Windsor fire officials say the fire at former Pour House bar was intentionally set and caused $75,000 in damage.
The fire started at the rear of the building exterior on Chatham Street Sunday afternoon.
Heavy, black smoke filled parts of the downtown core around 2:30 p.m. Thick smoke could be seen coming from the first and second floors of the former Pour House Pub on Chatham Street. More than three dozen firefighters and nine trucks were on the scene to tackle the blaze.
Officials say they had a difficult time controlling the fire because the three-storey building was under construction, with no separation between the floors. High winds also hampered efforts to douse the flames.
The investigation into the blaze is now complete.