The Office of the Ontario Fire Marshall hasn't yet completed their investigation, but say the fire at the Agincourt Rec Centre is accidental.
They are focusing their attention on an electrical fixture and wiring on the north wall, contained in the cedar cladding on the outside wall of the pool.
Chris Ter Stege from the OFM says the fire and super-heated air quickly moved up into the ventilation of the building, making it very stubborn for crews to get under control.
Once it was out, the investigators located the likely ignition source in the outside cedar siding, above the brick and windows.
"On that cedar cladding, we only had one potential ignition source, and it was electrically ‘generized’." says Ter Stege.
He says they are now examining some circuits, as well as a lighting fixture on the outside of the building. Some of the wiring for the emergency lighting has also been sent for examination.
He says there doesn't appear to be anything suspicious or any deficiencies with the maintenance of the building.
"It appears to be over time, just a failure. There's no issues with maintenance, or anything that's wrong with the construction of the building itself."
There were no injuries during the nearly 40 hours of fighting the fire and the building was not a complete loss.
Fire crews managed to keep the fire and smoke away from the arena portion of the building.