What is a starter bar?
A starter bar is a reinforcing bar deliberately left projecting from a concrete element so that the next element, cast or fixed later, can be structurally tied to it. Typical examples are bars sticking up out of a foundation for the wall above, or out of a pile head into the ground slab. They are also called dowel bars or projecting reinforcement. The Dutch term is stekeind (or simply stek).
Ways to make the connection
- Lap splice: the new bars overlap the starter bars and are tied with wire. The lap length comes from the structural design (in Europe, Eurocode 2).
- Threaded coupler: the starter bar has a thread or coupler, and a second bar is screwed on later. This avoids long bars poking through the formwork.
- Rebend system: bars are cast bent flat inside a steel box and straightened after the formwork is struck (see reinforcement continuity box).
Application
- Follow the reinforcement drawing. Number, diameter, length and position of starter bars are set by the structural engineer.
- Fix them before the pour. Tie starter bars to the main reinforcement so they do not move during placing and vibrating.
- Protect threads. Fit caps on threaded ends so no concrete or rust gets in.
- Cap exposed ends. Projecting bars are sharp and hard to see. Brightly coloured protective caps reduce the risk of cuts and impalement; site safety rules in most countries require such hazards to be guarded.
- Prepare the joint. Clean and, where specified, roughen the construction joint before the next pour.
Common mistake: cutting off or bending over starter bars because they are “in the way”. That removes the structural link to the next element; always check with the engineer first.
Related terms
- Reinforcement
- Reinforcing steel
- Supplementary reinforcement
- Concrete cover
- Construction joint
- Reinforcement continuity box
- Formwork
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