The charred remnants of the Omniglass fiberglass facility were heavily caked with ice but still had smoldering hot spots Tuesday afternoon, the Winnipeg Sun reported.
The fire was reported in the unoccupied building just after midnight Monday, company founder and owner Laurie Davies told the Winnipeg Free Press. He said damage was estimated at $15 million and the plant was insured.
He said he was determined to get the company running again and his 65 employees back to work.
In the early hours of fighting the blaze, eight firefighters narrowly escaped major injury when a large explosion all but collapsed one building, said Bill Clark, Winnipeg Fire Paramedic Service assistant chief of operations. Four firemen received minor injuries.
Officials said it was too early to speculate on a cause of the fire.
Omniglass has been making fiberglass window and door frames since 1983.