--- title: "Temporary Works Design" description: "Propping, excavation support, formwork and crane bases designed for contractors, independently checked and certified on the RF2." updated: "2026-10-12" url: "https://www.petruf.ie/services/structural-engineering/temporary-works-design" --- # Temporary Works Design > Propping, excavation support, formwork and crane bases designed for contractors, independently checked and certified on the RF2. Temporary works hold up the permanent works before they can hold up themselves, so they are designed against them: what the slab below can carry on the day it is loaded, where the frame is stable and where it is not yet, and what changes when the sequence does. Under the Construction Regulations 2013 a temporary works designer is a designer, with the same duty to tell the PSDP and the PSCS in writing what the design depends on. We take that appointment from main contractors, specialist subcontractors and equipment suppliers across Ireland, as chartered engineers with professional indemnity behind the signature. The same office designs permanent frames, precast included, so the props, the pour sequence and the erection stability are checked against the structure they are holding up rather than against an assumed one. ## What we design ### Propping and back-propping Props under new slabs and through the floors below them, sized against the strength the concrete has on the day it is loaded, with the striking sequence set out. ### Openings in existing walls Needles, props and temporary beams for a wall being opened up, designed together with the permanent beam that takes over from them. ### Excavation support Trench and basement shoring, sheet piles and underpinning sequences, designed from the ground information rather than from a guess at it. ### Formwork and falsework Wall and column shutters checked for concrete pressure and rate of rise, and falsework designed to I.S. EN 12812. ### Crane bases and outrigger pads Tower crane foundations and the pads under mobile crane outriggers, checked against the bearing the ground or the slab can actually give. ### Working platforms and piling mats Granular platforms for piling rigs and cranes, designed for the track loads the plant on site applies. ### Facade retention Steelwork that holds a retained front up while the building behind it comes down and goes back up, staged with the demolition. ### Hoarding and scaffold Hoarding designed for wind, on kentledge or foundations, and scaffold designed wherever the arrangement falls outside the standard solutions. ### Temporary bridges and access Gantries, access structures and temporary crossings that carry plant and people over a gap the permanent works have not closed yet. ### Precast erection stability The propping and the lift sequence that keep a precast frame stable until its connections are made and its floors act together. ## Design check categories BS 5975-1:2024 sets how independent the check of a temporary works design must be by how complex the design is. In Ireland it is a code of practice rather than law, and it is what most main contractors' procedures ask for. ### Category 0: Standard solutions A published or proprietary solution used inside its stated limits. Checked by another member of the site or design team. ### Category 1: Simple designs A straightforward design with little that can go wrong. Checked by another member of the same design team. ### Category 2: More complex designs Checked by an engineer who was not involved in the design and was not consulted by the designer. **We check and sign.** ### Category 3: Complex or innovative designs Unusual methods, high consequences or designs at the edge of the guidance. Checked by a separate organisation. **We check and sign.** ## What you receive Every design is issued as a set the site can build from and the safety file can keep. - Calculations and drawings, issued for construction - The loading limits on the permanent works at each stage - The erection, loading and striking sequence, on the drawing - The criteria for the permit to load and the permit to strike - An independent check at Category 2 or 3, where the job needs one - The RF2 certificate, and the information the PSDP and the PSCS need from a designer ## From our projects ### [60 Dawson Street](https://www.petruf.ie/projects/commercial/kells-project) Precast panels lifted under live overhead lines, each on its own delivery slot and lift sequence, with temporary propping holding the frame until the connections were made. ### [73 North Wall Quay](https://www.petruf.ie/projects/commercial/73-north-wall-quay) Propping held the precast frame through erection until the connections were made and the slabs could act as a diaphragm. ### [The Hotel at Goffs](https://www.petruf.ie/projects/hospitality/club-hotel-goffs) Temporary propping held the frame through erection, braced against wind until the connections were made. ## The questions that come first ### What counts as temporary works? 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. ### Who is responsible for temporary works in Ireland? 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. ### Is a temporary works designer a designer under the Construction 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. ### Do I need a temporary works coordinator in Ireland? 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. ### What is an RF2 Temporary Works Design Certificate? 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. ### Which design check category does my job need? 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. ### Can we use a supplier's standard design? 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. ### How many floors of back-propping does a new slab need? 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. ### What does temporary works design cost, and how long does it take? 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.