PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code
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9.11.1.4.Adjoining Constructions (See Note A-9.11.1.4.)
(1) This Article applies where the required protection is provided in accordance with Clause 9.11.1.1.(1)(b) and
compliance is demonstrated in accordance with Clause 9.11.1.3.(2)(b).
(2) Flanking wall assemblies connected to a separating floor or ceiling assembly shall be constructed with
(a) concrete or concrete block having a mass per area greater than 200 kg/m2, or
(b) gypsum board finish that
(i) is supported on wood or steel framing, and
(ii) ends or is interrupted where it meets the structure of the separating floor or ceiling assembly.
(3) Flanking wall and ceiling assemblies connected to a separating wall assembly shall be constructed with
(a) concrete or concrete block having a mass per area greater than 300 kg/m 2, or
(b) gypsum board finish that
(i) is supported on wood or steel framing, and
(ii) ends or is interrupted where it meets the structure of the separating wall assembly or, for double-stud walls,
where it meets the space between the two lines of studs.
(4) Flanking floor assemblies connected to a separating wall assembly shall be
(a) constructed
(i) with concrete having a mass per area greater than 300 kg/m 2, or
(ii) in accordance with Section 9.16., or
(b) supported on joists or trusses that are not continuous across the junction and are covered with floor treatments in
accordance with Table 9.11.1.4. for the applicable wall construction.
Table 9.11.1.4.
Floor Treatments for Flanking Wood-Framed Floor Assemblies in Horizontally Adjoining Spaces
Forming Part of Sentence 9.11.1.4.(4)
Type of Separating Wall Assembly
with STC ≥ 50 from Minimum Requirements for Floor Treatments Applied over Subfloor of Wood-Framed
MMAH Supplementary Standard SB-3, “Fire Flanking Floor Assemblies on Both Sides of Floor/Wall Junction
and Sound Resistance Tables”
• wood strip flooring not less than 16 mm thick aligned parallel to separating wall, or
• one layer OSB or plywood not less than 15.5 mm thick plus finished flooring, or
W5, W6, W10, W12 (staggered studs)
• one additional material layer plus finished flooring having a combined mass per area
not less than 8 kg/m²(1)
• one layer of OSB or plywood not less than 12.5 mm thick plus hardwood strip flooring
not less than 19 mm thick aligned parallel to separating wall, or
W4, W11 (staggered studs)
• one additional material layer plus finished flooring having a combined mass per area
not less than 16 kg/m²(1)
• concrete or gypsum concrete topping not less than 19 mm thick bonded to the subfloor
plus finished flooring, or
W8, W9 (staggered studs)
• one additional material layer plus finished flooring having a combined mass per area
not less than 32 kg/m²(1)
Table 9.11.1.4. (Cont’d)
Floor Treatments for Flanking Wood-Framed Floor Assemblies in Horizontally Adjoining Spaces
Forming Part of Sentence 9.11.1.4.(4)
Type of Separating Wall Assembly
with STC ≥ 50 from Minimum Requirements for Floor Treatments Applied over Subfloor of Wood-Framed
MMAH Supplementary Standard SB-3, “Fire Flanking Floor Assemblies on Both Sides of Floor/Wall Junction
and Sound Resistance Tables”
• where a continuous subfloor or other rigid materials at the floor/wall junction provide
structural connection between the two rows of studs in the separating wall:
• hardwood strip flooring not less than 16 mm thick aligned parallel to separating
wall, or
• one layer OSB or plywood not less than 15.5 mm thick plus finished flooring, or
W13, W14, W15 (double stud walls)
• one additional material layer plus finished flooring having a combined mass per
area not less than 8 kg/m²(1)
• any finished flooring where the subfloor and other rigid materials are not connected at
the floor/wall junction and where there are no structural connections between the two
rows of studs in the separating wall
B1 to B10 • any finished flooring
Notes to Table 9.11.1.4.:
(1) See Note A-Table 9.11.1.4.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.