What is a cast-in socket?
A cast-in socket is a threaded sleeve that is left in the concrete during pouring (cast in). Once the concrete has hardened, there is a clean threaded hole in which a bolt or threaded rod can later be screwed. This lets you fix something to the concrete without drilling and plugging afterwards. It is also called a cast-in ferrule or anchor socket.
Application
Cast-in sockets are common in concrete and precast work:
- Lifting anchors — sockets are cast into precast elements (walls, floors, stairs) so they can be lifted safely.
- Fixing points — for the later mounting of facade elements, handrails, machines, cable trays or suspension systems.
- Temporary anchors — for example props, fall protection or scaffolding during construction.
Points to watch
The position of the socket is fixed to the formwork or the reinforcement before pouring, so it stays in the right place and square. Note:
- Load capacity — choose the type and size to suit the manufacturer’s stated tensile and shear load; never exceed the permitted load.
- Concrete cover — keep enough edge distance, or the concrete will break out.
- Corrosion — outdoors or in a damp environment, use a galvanised or stainless version.
Always work to the manufacturer’s fitting instructions and load tables; a cast-in socket is a structural fixing on which safety depends.
Related terms
- Concrete
- Chemical anchor
- Formwork
- Reinforcement
- Concrete cover
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