#Using Tide to kill roof moss is a bad idea. Some B.C. condo owners learned that the hard way.

Just after lunch on a Saturday in May, about 30 employees of Belfor Property Restoration, wearing hard hats and orange safety vests, headed to the rooftops of Sage at Auguston, a large townhouse complex in Abbotsford, B.C.

Three women watched from adjacent balconies as five boom lifts lined up along a lane hoisted some of the workers to the pitched, two-storey roofs; other crew members walked through the picket-fenced yards of the complex, which is tucked into the verdant side of Sumas Mountain. From there, they climbed ladders and gently hosed down the rooftops with water. A vacuum truck intercepted the resulting runoff before it drained into a nearby forest.

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The onlooking residents were in no mood to chat, though one volunteered a crisp response when asked how she was feeling about the cleanup: “S–tty.”

The mop-up, and the raw feelings, stemmed from a maintenance mistake that had recently landed the community in the news. During the last week of April, a one-man contracting service had used Tide detergent powder as a DIY herbicide, sprinkling an estimated 100 kilograms over some 120 rooftops in the complex in an effort to kill the moss that can build up on shingles in B.C.’s coastal climate.

Then, as it does about 174 days a year in Abbotsford, it rained, washing the detergent off the roofs, sluicing it down lanes and through three culverts that slope toward the forest and feed into nearby Clayburn Creek.

Thus began what might be described as a suds-flood. On three occasions over the ensuing week, foam bubbled as high as 2.5 metres from the creek bed. On April 30, witnesses said, it flowed as far as four kilometres. “I thought it was a terrible teenage prank,” says one woman who often walks a popular pathway along the banks of the creek (she asked that her name not be used). Other hikers and residents reported the foam mountains to the strata council, the city of Abbotsford, the province, the federal government and the media. One was Tom Ulanowski. He’s lived at Sage at Auguston for five years and saw the foam when he and his wife took their child for a hike along the creek. As the vice-president of quality and regulatory affairs at a cannabis company, Ulanowski holds degrees in analytical chemistry and environmental monitoring.

“I was quite shocked and concerned,” Ulanowski told CBC. He worried some chemicals in Tide could harm aquatic life in Clayburn. The creek is a spawning area for coho salmon, cutthroat trout and several other fish species. There were reports of a video showing fish swimming through foam.

According to a 2010 sensitive ecosystems study by the city of Abbotsford, Sumas Mountain is a 6,600-hectare “biological hot spot” inhabited by at least 40 species at risk, including the Pacific giant salamander and the coastal tailed frog.

But take a quick look around the internet and you’ll find people living in coastal areas like Oregon and other parts of B.C. pushing the notion that Tide is a cheap, effective way to deal with rooftop moss. It does kill moss. But many professional roofers advise against the practice, warning not only of the environmental hazard but also that it’s bad for roofing materials.

In B.C., “the home of moss,” says roofer Murray Tysowski, any contractor endorsing the use of detergent is “looking for trouble.” Tysowski, who owns Aurora Roofing in mossy Coombs, on Vancouver Island, speaks with some authority: he is president of the Roofing Contractors Association of B.C. and a vice-president of the Canadian Roofing Contractors Association (CRCA).

Troy Ferreira, the CRCA’s technical director, says that, while moss roots can penetrate, lift and damage wooden shakes and ordinary asphalt shingles, detergents can do worse in a shorter period of time. The surfactants in many of them—degreasers that help get the spilled mustard and oily stains out of your clothes—also attack the oils in asphalt shingles, loosening the granules in them. And if the granules come off, says Ferreira, “those shingles are going to fail prematurely.”

Tysowski has heard of individual homeowners using detergent, but never on the “unbelievable” scale seen in Abbotsford. He regards moss as mostly an aesthetic problem, adding there are environmentally safe products available to kill it, such as Scotts EcoSense Moss B Gon. In most cases, he says, gently scraping or sweeping it from between shingles is the safest remedy.

The ill feeling among residents of Sage at Auguston is understandable, given the potential cleanup costs, which may be in the hundreds of thousands of dollars. The strata corporation uses a third-party company, Campbell Strata Management Ltd., to take care of maintenance. According to information shared with strata residents, Campbell hired the contractor who applied the Tide, but it wasn’t clear whether the property manager or anyone on the strata council was aware he intended to use it. Campbell Strata did not respond to interview requests, while both the contractor and a representative of the strata council declined to comment.

But Tony Gioventu, executive director of the Condominium Home Owners Association of B.C. (CHOA), notes that, under B.C. law, the individual owners of condos, townhomes or apartments in each strata are collectively responsible—and liable—for anything the strata and its council do.

And with 32,000 such strata corporations in the province, the stakes for residents are high. Gioventu, who for nearly 20 years has written a newspaper column called “Condo Smarts” that runs weekly in the Province and Victoria’s Times Colonist, says lessons from the Abbotsford fiasco will be one of his future topics.

Across Canada, he says, “we have a lot of individuals doing maintenance work and small construction jobs for condo and strata buildings out of the back of their trucks.” Many work without proper licences and permits, he says, and that exposes unit owners to financial risk arising from mistakes or shoddy work. Already the city of Abbotsford has slapped the Sage strata and contractor with a total of $2,000 in fines for contravening sewage and waterways bylaws. More penalties from other levels of government could be coming.

Meanwhile, the moss lives on at Sage at Auguston. Gioventu figures the whole mess could have been avoided if someone—the strata council, the property management company or the contractor who sprinkled the Tide—had checked B.C.’s registry of roofing inspectors and called one to advise them on how to address the problem. “People get lured in by these quick-fix solutions,” he says. “You can almost guarantee every time that it’s too good to be true.”

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This article appears in print in the July 2021 issue of Maclean’s magazine with the headline, “Soap on a roof.” Subscribe to the monthly print magazine here.