Officials have determined the Friday rooftop fire at Lakeridge Health Port Perry hospital was construction-related.
In a press release from the Town of Scugog, Fire Chief Mark Berney said "The Origin and cause was determined to be a hot tar roofing application process that ignited nearby insulation."
The estimated cost of damage from fire, smoke and water is approximately $10 million.
The fire was completely out by 8:45 p.m. Friday. The hospital remains closed to the public.
The release says "Due to the nature of the incident, external government agencies were also notified including the Ministry of Labour, Ministry of the Environment and Climate Change and the Technical Standards and Safety Authority (TSSA). All of which will conduct their own review of the incident."