The Ontario Building Code | Configuration
(1) In buildings constructed in conformance with Articles 18.104.22.168. to 22.214.171.124., the unprotected openings through floor assemblies in an interconnected floor space shall be of sufficient size and shall be positioned relative to each other so as to be capable of containing, within the full height of the interconnected floor space, a cylinder conforming to Sentence (2).
(2) The cylinder referred to in Sentence (1) shall have a cross-section that, where taken at a right angle to the longitudinal axis of such cylinder, is,
(a) a circle at least 9 m in diameter, or
(b) an ellipse at least 7 m wide along the minor axis and at least 65 m2 in area.