Temporary Works and Formwork: Design-Risk Considerations
Temporary works — and proprietary table formwork in particular — carry design risks that are easy to underestimate because the structure is meant to be short-lived. The considerations below draw on Ministry of Manpower (MOM) safety guidance on proprietary table formwork.
Temporary works fail most often during erection, lifting, repositioning and dismantling — not while sitting in its final, braced position. Design-risk review for temporary works needs to look at the whole sequence of work, not just the finished condition.
Key hazards to consider
Instability during erection, lifting & repositioning
Formwork is at its most vulnerable while being rigged, lifted or repositioned — not once it is fully installed and braced.
Work-at-height risk
Personnel rigging and unrigging lifting gear, or working at table-formwork edges, face fall risk that the design and method should address together.
Site constraints & unsuitable supporting conditions
Obstructions, uneven ground or unsound supporting elements at a specific site can undermine a design that would otherwise be adequate.
Manufacturer requirements & limitations
Proprietary formwork systems carry manufacturer limits — including height-to-breadth ratio — that the design and method statement must respect.
Sequence, bracing and lifting
Method & sequence of work
The order in which formwork is erected, struck, repositioned and re-erected materially affects stability — the design should assume a specific sequence, not just a finished state.
Bracing, tie-backs & unbalanced forces
All bracing and tie-backs necessary for strength and stability against unbalanced forces should be shown on the formwork drawings, not left to site judgement.
Lifting points & load eccentricity
Lifting points should be positioned to avoid tilting the load during lifts, with clearance checked against surrounding structure and plant.
Height-to-breadth limitations
Height-to-breadth ratio limits for tower table formwork, as set by the manufacturer, should be respected and reflected in design documentation.
MOM safety guidance has called for proprietary table-formwork structures to be designed for a minimum factor of safety of 2.0 for strength and stability under the most adverse applicable loads and load combinations. This figure applies specifically to proprietary table formwork as addressed in that guidance — it should not be assumed to apply automatically to other structures or to every DfS assessment. Confirm the current, applicable design standard for each specific temporary works element.
Proprietary and non-proprietary elements together
Where proprietary formwork interfaces with site-fabricated or non-proprietary elements, the design should consider the complete assembly, not each part in isolation.
Design deviations
Any deviation from a manufacturer's standard configuration should be reviewed by an appropriately qualified designer or Professional Engineer before use.
Why temporary works designers should attend DfS reviews
Temporary works are often designed by a specialist engaged by the Contractor, separately from the permanent works design team. Where a temporary works design creates or controls a material risk — as formwork, falsework, shoring or access scaffolding often do — the temporary works designer should participate directly in the relevant DfS review, rather than being represented secondhand by the main Contractor. This keeps residual risks specific to the temporary works properly recorded and communicated, including in the recording and communication of residual risks within the DfS Register.
Reviewing a temporary works or formwork design?
Tell us the system and stage of works, and we will confirm what a DfS review of the temporary works should cover.