Temporary Works Design

Anything built to support the permanent works, or to give access to them, while they cannot do it themselves, and taken away afterwards: props and back-props, excavation support, formwork and falsework, scaffold, crane bases, working platforms, hoarding and facade retention. The Construction Regulations 2013 treat formwork, falsework and scaffold as structures, and count their design as part of the project's design process.

In practice the contractor who puts them up, usually through a temporary works designer the contractor appoints. The PSCS coordinates them on site, and the PSDP makes sure the temporary and permanent designs are compatible, but the HSA's guidance is clear that neither role replaces a competent temporary works engineer. Anyone whose decisions on site change a temporary works design can be a designer under the Regulations.

Yes. Regulation 2 includes the design of temporary works in the design process, so the temporary works designer carries a designer's duties under Regulation 15: to take account of the general principles of prevention, to give the PSDP or the PSCS in writing what the design depends on, and to cooperate with the other designers on the project.

Not by law. The coordinator is a role from BS 5975, which is a code of practice here rather than a regulation. Most main contractors appoint one anyway, because their own procedures and their insurers ask for it, and because it gives the design, the check and the permits one person on site who owns them. We work to whoever holds the role, or to the site manager where nobody does.

The certificate set out in the HSA's guidelines on the Construction Regulations, signed by the designer to confirm the temporary works design and what it relies on. It is recommended rather than mandatory, but it is what most PSCSs and main contractors ask for before anything is loaded, and it is what goes into the safety file.

It depends on how complex the design is and what happens if it is wrong. A supplier's standard solution used inside its limits is Category 0, and a simple design is Category 1. A design with more to it is Category 2, checked by an engineer independent of the designer, and anything unusual, innovative or with high consequences is Category 3, checked by a separate organisation. If you are not sure, send the brief and we will say which it is and why.

Yes, inside the limits it was drawn for. A standard design for props, trench boxes or a system scaffold assumes a load, a ground and an arrangement, and once a site moves outside any one of those it is no longer a standard solution. We check a supplier's design against the site it is going on, or design the part that falls outside it.

As many as it takes for the floors below to share the weight of the pour without any of them being overloaded at the age it is on the day. That depends on the slab thickness, the spans, the pour cycle and how quickly the concrete gains strength, so there is no fixed number: it is worked out for the frame and the programme, and the striking sequence goes on the drawing.

It is quoted against the brief rather than priced off a list. A single propping scheme or a crane base is a short design and a fixed fee; a basement sequence or a facade retention scheme takes longer, and an independent check is priced on its own. Put the date it is needed on site in the brief and the quote will say whether it can be met.