Our Adelaide brick veneer house on a reactive clay site has long unbroken walls, and the engineer flagged articulation joints. How far apart do articulation joints need to be in masonry veneer, and what sets the spacing?

The engineer is right, and the reason is the soil, not the wall. Vertical articulation joints must be provided in masonry walls except on sites classified A or S. [1] A reactive clay site is neither, so the joints are mandatory. [4]

Two questions people run together. The soil class decides whether you need joints. It does not set how far apart they go. [1] Spacing comes from the shape of the wall, set out in 5.6.8(2). [1]

Spacing and placement. Every joint must be not less than 10 mm wide. [1] Then: [1]

• Straight, continuous walls without openings, or with openings less than 900 mm x 900 mm: joints at not more than 6 m centres, and within 4.5 m of all corners but not closer than 470 mm to a corner.
• Straight, continuous walls with openings more than 900 mm x 900 mm: joints at not more than 5 m centres, positioned so none is more than 1.2 m from an opening.

Joints that are needed wherever these occur, regardless of spacing. [1]

• Where the wall height changes by more than 20%, at the position of the change.
• Where the wall changes in thickness.
• At control or construction joints in footings or slabs.
• At junctions of walls built from different masonry materials.

Where not to put them. Articulation joints must not be located adjacent to arched openings. [1]

How the joint is built. Fill it with flexible sealant, supported during installation by either a compressible foam or polystyrene filler or a purpose made backer rod. [1] Wall ties go on both sides of each joint, within 300 mm of it. [3]

The margin people miss. A wall with a window larger than 900 mm x 900 mm switches from 6 m to 5 m centres, and it also needs a joint within 1.2 m of that opening. On a long wall with a few big windows, the opening rule usually decides the layout, not the 6 m figure. Also note the 2022 wording: the 6 m rule covers openings less than 900 mm x 900 mm and the 5 m rule covers openings more than 900 mm x 900 mm, so an opening of exactly 900 mm x 900 mm falls between them. NCC 2025 closes that gap by saying "not more than". [2] Treat an exactly 900 mm opening under the tighter 5 m rule and tell the certifier you have.

Next step. Ask the engineer for the site classification and the footing and slab control joint locations, because those joints fix the position of wall joints under 5.6.8(2)(e). Then set out the remaining joints from the corner and opening rules above.

SA edition note. NCC 2022 applies to SA building work until 30 April 2027, and NCC 2025 applies from 1 May 2027. [5] The 6 m and 5 m spacings, the 10 mm minimum width and the A and S exemption are the same in NCC 2025. [2]