An expansion joint is a deliberate gap in a structure that allows for thermal expansion, contraction and settlement. Without expansion joints, cracks can appear in walls, floors and facades because materials expand when warm and contract when cold.
Where are expansion joints used?
| Location | Typical spacing | Reason |
|---|---|---|
| Brick facades | Every 6-8 metres | Thermal expansion of brickwork |
| Concrete floors | Every 4-6 metres | Shrinkage during curing, temperature |
| Tiled floors | Every 5-6 metres + at transitions | Expansion of tiles and screed |
| Tiled walls | At corners and junctions | Movement between wall and floor |
| Paving | Every 6-10 metres | Thermal expansion |
How is an expansion joint made?
In masonry
- A continuous vertical joint through the wall, filled with flexible material (sealant or foam strip)
- Width: 10-15 mm
- The joint runs the full height of the wall
In concrete floors
- Saw cut — After pouring, a groove is sawn (1/3 of floor thickness), causing the concrete to crack at a controlled point
- Profile — A metal or plastic profile cast into the floor
In tiled floors
- A flexible joint (silicone sealant) instead of rigid grout
- Expansion profile of aluminium or plastic for a neat finish
Common mistakes
- Forgetting expansion joints — Cracking is inevitable in large surfaces
- Filling expansion joints with rigid grout — The joint must stay flexible, otherwise cracks appear next to it
- Too few joints — Large terraces or floors need expansion joints every 5-6 m
- Joint not continuous — An expansion joint must run from top to bottom, not stop halfway
Related terms
- Bond pattern
- Foundation
- Tiles
- Concrete slab
- Facade
- Mortar joints