The Ontario Building Code | Firewalls in Detached Garages
(1) Where a garage is detached from the dwelling unit but attached to another garage on the adjacent property, the party wall so formed shall be constructed as a fire separation having a fire-resistance ratingof not less than 45 min.
Note: On July 1, 2017, Sentence 18.104.22.168.(1) of Division B of the Regulation is amended by striking out "Where a garage is detached from the dwelling unit" at the beginning and substituting "Where a garage is detached from thehouse or the individual dwelling unit it serves". (See: O. Reg. 139/17, s. 107)