The Ontario Building Code | General
11.4.3.1. General
(1) Where the performance level of an existing buildingis reduced under Subsection 11.4.2., compensating constructionshall be carried out in accordance with this Subsection.
(2) Except as provided in Sentence (3), compensating constructionrequired under this Subsection applies to the part of the buildingbeing altered and shall include,
(a) fire separations, with the required fire-resistance ratings, separating the part being altered from the floor areas immediately above and below and from the immediate adjacent areas, and
(b) access to exits and exits from the building, where the alteration adversely affects the exit system of the building.
(3) Compensating construction required under this Subsection applies to the existing building systems that are adversely affected by the proposed construction.