With the prospect of legalized cannabis looming in Ontario, condominium boards throughout the GTA are rushing to figure out how to respond to a law that will permit residents to grow up to four plants inside their homes.

"We don't want to set up a system where anyone can just grow four plants and then it becomes a problem of overpopulation across units," said Tim Gordanier, a condo board president.

There's about 240 units inside Gordanier's Corktown building. Like many homeowners in the city who share walls and common areas, Gordanier is concerned about how indoor cultivation could affect a building's structure and value.

"There's the smell going into the hallway or another unit. There's also mold. I'm also concerned with people dealing [cannabis] out of their homes, which is going to affect every body."

Gordanier's says another challenge will be ensuring that residents only grow up to four plants. His board hasn't drafted a policy on home cannabis gardens, but hundreds of other boards in the province have.

Tim Gordanier is the president of a condo board with about 240 units. He says the board is discussing its options, but hopes the province will step in with better guidelines. (Sue Goodspeed/CBC News)

Lawyer estimates 400 boards have bans in place

Fine & Deo, a law firm that represents condominium corporations across Ontario, estimates that it's helped more than 400 boards implement rules.

Boards essentially govern a community, says Fine & Deo senior partner Mario Deo, adding that 80 to 90 per cent of his clients want to ban the growing and smoking of cannabis inside units.

In Ottawa and even here in Toronto, some boards have already banned residents from smoking pot inside their own homes, but Deo says exceptions have been made for those with a medical prescription.

Condo boards across the country have banned the smoking of cannabis inside units or in common areas, though there are exceptions for residents with a medical prescription to do so. (Sean Gallup/Getty Images)

When it comes to cultivation, large-scale operations with dozens of plants can damage a home's structure, says Sal Folino, home inspection manager for Carson Dunlop.

Cannabis requires warm conditions and that could lead to mold and moisture damage on floorboards or walls, Folino says. The lighting systems can increase hydro usage, he adds, and if utilities are included in a building's maintenance fees costs could go up for everyone.

Risks can be eliminated, expert says

But there are ways to minimize, even possibly eliminate, the impact pot plants have on others, says Ashley Athill, founder of Sensii, an educational organization that focuses on cannabis cultivation.

Purchasing a specialized tent to house plants "keeps the moisture inside … and ensures that someone's building or unit doesn't get affected by mold or pests," said Athill.

Ashley Athill says the condo factory tent (pictured here) can prevent mold and pests inside homes while stopping odours from seeping into other units. (Natalie Nanowski/CBC News)

Hotbox Homegrown Hydroponics in Kensington Market sells a home growing kit called a 'condo factory.' It's three feet by five feet and can house four small plants or two larger ones. It retails with an energy efficient light, which Athill estimates adds about $25 to monthly hydro costs.

As for the smell, Athill says there are odour eating gels but the best bet is to install air scrubbers inside the enclosure and run an exhaust tube out a window.

"When you excrete the air outside that air will be clean, it won't even smell," said Athill.

Even if board says yes, landlords can say no

Not everyone is convinced that odours won't be an issue for some residents, especially in buildings with relatively small units.

The Ontario Landlord Association says it's also looking into the topic. As it stands now, the law allows landlords to ban plant cultivation in their rented units even if a condo board has allowed it.

The Ontario Real Estate Association says blanket regulations don't work and wants the province to step in and create specific guidelines. In particular, OREA wants Ontario to restrict growth from four plants to one in units that are 1,000 square feet or less.

Gordanier says his board is waiting to see if the province chooses to create more regulations. Other provinces, like Quebec and Manitoba, have moved to ban home gardens entirely.