Temporary works in construction: BS 5975, the TWC role, and the permit process

What are temporary works?

Temporary works are any engineering structures or procedures that are required during construction but do not form part of the completed building or infrastructure. They carry loads, provide support, or enable access while permanent works are being built. Common examples include:

• Formwork and falsework: Moulds and supporting structures for in-situ concrete. Falsework supports the formwork until the concrete has gained enough strength to be self-supporting.
• Scaffolding: Access scaffolding for working at height, and support scaffolding (such as birdcage scaffolds) for temporary loading.
• Propping and shoring: Temporary supports for existing structures during demolition, alteration, or underpinning.
• Excavation support: Sheet piling, trench boxes, and other systems to prevent collapse of excavation walls.
• Temporary bridges and access roads: Structures to allow plant and personnel to cross excavations, watercourses, or other obstacles.
• Cofferdams: Watertight enclosures pumped dry to allow construction below water level.

The defining characteristic of temporary works is that they must be designed, checked, and managed with the same rigour as permanent structures. The loads they carry are real, and the consequences of failure are just as severe.

BS 5975 and the legal framework

BS 5975: Code of Practice for Temporary Works Procedures and the Permissible Stress Design of Falsework is the industry standard for managing temporary works. While it is a code of practice rather than a legal requirement in itself, it provides the framework that is almost universally adopted for meeting legal duties under:

• CDM 2015: Requires that all work, including temporary works, is planned, managed, and monitored to ensure it is carried out safely. The principal contractor must ensure coordination between contractors whose temporary works may interact.
• Health and Safety at Work Act 1974: The general duty to ensure the health and safety of employees and others affected by the work.
• Work at Height Regulations 2005: Applies to scaffolding and any temporary works that involve work at height.

HSE investigators and courts routinely reference BS 5975 when assessing whether a contractor has met their legal obligations. Not following BS 5975 does not automatically mean a breach of the law, but it is very difficult to defend a temporary works failure if you cannot show that you followed an equivalent or better standard.

The Temporary Works Coordinator role

The TWC is the linchpin of the BS 5975 system. Their responsibilities include:

• Maintaining the temporary works register: A log of all temporary works on the project, their status (designed, checked, erected, loaded, dismantled), and the responsible persons.
• Ensuring designs are produced and checked: Every temporary works item must have a design, and that design must be independently checked before the structure is built. The TWC ensures this happens.
• Issuing permits to load: Before any load is applied to a temporary works structure (such as pouring concrete onto formwork), the TWC must confirm that the structure has been erected correctly and issue a permit to load.
• Inspecting temporary works: Regular inspections during the life of the temporary structure to ensure it remains in the condition assumed by the design.
• Managing dismantling: Temporary works must not be removed until the permanent works can safely carry the loads. The TWC must confirm when dismantling can proceed.

The TWC must be competent, which means they need appropriate training, knowledge, and experience. On smaller projects, the site manager may act as TWC. On larger projects, the TWC is typically a dedicated role. CITB and other providers offer TWC training courses, usually lasting 2 days.

A common problem is appointing a TWC who does not have the time or authority to carry out the role effectively. The TWC must be able to stop work if they believe a temporary works structure is not safe. This requires both competence and organisational support.

Design and design check

BS 5975 requires that temporary works are designed by a competent person and independently checked by a separate competent person (the design checker). This is not a rubber-stamping exercise. The design checker must independently verify that:

• The design assumptions (loads, ground conditions, interfaces with permanent works) are correct.
• The calculations are accurate.
• The proposed materials and components are suitable.
• The design can be safely erected and dismantled.

For standard items like scaffolding and simple propping, the "design" may be a compliance check against manufacturer's guidance and load tables rather than a bespoke calculation. But the checking process still applies.

The design and the design check must both be completed and signed off before any temporary works are erected. This is a hard gate. Pressures to "get on with it" and check the design afterwards are a recurring cause of temporary works failures.

The permit to load process

The permit to load is a formal, documented confirmation that a temporary works structure has been erected in accordance with the design and is safe to receive the intended load. The process is:

1. Erection: The temporary works are built by competent personnel in accordance with the approved design.
2. Inspection: The TWC (or their delegate) inspects the erected structure against the design drawings. Any deviations are flagged and resolved.
3. Permit issued: If the inspection confirms that the structure matches the design, the TWC issues the permit to load. This is a signed document specifying what loads can be applied and any conditions.
4. Loading: The load is applied (concrete poured, materials stacked, equipment placed) only after the permit is in place.

The permit to load is similar in concept to a permit to work. It is a formal control that prevents a critical activity (applying load) from happening until a competent person has confirmed it is safe to do so.

Managing permits on paper works on small projects but becomes difficult on large sites with dozens of temporary works items at different stages. Digital permit systems that track each item through its lifecycle, from design to dismantling, with timestamped sign-offs at each stage, provide a clearer audit trail and make it harder for steps to be skipped.

Common failures and how to prevent them

HSE investigations into temporary works failures consistently identify the same root causes:

• No design or design check: Temporary works erected based on "experience" without any formal design. This is the most dangerous failure mode.
• Design assumptions not matched on site: The design assumed firm ground, but the actual conditions are soft clay. The design assumed a specific propping layout, but the site team modified it to work around an obstruction.
• Permit to load not issued: Concrete poured onto formwork before the TWC has inspected and signed off. Time pressure is usually the stated reason.
• Premature removal: Props or formwork removed before the permanent works have gained sufficient strength. This is often driven by programme pressure to reuse equipment on the next section.
• No TWC appointed: On smaller projects, the temporary works management role falls between contractors, and nobody takes ownership.

Prevention comes down to following the BS 5975 process without shortcuts. Appoint a competent TWC. Maintain the register. Do not erect without a checked design. Do not load without a permit. Do not dismantle without confirmation. These are simple steps, but they require discipline to maintain under programme pressure.

Tracking who holds TWC training, which permits are live, and when inspections are due can be managed through a centralised compliance system. AttendIQ tracks training certificates and competencies for every worker on site, including specialist qualifications like TWC training, so you always know who is qualified to fulfil the role.