Movement joint
Movement joint covers control, expansion, articulation joints absorbing thermal, moisture, or structural movement. AS 3958 mandates them in tile fields.
Ask Chalkline about this →A movement joint is the umbrella term for any deliberate joint in a continuous tiled floor, render face, masonry wall, or other rigid surface that lets the surface absorb thermal expansion, moisture-driven movement, structural settlement, or differential foundation movement without cracking. Movement joints subdivide into three more-specific types:
| Type | Movement absorbed | Typical detail |
|---|---|---|
| Control joint | Drying shrinkage in concrete or render | Sawn or formed shallow break to localise the crack |
| Expansion joint | Thermal expansion | Backer rod + sealant in a full-depth gap |
| Articulation joint | Differential foundation movement in masonry walls | Full-height vertical break, both leaves on cavity masonry |
The term “movement joint” appears in AS 3958.1 (tile installation), AS 3700 (masonry structures), and AS 2870 (residential slabs) without strictly distinguishing between expansion and control mechanisms; in residential practice the same physical joint often does both jobs.
Where movement joints are required (AS 3958.1 for tiled floors):
| Location | Maximum spacing |
|---|---|
| Perimeter of every tiled floor (against walls, columns, kitchen joinery) | Always required, 6 to 10 mm wide |
| Intermediate joints in tiled floors | 4.5 m maximum on internal floors, smaller in external |
| At every structural movement joint in the substrate | Mirror the underlying joint |
| Around any rigid penetration (drain, pipe, column) | Maintained around the obstruction |
Failure to provide the perimeter joint or to space intermediate joints correctly is the most common cause of tile cracking in residential at 6 to 18 months of age. The tile field absorbs the substrate’s thermal cycling and cracks where no joint relieves the stress.
Movement joint construction (typical residential tile install):
- Joint gap formed at the substrate before tiling (8-10 mm).
- Tile laid up to the joint with no tile bridging the gap.
- Backer rod (closed-cell foam) inserted into the joint to set the sealant depth.
- Flexible sealant (silicone or polyurethane) applied over the backer rod, tooled flush or slightly recessed.
The grout substitution defect. A common builder shortcut is filling the movement joint with grout (the same grey or coloured grout used between tiles). Grout is rigid; it doesn’t accommodate movement; the joint cracks at the first temperature swing. Always use flexible sealant (silicone or polyurethane), never grout.
Distinguishing the three subtypes (when does it matter):
- The certifier and the contract spec will sometimes call out a specific type (e.g. “articulation joints at 7.5 m centres on the masonry wall”).
- For everyday residential, “movement joint” covers the design intent and the installer reads the spec.
Also known as: flexible joint; sealant joint (sometimes); building movement joint.
Category: Structure.
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Last updated: 2026-05-16. Verified: 2026-05-16. Quarterly review for currency.