My Library

Table 28 Minimum thickness of wall sheathing Minimum Thickness, mm (in.) Type of Sheathing
With Supports 400 (16) o.c.
With Supports 500 (20) o.c.
With Supports 600 (24) o.c.
Material Standards
Structural Fibreboard (insulating)
9.5 (3⁄8)
-
11.1 (7⁄16)
CAN/CSA-A247
Gypsum sheathing
9.5 (3⁄8)
-
12.7 (1⁄2)
CAN/CSA-A82.27-M
Plywood (exterior type)
6.0 (1⁄4)
-
7.5 (5⁄16)
CSA O121-M CSA O151-M CSA O153-M
OSB, O-1 grade, and waferboard, R-1 grade
6.35 (1⁄4)
-
7.9 (5⁄16)
CSA O437.0
Panel mark (performance-rated panels)
W16
W20
W24
CSA O325.0
Lumber
17.0 (11⁄16)
-
17.0 (11⁄16)
See Table 7
Mineral fibre, rigid board, type 2
25 (1)
-
25 (1)
CSA A101-M
OSB, O-2 grade
6.0 (1⁄4)
-
7.5 (5⁄16)
CSA O437.0
Phenolic, faced
25 (1)
-
25 (1)
CAN/CGSB-51.25-M
Non-Structural Expanded polystyrene (Types 1 and 2)
38 (11⁄2)
38 (11⁄2)
CAN/CGSB-51.20-M
Expanded polystyrene (Types 3 and 4)
25 (1)
25 (1)
CAN/CGSB-51.20-M
Urethane and isocyanurate (Types 1, 2 and 4)
38 (11⁄2)
38 (11⁄2)
CGSB 51-GP-21M
Urethane and isocyanurate (Type 3)
25 (1)
25 (1)
CGSB 51-GP-21M
Urethane and isocyanurate (Types 1 and 2), faced
25 (1)
25 (1)
CAN/CGSB-51.26-M