Facilities still contain built-in materials that were exposed to rain and snow during the construction or renovation process, leading to the presence of mould. A seminar at PM Expo last fall touched upon many other causes of mould growth and its close association to failures of the building envelope.
Some buildings can only afford reactive approaches to this fungus. The speakers, Jill Grant, director of practice leadership at Pinchin, and Jaime Hass, service line leader at Pinchin, stressed the importance of preventative maintenance, documenting water damage and how to best communicate with building occupants.
To reduce mould, it’s key to control any one of the three factors that help it grow: a food source, moisture and time. Selecting non-susceptible materials like wood and paper should be a careful process. This could mean choosing fiberglass-faced drywall over faced drywall or cement board over green board.
Mould can grow on vulnerable, organic materials within 12 hours of getting wet. All standards cite a 24- to 48-hour window to dry materials before there is a risk. Consider proactive removal of difficult-to-dry materials, such as drywall, insulation, ceiling tiles and multiple layers of finishes, and check for hidden and absorbed moisture in unexpected areas like under carpet tiles, raised flooring in IT areas and places not subjected to regular housekeeping.
“If you don’t dry materials in that window, you have to presume mould is present, unless you can thoroughly and intrusively investigate and confirm it is not,” said Grant.
Consider proactive removal of ceiling tiles, insulation and multiple layers of finishes. A flooding event may require special attention as unsanitary water could be chemically treated or laced with human pathogens. To avoid ongoing odour issues in a building, maintenance staff should avoid drying materials impacted by unsanitary water. Disinfection of structural areas will need to be followed by testing for sewage-indicator bacteria to verify cleanliness.
Professionals called in to assess water damage should follow industry accepted standards like that published by the Institute of Inspection Cleaning and Restoration Certification (IICRC). ANSI/IICRC S520 Mold Remediation is widely used across North America and is currently under revision. The standard stresses hiring certified contractors with the right experience, training and insurance for water restoration, and focuses on properly documenting the drying process for insurance and tax purposes and to avoid future repercussions.
“In the event you have another water loss, you won’t really have the back-up to show any mould growth that may have resulted was not a pre-existing condition,” said Grant.
Five causes of mould growth
Consider the building envelope
Wall assemblies can harbour excess moisture from the absorption, penetration and splashing of rain events, while ground water penetrates a building’s fabric through capillary action. Building occupant activities, from drying clothes and indoor pools to breathing, also attribute to excess moisture in the form of water vapour. Mould also results from condensation that might not be detected until other evidence shows up, such as black material at the base of a wall.
Many materials used today are “prepared to handle interior moisture,” but window and curtain wall systems have to be able to dry or move moisture out, so surface evaporation is key, noted Hass.
For evaporation and diffusion, use vapour permeable weather proof barriers in the correct location to promote outward drying. Another problem is condensation and subsequent mould occurring on the ceiling of a top floor unit, often caused by interior ambient conditions, including relative humidity levels of 69 per cent to 70 per cent.
Water infiltration through concrete floor slabs is another ongoing issue. Testing concrete floors through a moisture vapour emission rate test can help measure the rate at which water is transmitting through the concrete floor. This test should be conducted in both new and old buildings of all grade levels before installing a new floor or coating such as epoxy. Basic details such as various roof drip edge designs are “sometimes overlooked, but make all the difference,” said Hass. They help direct water from the roof edge to the gutter, without damaging other building components
Communicating with occupants and workers during remediation
Relocation during remediation is usually warranted for infants, the elderly, those with weak immune systems and strong allergies, and residents in healthcare facilities who are all considered susceptible occupants. However, anyone who is sensitive or reacting to mould growth should be evacuated.
While there isn’t a regulation for mould growth like there is for asbestos, public health and regulatory bodies will expect the best industry standard to be followed, noted Grant.
In Ontario, the key standard of care, developed by the Environmental Abatement Council of Ontario, shows how to protect workers and occupants during remediation. The Canadian Construction Association has a broader guideline during the design and construction process, encompassing assessment, health concerns and hazard communication.
All species of mould growth require special attention. In workplaces, the joint health and safety committee should be invited to view the testing and receive any resulting reports.
Both standards give detailed remediation procedures for multiple levels of work and highlight isolation of the work area, protection of workers with personal protective equipment, good hygiene practices, packaging and removal of waste, and cleaning up the work area.