Wire mesh formwork is a lightweight, often permanent formwork made of steel mesh or expanded metal, used to hold back fresh concrete or to close off a construction joint. The mesh remains in the concrete after pouring and creates a rough surface for bonding with the next pour.
How does it work?
In large concrete elements, the concrete is placed in stages. Between two pours, a construction joint is formed. To close that joint neatly, a wire mesh is fitted:
- The mesh holds back the fresh concrete
- Reinforcement runs through the mesh
- The rough surface left behind bonds well with the next pour
- The mesh is not removed — hence ‘permanent’ or ‘lost’ formwork
Advantages
- Lightweight — easy to place and cut
- Permeable — excess water can escape, and reinforcement can pass through
- Rough joint interface — gives a better bond than a smooth formwork joint
- Inexpensive — a simple material and quick to install
- No stripping — it stays in place
Applications
Wire mesh formwork is used for:
- Vertical construction joints in walls and columns
- Large slab fields — to allow staged casting
- Joint closure with continuous reinforcement
- Combined with expansion joint profiles
- Foundation blocks in stages — for large volumes
Points to watch
- Adequate mesh strength — it must resist the pressure of fresh concrete
- Proper support — braced with props or battens
- Tight connection to edge formwork — to prevent honeycombing
- Reinforcement clearance — enough space for the rebars to pass
Related terms
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