The Ontario Building Code | Continuity of Firewalls
188.8.131.52. Continuity of Firewalls
(1) A firewall shall extend from the ground continuously through, or adjacent to, all storeysof a building or buildingsso separated, except that a firewall located above a basement storage garageconforming to Article 184.108.40.206. is permitted to commence at the floor assembly immediately above the storage garage.
(2) A firewall is permitted to terminate on the underside of a reinforced concrete roof slab provided,
(a) the roof slab on both sides of thefirewall has a fire-resistance rating not less than,
(i) 1 h if the firewall is required to have a fire-resistance rating not less than 2 h, or
(ii) 2 h if the firewall is required to have a fire-resistance rating not less than 4 h, and
(b) there are no concealed spaces within the roof slab in that portion immediately above the firewall.