Here on the wet West Coast, mould is a topic of concern for many prospective homebuyers.
Few want to invest in such a significant purchase only to find an infestation of mould that requires significant – and potentially costly – remediation.
For those shopping for one of Oak Bay’s older homes, the good news is that the materials and building techniques used in many of these homes actually make mould control fairly simple, says Ryan Ractliffe, environmental scientist and owner of Axiom Mould Experts.
Before drywall was the go-to choice for wall covering, lathe and plaster was less permeable and without drywall’s paper backing, and thus less hospitable to mould spores, explains Ractliffe, who has spent a decade in the industry. Traditional methods to tackle mould, such as washing with hydrogen peroxide at three per cent, were also more effective.
Fast-forward to the 1970s and ‘80s and the push to make homes airtight, and the resulting moisture found a happy home with new materials such as pine and porous drywall, “much more susceptible to mould growth,” Ractliffe says.
“Drywall is a porous medium and the paper on each side of the drywall is food for the mould.”
Here in Oak Bay, typical problem areas can be renovated basements and bathrooms, where these newer materials and techniques have been used during upgrades.
When moisture and mould settle into these materials, they’re able to reach into areas out of sight, such as behind baseboards and inside walls; once that’s happens, remediation is often required and because of potential toxicity, proper evaluation and safety measures are essential.
Drywall that pre-dates about 1990, for example, must be checked for asbestos before being cut or removed, Ractliffe notes.
Because moulds also differ greatly – and can’t be accurately identified by the naked eye – samples must also be analyzed so you know what you’re dealing with. “Not all moulds are created equally,” he says.
Mould in attics can be different than that found in the rest of the home. In the attic, where mould often arises due to trapped humidity and poor ventilation, because air moves upward, it doesn’t necessarily mean there’s mould elsewhere in the home.
“Just because there’s mould in the attic doesn’t mean there’s poor air quality in the home,” Ractliffe says.
Not so with the basements and crawl spaces, however, where the air can move the microbial volatile organic compounds into the living space.
Mould that isn’t visible – behind walls or in the crawlspace, for example – can still cause problems.
“It’s the off-gassing of mould and the accumulation of fungal spores,” Ractliffe says.
Both can cause headaches, respiratory problems and allergic reactions. Additional symptoms to watch for include general fatigue, colds and flus that stick around longer than normal and a scratchy, sore throat.
In particular, Ractliffe advises people to pay attention if such symptoms seem to improve when they’re out of the house.
“If they’re away from the house for any extended time and they’re noticing changes in their symptoms, that’s a big red flag that they need to address the indoor air quality in their home,” he says, recommending homeowners invest in an air purifier with hepa/carbon filter.
Not everyone is as sensitive to the spores and off-gassing, he notes, adding some individuals, including those with compromised immune symptoms, can be “the proverbial canary in the coal mine for the home.”
Chief among prevention measures are controlling humidity in the home and preventing moisture intrusion.
Humidity should ideally be kept at around 50 per cent; once it’s at 70 per cent or so, homeowners will start to see moisture on colder surfaces. Typically this happens in fall when homes are closed up for winter.
“Just control the relative humidity within the home, keeping it as close to 50 per cent as possible, and ventilate when the weather is good,” Ractliffe suggests.
Moisture intrusion typically happens from an internal or external flooding problem, or a foundation leak.
In that case, the best practice is to remove affected drywall rather than simply drying it out as mould can begin growing quickly.