getting a hold during construction.
Because mold “eats” or digests what it is growing on, it will gradually damage whatever it grows on. And that can be a problem for contractors. Much of the construction material used to build residences and commercial buildings in the US is composed of organic materials including particleboard, wood studs, wallboard and ceiling tiles. Under proper conditions, these materials are readily available food sources for mold, which may start to grow in a little as 24 to 48 hours. And once mold growth is established on such materials, it is often difficult to eliminate. Mold can even grow on the dust and dirt present on inorganic construction materials such as concrete, metal, and glass.
That’s not contractors’ only worry with mold. In addition to the structural damage that mold can do, indoor air quality concerns from elevated levels of mold reproductive structures (called spores) and mold metabolites (called mycotoxins) have been associated with causing a variety of adverse health effects in humans. The US Environmental Protection Agency (EPA) cautions that all molds produce allergens and irritants that can cause health problems under the right conditions. Often included in the list of toxic molds is Stachybotrys Chartarum, a greenish-black mold, which can grow on high cellulose, low nitrogen materials such as fiberboard, drywall, paper, dust and lint – in the presence of moisture. Its effects when airborne are particularly of concern for building occupants with impaired immune systems such as the very young, the elderly, and those individuals who are immune-suppressed.
If the health concerns and associated bodily injury claims aren’t motivation enough to control mold growth, construction firms should be concerned with the increase in legal actions against builders in which claimants allege faulty designs or construction defects have contributed to water intrusion and mold contamination. Jury awards have been significant in several cases. Claims activity is often driven by improper use and installation of products that trap moisture such as insulating systems, flashing and drainage systems, and wall coverings/vapor barriers.
Construction firms are wise to recognize the importance of preventing mold growth, from the start. Some proactive considerations should include:
Materials used in construction must be protected during transport, delivery and storage before shipment to the jobsite and at the jobsite during construction. Moisture can impact uninstalled porous materials such as wallboard, and other building equipment such as air handlers and ducts awaiting installation. It is important that materials are inspected when they arrive at the site to ensure they are in acceptable condition and free from water-damage and mold.
Once the building is framed out – i.e., roof, doors and windows, etc. – it is important to frequently inspect the areas that remain open to move materials into the building, as well as any incomplete building envelope areas where moisture can enter. A higher risk period of several months or longer is typically present on virtually every project prior to fully closing in the building. This is also the time when water-sensitive materials are beginning to be used in the construction processes.
It is highly recommended that construction firms develop and implement a written Water Intrusion Management Plan to control moisture sources and prevent mold growth. The plan should clearly outline responsibilities, including inspection protocols, pre-construction design and planning, construction phase controls, and emergency response. Contractors and subcontractors should be trained on plan requirements to assist with effective implementation. For more information, download AXA XL’s Water Intrusion Management Plan for Construction Firms, which provides a basic template for starting a plan.
Construction management should also periodically monitor the project site, like during routine inspection walkthroughs, to ensure the provisions of the water intrusion management plan are enforced. This is considered an essential best management practice for identifying plumbing leaks and building envelope problems before they become catastrophic.