The Ontario Building Code | Fire Blocks between Vertical and Horizontal Spaces

3.1.11.4. Fire Blocks between Vertical and Horizontal Spaces

(1) Fire blocksconforming to Article 3.1.11.7. shall be provided,

(a) at all interconnections between concealed vertical and horizontal spaces in interior coved ceilings, drop ceilings and soffits in which the exposed construction materials within the space have a flame‑spread rating more than 25, and

(b) at the end of each run and at each floor level in concealed spaces between stair stringers in which the exposed construction materials within the space have a flame‑spread rating more than 25.