Part 5.3 Cavity masonry
5.3.1
Application
New for 2022
5.3.2
Height of wall limitation
New for 2022
Cavity masonry walls must not be greater than 8.5 m in height when measured above the adjacent finished ground level.
5.3.3
External walls
New for 2022
- The height of the wall between lateral supports (floor or ceiling or roof diaphragm) must be not more than 3 m.
- Cavity masonry walls subject to wind loads must be supported by masonry cross walls or by steel mullions complying with (3).
- Masonry cross walls must be—
- not less than 2 m in length; and
- at not more than 5.1 m centres where the length of the cavity wall being supported does not contain any opening or control joint; and
- not more than 2.5 m from the edge of a control joint in the length of the cavity wall being supported; and
- not more than a distance from the edge of an opening in the length of the cavity wall being supported as stated in Table 5.3.3; and
- located at both edges of openings of width greater than 2.7 m; and
- directly connected to the internal leaf of the cavity wall being supported using—
- properly bonded units with at least 90 mm engagement on each side of the interface with the selected bond pattern but not less than every fourth course of masonry; or
- medium duty Type A cavity wall ties in aligning mortar bed joints at a vertical spacing of not more than 300 mm; and
- connected by a floor or ceiling diaphragm to the wall being supported where floor or ceiling connections are designed in accordance with AS/NZS 4600, AS 1720.1 or AS 3600, as appropriate.
- The cavity must be not less than 35 mm and not more than 75 mm in width, in accordance with 5.7.2.
- Except for steel mullions, the minimum cavity width specified in (a) is to be maintained between the outer masonry leaf and any insulation or services located in the cavity.
- Where steel mullions are located in a cavity as permitted by (b), a vertical damp-proof course must be placed between the outer masonry leaf and the mullion to prevent moisture penetration.
Wind class | Opening width (mm) | |||
---|---|---|---|---|
900 | 1500 | 2100 | 2700 | |
N3 | 2100 | 1800 | 800 | 400 |
N2 | 3200 | 2900 | 2600 | 2300 |
N1 | 2500(Note) | 2200(Note) | 1900(Note) | 800(Note) |
Explanatory information
Steel mullions complying with AS 4773.1 and 4773.2 used to support wind loads may be placed within a cavity. Flat ceiling capable of performing diaphragm action may act as lateral support to walls provided the structure has been specifically designed.
5.3.4
Internal walls
New for 2022
- not less than 75 mm thick; and
- either—
- bonded at the junctions of the intersecting walls; or
- provided with an articulation joint in accordance with 5.6.8.
5.3.5
Openings in cavity masonry
New for 2022
Explanatory information
An opening of not more than 500 mm is considered to be adequately supported if the masonry bears directly on a timber window head or steel frame.
5.3.6
Damp-proof courses and flashing materials
New for 2022
Damp-proof courses and flashing must be provided in accordance with 5.7.3 and 5.7.4.
5.3.7
Vertical articulation joints
New for 2022
Vertical articulation joints are to be installed in accordance with 5.6.8.