CON/General/TBT-CON-004

Formwork Erection and Striking

Concrete & Formwork › General › Formwork Erection and Striking

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Formwork is the temporary mould that shapes wet concrete into the designed structural elements during construction.
Formwork erection involves assembling panels, props, beams, and bracing into a system capable of supporting wet concrete loads.
A permit to load must be issued by the temporary works coordinator before any concrete is placed into the formwork.
Wet concrete exerts lateral pressure on vertical formwork — inadequate bracing or tie spacing causes formwork blowouts.
Striking means removing formwork after the concrete has hardened — premature striking before adequate strength causes collapse.
Cube test results must confirm the concrete has reached the required strength before the TW coordinator authorises striking.
The striking sequence must follow the designed order — random removal creates dangerous load concentrations and instability.
Formwork components are heavy and awkward — mechanical lifting and team handling are required during erection and striking.
Release agent must be applied to formwork faces before reinforcement is fixed to ensure clean, damage-free stripping.
Formwork panels must be inspected for damage, warping, and cleanliness before reuse on subsequent pours.

Blowout risk	Inadequate formwork bracing or tie spacing fails under the pressure of wet concrete, causing a sudden, violent blowout.
Premature striking	Removing formwork before concrete is strong enough causes structural collapse — only cube test results confirm readiness.
Correct sequence	Striking out of order concentrates loads on remaining supports, exceeding their capacity and causing progressive failure.

Don't

Erect formwork exactly as shown on the approved design drawings and specification.
Obtain a permit to load before placing any concrete into the formwork system.
Check formwork tie spacing and bracing are correct before the pour begins.
Apply release agent to formwork faces before fixing reinforcement inside.
Monitor formwork during the pour for signs of movement, leakage, or deflection.
Wait for cube test results before requesting authorisation to begin striking.
Follow the designed striking sequence — do not remove formwork in random order.
Use mechanical lifting for heavy formwork panels during erection and striking.
Inspect all formwork panels for damage and warping before reuse.
Brief the team on the formwork system, pour sequence, and striking schedule.

DON'T alter the formwork design on site without engineer approval.
DON'T pour concrete without a valid permit to load from the TW coordinator.
DON'T accept inadequate tie spacing or bracing — check before the pour starts.
DON'T omit release agent — formwork without it damages the concrete on striking.
DON'T ignore leaking, bulging, or deflecting formwork during a pour — stop and investigate.
DON'T strike formwork until cube tests confirm the concrete strength is adequate.
DON'T remove formwork panels out of the approved striking sequence.
DON'T manually lift heavy formwork components when mechanical aids are available.
DON'T reuse formwork that is damaged, warped, or no longer fit for purpose.
DON'T skip the formwork briefing — the team must understand the system and schedule.

See also: Formwork and Falsework | Concrete Pour Safety

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