A five-alarm fire at Guelph’s recycling facility kept firefighters busy for several hours Tuesday.

Fire crews encountered heavy smoke when they arrived at the building on Dunlop Drive shortly after 10 a.m.

According to deputy fire chief John Osborne, the fire started on a conveyor belt and spread to the roof area later in the morning.

Due to the hot temperatures heightening the risk of heat exhaustion, additional firefighters were called in.

“We are having to monitor crews for heat exhaustion, we are cycling them out fairly regularly,” Osborne said.

Fire crews focused on battling the fire from inside the facility, separately attacking the fire on the roof, and stopping sparks from landing in the piles of recyclable material kept inside the building.

 “There is quite a significant pile of recyclables that are combustible and crews were very concerned about that,” Osborne said.

Forty people were able to get out of the building safely, and no firefighters were injured while fighting the blaze.

The facility is set to reopen to the public on Wednesday. City officials say there won’t be any impact on curbside collection.

The cause of the fire remains under investigation.

With reporting by Christina Marshall and Max Wark