The massive fire at a recycling warehouse that sent dark plumes of smoke over Brisbane’s rush-hour traffic yesterday is expected to keep burning for days.

More than 20,000 cubic metres of compressed cardboard was burned and the building’s roof collapsed.

Queensland Fire and Emergency Services (QFES) Acting Superintendent Tim Clark said crews had fought the fire at Hemmant in Brisbane’s east for about four hours but had been unable to access parts of the collapsed building.

“We are doing our best to extinguish it as quickly as possible but it’s really hard to determine what the timeframe will be,” he said.

Brendan Neinert from the business next door, Thermofreeze, was not expecting to get much sleep overnight, knowing the fire was still burning.

Brendan Neinert says there are fires in the area every year. Photo: ABC News/Jemima Burt

He said he had not been concerned when he first heard about the blaze from his wife, because fire was a regular occurrence in the area.

“Generally, one of these buildings around here is on fire every year, so we don’t think too much of it,” he said.

But this fire was out of the ordinary.

Four people escaped unharmed from the building in Gosport Street when the fire broke out at 2:30pm yesterday and nearby businesses were evacuated.

“It went from a single pallet fire to a full building,” Mr Neinert said.

He said they had not noticed any fire damage to their building, but would wait for a formal assessment.

“Luckily, we’re a cold storage facility, so I think that’s aided us a little bit.”

The blaze started in piles of compacted paper, cardboard and plastic outside the warehouse before spreading to other parts of the building.

Sixteen fire units were able to protect other commercial properties in the area.

Firefighters used cranes to get closer to the flames. Photo: ABC News

Acting Superintendent Clark said it could have been a lot worse.

“It had a massive potential to extend into neighbouring properties … I’ve got to really commend the crew,” he said.

“They’ve been working under extreme conditions to protect those unaffected buildings.

“So far they’ve done a fantastic job and I’m sure that will continue.”

The cause of the fire remains unknown.

Initial investigations are expected to begin tomorrow.

-ABC