Read through the reports from serious temporary works failures and a pattern emerges that has very little to do with engineering.
A design brief that never reached the designer. An inspection signed before the work was complete. A revision superseded but not withdrawn from site. A verbal instruction that changed the sequence and never made it onto paper.
The calculations were usually fine. What failed was the process around them — and that process is what the Temporary Works Coordinator exists to hold together.
This article sets out what the TWC role actually involves, how it differs from the TWS, how BS 5975 procedures work in practice, and where they break down.
Before the role makes sense, the scope has to be clear — and this is where sites lose things.
Temporary works are the parts of a project that support, protect or provide access during construction and are then removed. A propped wall is obvious. So is falsework, and formwork, and a scaffold.
What gets missed is everything else:
The test is functional, not visual. If it is holding something up, holding something back, or providing access, and it is coming out later, it is temporary works. The risk does not depend on whether anyone classified it correctly.
BS 5975 sets out procedural control for temporary works alongside permissible stress design of falsework. The procedural side defines a set of roles, and the distinctions between them matter.
A senior person within the organisation who is accountable for the temporary works procedure being in place and being followed. They appoint the Temporary Works Coordinator. This is a corporate accountability role rather than a site delivery one.
The person responsible for coordinating all temporary works activities on a project. The TWC does not necessarily design anything and does not necessarily check anything. What they do is ensure that the process runs end to end: that briefs are produced, designs are obtained, checks are carried out at the right category, correct information reaches site, works are inspected, and loading and striking are formally permitted.
The TWC role is one of custody. The chain runs:
…and the TWC owns that chain.
Where a project is large enough, TWSs support the TWC by supervising specific temporary works on the ground. The TWS reports to the TWC and typically handles day-to-day supervision, inspection and compliance for their allocated works.
The distinction people get wrong: the TWS is a supervision role, not a junior coordinator. Appointing TWSs does not divide the TWC's accountability; it extends their reach.
The designer produces the design against the brief. The checker verifies it, with the required independence set by the design check category.
BS 5975 categorises design checks according to the complexity and consequence of the temporary works. The principle is straightforward: the more that could go wrong, the more independent the person checking must be.
In broad terms the categories run from standard solutions applied within established parameters, through simple designs, to more complex designs, and finally to complex or innovative work requiring a check by an organisation independent of the designer's.
The specific definitions and the independence required at each level are set out in the standard, and any procedure should reference it directly rather than relying on recollection.
Two practical points.
The categorisation decision is quietly one of the most important on the project. It is usually made early, quickly, and by whoever is writing the brief. Set it too low and you have decided — without noticing — that the riskiest structure on site receives the least scrutiny.
Category and complexity are not the same as size. A small, unusual, highly consequential temporary structure can warrant more independence than a large, standard, well-understood one.
Most of the failures traced back to process failure begin here.
The brief is the document that tells the designer what they are designing, under what constraints, for what loads, in what sequence, and with what interfaces. A brief that says “design a prop for the opening” is not a brief.
A usable brief covers:
If the designer has to guess at any of these, the brief has moved the risk rather than resolved it.
The register is the dullest document on any site and the one everyone wants to read the moment something moves.
It lists every temporary works item on the project with its reference, current revision, design check category, status, and the permits issued against it. Live, struck, still carrying load — the register should answer all of those without anyone having to ask around.
Two failure modes are common. The register exists but is not current, so it describes a site that stopped existing three weeks ago. Or the register is current but incomplete, because the site road and the outrigger mats were never recognised as temporary works in the first place.
A city centre basement, three levels down, secant piled wall, propped as the excavation progresses, slabs cast bottom-up afterwards.
The temporary works on that job include the piled wall in its temporary condition, every stage of propping, the crane base, the working platform, the site road, the access stair, the hoarding, and the dewatering system.
The TWC's problem is not any single design. It is that these interact.
The propping design assumes a specific excavation sequence. The excavation sequence assumes the crane can reach. The crane base assumes a platform that assumes ground conditions. The dewatering assumes a duration that assumes the programme.
Change the excavation sequence to recover two weeks — a perfectly reasonable commercial decision made in a progress meeting — and you have potentially invalidated the propping design, altered the wall's governing load case, and extended the dewatering period.
Nobody in that meeting was thinking about temporary works. That is exactly why the coordination role exists, and why the TWC needs to be in the room where sequence decisions are made rather than being told afterwards.
Appointing a TWC without authority. A coordinator who cannot stop work has a title, not a role. If the TWC's permit to load can be overruled by programme pressure, the procedure is decorative.
Treating the TWC as a design role. The TWC coordinates. Where they also design, the independence required for checking still applies — they cannot check their own work.
Missing items from the register. Site roads, mats, temporary propping and access structures are the usual omissions.
Weak briefs. The single most common root cause. A designer working from an incomplete brief produces a design for a problem that may not be the one on site.
Not withdrawing superseded drawings. Issuing revision C is only half the task. Revision B has to physically leave site.
No permit discipline. Loading before the inspection is complete, or striking on a verbal instruction, defeats the whole chain.
Ignoring change. Almost every temporary works incident involves a change nobody re-checked — different plant, altered sequence, deeper excavation, new surcharge near a wall or slope.
The TWC coordinates all temporary works on a project — ensuring design briefs are produced, designs obtained and checked at the correct category, correct information issued to site, works inspected, and loading and striking formally permitted. It is a coordination and control role rather than a design role.
The TWC coordinates the whole temporary works process across the project. TWSs support the TWC by supervising specific temporary works on the ground, reporting to the TWC. Appointing TWSs extends the coordinator's reach; it does not divide their accountability.
There is no statute naming the role. However, CDM 2015 places duties on Principal Contractors to plan, manage and monitor construction work, and BS 5975 provides the recognised procedural framework for discharging those duties for temporary works. In practice, appointing a TWC is the industry-standard way of demonstrating adequate control.
There is no single mandatory qualification. Competence is the requirement — relevant engineering knowledge, sufficient experience of the type of works involved, and the authority to act. CITB-accredited TWC training is widely used and commonly expected by clients and principal contractors.
They are a set of categories that scale the independence of the design check to the complexity and consequence of the temporary works, from standard solutions through to complex or innovative designs requiring a check by an independent organisation. The definitions sit in the standard and should be referenced directly.
Every temporary works item on the project, with its reference, current revision, design check category, current status, and associated permits. It should be possible to tell from the register alone what is live, what has been struck, and what is still carrying load.
Responsibility is distributed under CDM 2015 across client, designer, principal contractor and contractor, with duties also falling on individuals. Following BS 5975 procedures does not remove liability, but it demonstrates the control that duty holders are expected to exercise.
No — the level of check scales with the assigned category. Simple, standard items require less independence than complex or high-consequence designs. The judgement lies in categorising honestly, because under-categorising is a decision to reduce scrutiny.
The Temporary Works Coordinator role exists because temporary works fail through process far more often than through calculation.
The engineering is usually competent. What breaks is the chain around it — the brief that was too thin, the category set too low, the drawing that was superseded but not withdrawn, the sequence change nobody fed back into the design.
Define the scope broadly, write proper briefs, categorise checks honestly, keep the register live, control document issue, and use permits as decisions rather than paperwork.
And give the coordinator the authority to stop work. A procedure that cannot halt a pour is not a control measure.
LMT.Pro runs the BS 5975 calculations and produces the design brief, calculation report, risk assessment, inspection checklist and RAMS — ready to issue.
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