Last edited 19 Feb 2021

Technical design stage for building projects

The process for completing the design and construction of a building is often divided into notional ‘stages’. This can be helpful in establishing milestones for the submission of progress reports, the preparation of information for approval, client gateways, and for making payments.

However, there is a great deal of ambiguity between the naming of stages and the definition of what individual stages include and so it is important that appointment documents make it clear precisely what activities fall within which stage, and what level of detail is required.

Generally the phrase ‘technical design’ refers to project activities that take place after the detailed design (or 'developed design' or 'definition') has been completed, but before the construction contract is tendered or construction begins.

Increasingly, however, technical design may continue through the preparation of production information and tender documentation and even during construction itself, particularly where aspects of the technical design are undertaken by specialist subcontractors.

The lead designer co-ordinates the preparation of the technical design. As this may involve design not only by the client’s core design team but also by specialist subcontractors, it may be appropriate to organise a specialist contractors' start-up meeting at the beginning of the stage. A design responsibility matrix can help allocate design tasks between the project team members, and on complex projects, it may be necessary to appoint a design co-ordinator responsible for co-ordination and integration of different aspects of the technical design.

There is some skill in establishing the order for undertaking technical design. For instance the ceiling tile grid has to be established so that light fittings, sprinkler heads and smoke detectors can be located centre of tiles and access provisions to services in ceiling voids can be established. Similarly, mullion positions for cladding systems dictate partition locations between cellular offices. Drainage set to falls has priority over ceiling pipe work, ductwork and electrical trunking the latter being more flexible in its routing. It is argued by some that co-ordination between the different aspects of this technical design is best carried out by the client’s design team despite the increasing tendency to transfer responsibility to contractors.

By the end of the stage the architectural, structural and mechanical services design and specifications should describe all the main components of the building and how they fit together, any performance specified work should be defined and there should be sufficient information for applications for statutory approval to be completed. Room data sheets are also likely to have been prepared along with outline technical specifications.

Regular reviews should be carried out during the stage to assess construction sequencing, buildability, the interfaces between different elements of the design, the project programme and risk. The client’s design team may be required to review design information prepared by specialists to ensure proper integration into the wider design.

It may be appropriate to arrange visits to the specialist contractors' premises to assess samples or mock-ups and to witness tests. Some samples may require approval by the client.

Once the client is satisfied with the technical design, the lead consultant should freeze the design and specifications and introduce change control procedures and remaining statutory approvals and other approvals should be completed.

The RIBA Plan of Work 2020 suggests that technical design (stage 4): '...involves the preparation of all information required to manufacture and construct a building. The core documents at the start of Stage 4 are the Responsibility Matrix, the Information Requirements and the Stage 4 Design Programme, which is heavily influenced by the Procurement Strategy.'

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