7.2 Formwork and Falsework: Temporary Works Design, Erection, Inspection and Loading
Key Takeaways
CDM 2024 regulation 21(2) requires temporary supports and temporary structures such as falsework to be designed, installed and maintained to withstand foreseeable loads, and to be used only for the purpose for which they were designed.
The collapse of any temporary support in a building or structure under construction is a dangerous occurrence under NADOPOD 2004 and must be notified to DOSH immediately.
The repealed BOWEC regulation 30 required Professional Engineer design of formwork where floor-to-ceiling height exceeded 9.14 metres, where shores were in two or more tiers, or where loads exceeded 732.2 kgf per square metre.
The repealed BOWEC regulation 29 required a designated person to supervise formwork erection, inspect it after erection and during concrete placing, and keep inspection records on site.
Fresh normal-weight reinforced concrete weighs roughly 24–25 kN per cubic metre, so a 300 mm slab imposes about 7.5 kN/m² before construction loads are added.
Formwork and falsework: two jobs
| Formwork | Falsework | |
|---|---|---|
| What it is | The mould that holds wet concrete to shape: plywood, panels, column boxes, tie rods | The temporary structure that supports the formwork, the concrete and the construction loads until the permanent structure can carry itself |
| Main loads | Lateral pressure of fluid concrete on walls and columns; self-weight | Vertical loads from concrete, reinforcement, formwork, people and plant; horizontal loads from wind, pumping surges and out-of-plumb props |
| Typical failures | Ties or clamps fail and a wall "blows out"; panel deflection | Prop buckling; base settlement; missing bracing; overloading during the pour |
Concrete is heavy. Normal-weight reinforced concrete is about 24–25 kN/m³, so a 300 mm slab imposes roughly 0.3 x 25 = 7.5 kN/m² of dead load before formwork, people, plant and the surge from pumping are added. Transfer plates and deep beams multiply this.
The law
- CDM 2024 regulation 21(2): any support, temporary support or temporary structure must be designed, installed and maintained to withstand any foreseeable load, and used for the purpose for which it was designed. Regulation 21(3): no structure may be loaded so as to become unsafe. Most breaches carry up to RM500,000 or one year or both.
- OSHA 1994 sections 15, 18A and 18B: safe systems of work; a principal's duty to provide sufficient time, budget and resources, which matters when programme pressure pushes early stripping; and an implemented risk assessment.
- NADOPOD 2004, Second Schedule Part I item 2: collapse or partial collapse of any part of a building or structure under construction, or of any temporary support, is a dangerous occurrence, unless the collapse was intended.
What the repealed BOWEC Part III said
BOWEC (repealed 1 June 2024) had detailed concrete-work rules that still appear in older notes and are useful benchmarks:
| BOWEC reg. | Rule |
|---|---|
| 28 | Formwork and reshores certified structurally safe by a Professional Engineer and braced or tied to keep position and shape; multi-tier formwork to have catwalks for inspection |
| 29 | A designated person supervises erection, inspects after erection and during concrete placing, has unsafe conditions remedied immediately, and keeps inspection records on site |
| 30 | Horizontal and diagonal bracing in both directions; shores seated and secured top and bottom; base plates on ground. PE design where floor-to-ceiling height exceeds 9.14 m, shores are in two or more tiers, or loads exceed 732.2 kgf/m²; the PE supervises construction |
| 31 | No stripping until the concrete is set to the PE's specification and the PE approves; stripped forms cleared promptly; protruding nails and ties removed |
| 32 | Reshoring where needed to support slabs and beams after stripping or under loads from construction above |
A temporary works control process
The British code BS 5975 (temporary works procedures and falsework design) is widely used on Malaysian projects. Under CDM 2024 the following process puts regulation 21 into practice:
- Design brief: loads, pour sequence, ground or supporting slab capacity, and programme.
- Design by a competent designer. Proprietary systems follow the supplier's design. Bespoke, tall, heavily loaded or multi-tier falsework needs a Professional Engineer's design.
- Independent design check, scaled to the complexity and risk.
- Erection by competent erectors to the drawings, supervised.
- Inspection before loading against the drawings, by the temporary works coordinator or designated person.
- Permit to load (or permit to pour) issued only when the inspection is satisfactory.
- Monitoring during the pour by a nominated person with authority to stop the pour.
- Permit to strike only when the designer's or engineer's criteria, such as cube strength or age, are met.
- Back-propping and reshoring as designed for loads from floors above.
The construction phase plan (CDM regulation 13) should name who coordinates temporary works and how permits are issued.
Falsework details the SSS checks
| Item | What to look for |
|---|---|
| Foundation | Props on base plates and sole plates on compacted ground or on a slab checked for the load; never on loose bricks, blocks or offcuts; drainage |
| Props | Correct type and size, as on the drawing; inner and outer tubes within the extension range; manufacturer's pins, never rebar, nails or bolts; plumb (BS 5975 practice limits adjustable props to about 1.5° from vertical); heads and bases fixed |
| Load-bearing towers and frames | Jacks within their extension limits; frames complete; all locks engaged |
| Bracing | Plan and diagonal bracing in both directions as designed; nothing removed for access |
| Heads and bearers | Forkheads or U-heads centred; primary and secondary beams at the designed spacing; no unbraced cantilevers |
| Formwork | Correct panel thickness; ties and clamps at the designed spacing; joints tight; edge forms secure |
| Access and edges | Working platforms and guardrails at slab edges (Chapter 4); safe access for steel fixers and concreters |
| Records | Drawings on site; inspection record; permit to load signed |
Warning signs during a pour
Concreting must stop at once if anyone sees:
- props bending, kicking out or punching into the ground
- forms bulging or ties stretching
- the deck sagging more than expected
- cracking or creaking noises
- concrete heaped in one place
The pour sequence should spread the load evenly as the design requires. A watcher stays below or beside the deck, at a safe position outside the collapse zone, to look for these signs. The watcher has the authority to stop pumping.
Stripping and reshoring
- Strip only with authority. Stripping before the concrete reaches its specified strength, often under programme pressure, has caused slab and beam failures. Strike only under a permit-to-strike based on the designer's criteria, such as cube results.
- Back-props and reshores are designed to carry loads from floors cast above. Install them as specified, and do not remove them early.
- During stripping: strip in a controlled sequence; keep people out of the drop zone below; and lower formwork, never drop it.
- After stripping: clear stripped materials promptly from walkways, and remove or flatten nails and ties (CDM regulation 20).
Scenario: the 5-metre transfer slab
The night before a transfer slab pour, the SSS finds:
- 3 m props extended to their limit and stacked on timber blocks to reach 5.2 m
- no bracing in one direction
- no drawings on site
The subcontractor says it "always does it this way". The SSS:
- Refuses the permit to pour and informs the project manager. The falsework does not meet CDM regulation 21, and an unsafe pour risks a collapse that would be a NADOPOD dangerous occurrence.
- Has the pour postponed and the concrete order cancelled. The principal contractor's temporary works coordinator obtains a design for the actual height and load: heavy-duty shoring towers with bracing, checked by an independent engineer.
- Arranges for the falsework to be rebuilt to the design, inspected, and a permit to load issued. A watcher is appointed for the pour.
- Records the event as a near miss and briefs the lesson to all formwork crews.
Which CDM 2024 regulation requires falsework to be designed, installed and maintained to withstand any foreseeable load?
Regulation 8
Regulation 21
Regulation 28
Regulation 37
Falsework supporting a slab collapses during a pour, but no one is injured. How is this treated under NADOPOD 2004?
As a near miss, to be recorded only in the site diary and toolbox minutes
As an occupational disease to be reported on the JKKP 7 form
As a dangerous occurrence, because a temporary support has collapsed
As a commercial matter for the concrete supplier and formwork subcontractor
What did the repealed BOWEC regulation 29 require for formwork?
Inspection only once the stripping is complete
A yearly inspection by DOSH before any pour
Inspection only by the concrete supplier when the first truck is delivered
Supervised erection, plus inspection after erection and during the pour
Sections you finish are checked off in the contents.