Kicker formwork is the shuttering used to cast a kicker: a low concrete upstand on the floor slab, exactly on the line and to the thickness of the wall that will follow. Once that kicker has hardened it forms the clamping face and starting point for the wall formwork. In in-situ concrete work this is a standard step in building concrete walls.
The kicker itself is only a few centimetres high — but it decides whether the whole wall ends up straight, to size and in the right place.
Why cast a kicker?
- An exactly level starting point — the top is screeded off level, so the remaining wall height is the same everywhere
- It fixes the position — the kicker sits on the set-out wall line, so the formwork cannot slide off it
- It stops grout loss — no concrete can escape at the bottom of the formwork, which avoids honeycombing and grout runs at the wall foot
- It guarantees the wall thickness — the kicker is the same thickness as the wall and acts as a template for the joint
How it is done
- Set out — mark the wall lines on the cast slab (string line, laser)
- Set the kicker formwork — two boards, battens or steel profiles at the wall thickness, fixed down to the slab
- Pour and screed — fill the kicker and screed the top off level
- Strike — remove the shuttering once cured; the kicker stays
- Set the wall formwork — clamp the panels against the kicker and prop them
Alternative and points to watch
- Formwork base anchors — instead of casting a kicker you can press base anchors into the fresh slab; they then act as spacer and starting point, saving a pour and a strike
- Bond — hand over the slab surface clean and roughened where the kicker goes; a dirty or smooth substrate gives a leaking joint
- Reinforcement — leave the starter bars from the slab standing free and cast the kicker around them, not over them
- The wall-floor joint stays a weak point — the horizontal construction joint between slab, kicker and wall is where water gets in on basements and water-retaining structures; that is where a waterbar such as a swelling strip or metal waterstop belongs
Related terms
- Formwork base anchor
- Wall-floor joint
- Metal waterstop
- Formwork
- In-situ concrete
- Concrete floor
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