(1)
Concealed spaces in interior wall, ceiling and crawl spaces shall be separated from concealed spaces in exterior walls and attic or roof spaces by fire blocks. (See Note A-2.2.1.8.(1))
(2)
Concealed spaces in walls and partitions shall be separated by fire blocks into compartments not more than 3 m in height and 20 m in length.
(3)
Horizontal concealed spaces within a floor assembly or roof assembly of combustible construction, in which sprinklers are not installed, shall be separated by fire blocks into compartments not more than 900 m
(4)
Except as permitted by Sentence (5), fire blocks shall be constructed of materials that will remain in place and prevent the passage of flames for not less than 15 min when subjected to the standard fire exposure in CAN/ULC-S101, “Standard Method of Fire Endurance Tests of Building Construction and Materials.”
(5)
Fire blocks need not be tested in conformance with Sentence (4) if they are constructed of not less than
(a)
0.38 mm sheet steel,
(b)
12.7 mm gypsum board,
(c)
12.5 mm plywood, OSB or waferboard, with joints backed with similar material,
(d)
two layers of lumber, each not less than 19 mm thick, with joints staggered, or
(e)
38 mm lumber.