There is no single person who automatically owns every temporary-works duty. The organisation controlling the construction phase must establish a suitable management process; competent designers produce the design; checks are arranged at a level proportionate to the risk; site teams install and use the works to the accepted design; and a named coordinator is commonly appointed to control the interfaces and authorisations.
On a project with more than one contractor, the Principal Contractor has the CDM duty to plan, manage, monitor and coordinate the construction phase. That duty is not transferred merely by appointing a Temporary Works Coordinator (TWC), a specialist subcontractor or an engineer. On a single-contractor project, the contractor must make suitable arrangements for its work.
HSE states that the law does not prescribe one specific way to manage temporary works and does not require the exact job title “Temporary Works Coordinator”. The arrangement must nevertheless be suitable for the project and control the work from concept through removal.
What counts as temporary works?
Temporary works are engineered solutions used to support or protect a structure, plant, equipment, people or an excavation while permanent work is built, altered, maintained or demolished. HSE examples include:
- earthworks, trenches, excavations, stockpiles and temporary slopes;
- shoring, propping, needling, falsework, formwork and access scaffolds;
- haul roads, working platforms and crane or piling mats;
- hoardings, fencing, site-office and welfare-unit foundations;
- temporary supports for existing or partially completed structures; and
- parts of the permanent works used in a temporary condition during the sequence.
The last category is easily missed. A permanent slab, frame or wall may experience temporary loads, incomplete restraint or a different load path before the final structure is complete. The construction sequence and temporary condition therefore need to be considered, not just the finished design.
Who holds the legal responsibility?
The Construction (Design and Management) Regulations 2015 place duties on several parties. Their responsibilities overlap, but they are not interchangeable.
| Role | Relevant responsibility | What the appointment does not remove |
|---|---|---|
| Client | Make suitable project-management arrangements, allow sufficient time and resources, and appoint capable duty holders where required. | The client should not assume that a contractor price automatically includes every necessary design, check or specialist input. |
| Principal Designer | Plan, manage, monitor and coordinate health and safety in the pre-construction phase, including foreseeable design and sequence risks, and liaise with the Principal Contractor. | The CDM Principal Designer is not automatically the temporary-works designer or TWC. |
| Principal Contractor | Plan, manage, monitor and coordinate the construction phase and ensure suitable arrangements are implemented across contractors. | Appointment of a TWC, designer or specialist subcontractor does not transfer the Principal Contractor's overall CDM management duty. |
| Contractor | Plan, manage and monitor its work, provide competent people and information, follow the agreed controls and report changes or defects. | A subcontractor remains responsible for managing the work under its control and coordinating with others. |
| Temporary-works designer | Prepare a design based on a clear brief, site information, loading, interfaces, sequence and stated assumptions. | Producing calculations does not by itself coordinate procurement, design checks, site release, inspection or dismantling. |
| Temporary Works Coordinator | Coordinate the agreed procedure, register, briefs, designs, checks, site implementation, hold points and permits or releases. | The TWC should have authority and resources, but does not absorb every duty held by the client, designers, Principal Contractor and contractors. |
Is a Temporary Works Coordinator legally required?
HSE says there is no specific legal requirement to use the title TWC or to follow one prescribed management method. It also says that appointing a TWC is an effective way to manage temporary works, particularly on medium and large projects. Simpler projects may use a less formal arrangement, but the temporary works must still be properly designed, installed, used, inspected and removed.
Where a TWC is used, HSE recommends a formal appointment. The person needs sufficient competence for the project's complexity, a clear reporting line, adequate time and authority—including authority to stop work if arrangements are unsatisfactory.
The TWC does not have to be the engineer who designed the works. HSE specifically notes that the engineer is not automatically the TWC. Coordination is broader than calculation: it covers interfaces between design, checking, procurement, programme, ground conditions, installation, loading, inspection and dismantling.
How should the designer, checker and site team work together?
A usable temporary-works design starts with a controlled brief. The brief should describe the purpose, geometry, sequence, loads, ground and existing-structure information, site constraints, interfaces, design life, standards or proprietary systems, erection and dismantling needs and any required hold points.
The designer should state the assumptions and limitations clearly. A proportionate check should then be completed before the design is released for use. HSE says that, except for the simplest cases, a temporary-works design and relevant calculations will be needed and that more complex designs may require independent checking.
The site team must receive the accepted information in a form it can build and inspect. If site conditions differ from the design assumptions, the correct response is to stop, record the difference and obtain a reviewed solution—not to improvise or mark up a drawing without authority.
What should a controlled temporary-works process include?
- Identify and register: capture each item early, including temporary conditions within the permanent works, and assign an owner and status.
- Define the brief: record the purpose, sequence, inputs, loads, constraints, interfaces and acceptance criteria.
- Appoint competent people: confirm who coordinates, designs, checks, installs, inspects and authorises each stage.
- Design and check: produce an appropriate design and complete the agreed check before issue for construction.
- Communicate and build: issue the current information, brief the workforce and install to the accepted design and manufacturer requirements.
- Inspect and release: verify the installed condition and use a permit or other controlled release where the risk and procedure require one.
- Monitor and control change: inspect during use, protect against unauthorised alteration or overloading and refer departures back for review.
- Dismantle and close: plan safe removal or striking, confirm the permanent works can accept the load, record completion and close the register item.
The level of documentation should be proportionate. The law does not mandate one universal form for every item, but a register, controlled briefs, design and check records, inspection evidence and clear releases help teams demonstrate which version was accepted and whether each hold point was passed.
Do standard solutions or proprietary systems remove the need for design control?
No. HSE says standard solutions may be used, but the assumptions and limitations must be checked against the actual site. A standard detail prepared for different ground, loads, dimensions, wind exposure, restraint or construction sequence may not be suitable.
Proprietary systems such as formwork, falsework, trench supports or proprietary edge protection must be selected and used within the manufacturer's instructions. Those instructions need to be available to the people installing and inspecting the system. Mixed components, non-standard configurations, altered loadings or departures from the instructions should be referred for competent review.
What should happen during inspections or when conditions change?
Temporary works should be inspected at the stages identified by the design and management procedure. Relevant triggers can include completion of installation, before loading or pouring, after alteration, after severe weather or impact, during continued use and before dismantling or striking.
An inspection should compare the installed condition with the current accepted design. It may need to confirm dimensions, levels, foundations or bearing, bracing, ties, connections, components, exclusion zones, loading limits and signs of movement or damage.
A general site inspection can identify visible management or condition issues, but it does not automatically replace a design-specific temporary-works inspection or authorisation. Similarly, a Construction Phase Plan should describe the management arrangements, while the detailed register, briefs, designs, checks and releases remain controlled supporting records.
What should a client or contractor ask before work starts?
- Which temporary works and temporary structural conditions have been identified?
- Who controls the process, and is their authority clear?
- Is there a current register showing the status of each item?
- Are design briefs complete, including ground, loading, sequence and interface information?
- Who designs and checks each item, and is the checking approach proportionate to complexity?
- How are current drawings, calculations, assumptions and manufacturer instructions issued to site?
- What must be inspected, released or permitted before loading, use, pouring, striking or dismantling?
- How will design changes, site departures, damage and adverse weather be controlled?
A named coordinator cannot compensate for missing briefs, unreviewed changes, unclear authority or inadequate time. The evidence should show how decisions move from identification and design to safe installation, use and removal.