ABCB Housing Provisions
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5.4

Part 5.4 Unreinforced single leaf masonry

Part 5.4 Unreinforced single leaf masonry

(1) Part 5.4 applies subject to the limitations set out in H1D5(3)(c).

(2) Part 5.4 need not be complied with if H1D5(3)(a) or (b) are complied with.

(1) Single leaf unreinforced masonry walls with engaged piers and return walls must comply with the relevant provisions of this Part and be constructed in accordance with the following:

  1. The roof frame must be connected continuously to the top of the wall (see Figure 5.4.2a).
  2. Stack bonded piers must have wall ties at every fourth course.
  3. Pier and return supports size limitations for—
    1. single leaf unreinforced masonry walls with engaged piers, must comply with Table 5.4.2a and Figure 5.4.2b; and
    2. single leaf unreinforced masonry walls with return supports, must comply with Table 5.4.2b and Figure 5.4.2c.
  4. An engaged pier or return wall must be provided at both sides of an opening.
  5. The width of an opening must be not more than the spacing between the engaged piers unless the engaged piers either side of the opening are designed in accordance with AS 3700.
  6. Articulation joints must be located within 300 mm of vertical supports in accordance with 5.6.8.

(2) A Class 10a building containing not more than 1 storey may be enclosed with single leaf masonry external walls not less than 90 mm in thickness, provided that—

  1. the building measured in the direction of the span of the roof is not more than 9 m and the height is not more than 2.7m; and
  2. engaged piers are provided that are in accordance with Tables 5.4.2c and 5.4.2d; and
  3. the roof does not place any spreading thrust onto the external walls; and
  4. the Class 10a building is located in an area with a wind class of not more than N2.
Table 5.4.2a Engaged piers in external single leaf masonry walls to AS 3700
Element Symbol used in Figure 5.4.2b Thickness of wall (T)
90 110
Pier size (minimum) (not more than N2) A x B 290 x 190 (800 spacing) 350 x 230 (1150 spacing)
Pier size (minimum) (not more than N3) A x B 290 x 290 (700 spacing) 350 x 350 (1050 spacing)
Spacing of returns (maximum) S 700 1050
Height (maximum) H 2400 2700
Table Notes
  1. Dimensions are in mm.
  2. Return supports are not required for 140 mm and 190 mm thick walls.
Table 5.4.2b Return support limitations for external single leaf masonry walls to AS 3700
Element Symbol used in Figure 5.4.2c Thickness of wall (T)
90 110 140 190
Return length (minimum) R 450 450 – –
Spacing of returns (maximum) (N2) S 1050 1300 – –
Spacing of returns (maximum) (N3) S 600 750 – –
Height (maximum) H 2400 2400 1700 (N2) 2300 (N2)
Table Notes
  1. Dimensions are in mm.
  2. Return supports are not required for 140 mm and 190 mm thick walls.
Table 5.4.2c Engaged piers in external walls of Class 10a buildings — wall height: 2.4 m
Wall thickness (mm) Pier thickness (mm) Pier width (mm) Spacing (mm) for wind class
N1 N2
90 190 290 1000 600
90 290 190 1700 1200
90 290 290 2600 1800
110 230 230 1320 840
110 230 350 2040 1320
110 350 230 3240 2160
110 350 350 4920 3360
Table 5.4.2d Engaged piers in external walls of Class 10a building — wall height: 2.7 m
Wall thickness (mm) Pier thickness (mm) Pier width (mm) Spacing (mm) for wind class
N1 N2
90 190 290 700 500
90 290 190 1300 900
90 290 290 2000 1400
110 230 230 960 600
110 230 350 1440 960
110 350 230 2520 1680
110 350 350 3840 2520
Figure 5.4.2a Top lateral restraint detail for unreinforced single leaf masonry walls
image-5-4-2a-top-lateral-restraint-detail-for-unreinforced-single-leaf-masonry-walls.svg
Figure Notes

Tie down of wall must comply with 5.6.6.

Figure 5.4.2b Engaged piers in external single leaf masonry walls to AS 3700
image-5-4-2b-piers-in-external-single-leaf-masonry-walls-to-AS-3700.svg
Figure 5.4.2c Return support limitations for external single leaf masonry walls to AS 3700
image-5-4-2c-return-support-limitations-for-external-single-leaf-masonry-walls-to-AS-3700.svg

Internal masonry walls must be engaged with other walls, must comply with the relevant provisions of this Part and must be—

  1. not less than 75 mm thick; and
  2. supported by either—
    1. the ceiling structure in accordance with Figure 5.4.3a; or
    2. return walls in accordance with Figure 5.4.3b.
Figure 5.4.3a Support for internal walls—supported by ceiling structure
image-5-4-3a-support-for-internal-walls-supported-by-ceiling-structure.svg
Figure Notes
  1. Timber joist must be fixed to top plate in accordance with H1D6(4).
  2. Fixing of top plate to masonry wall must be in accordance with 5.6.6.
Figure 5.4.3b Support for internal walls—supported by return walls
image-5-4-3b-support-for-internal-walls-supported-by-return-walls.svg
Figure Notes
  1. An opening of not more than 600 mm x 900 mm is allowed to internal walls without additional support.
  2. Openings larger than as described in Note 1 and door openings must be supported.
  3. The maximum allowable height for the wall is described in Figure 5.4.3a.
  4. Articulation joints must be in accordance with 5.6.8.

Explanatory information

A full height door frame or stud fastened at the roof framing and tied to the wall at 300 mm centres can be considered equivalent to a return wall.

Vertical articulation joints must be provided in accordance with 5.6.8.

Where required, damp-proof courses and flashing must be provided in accordance with 5.7.3 and 5.7.4.