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On paper, the RIBA Plan of Work is tidy and sequential: you finish technical design at Stage 4, then you build it at Stage 5. In reality, commercial pressure to start on site sooner means these stages increasingly overlap — construction begins on the parts that are ready while the design team is still detailing the rest. Overlapping Stage 4 and Stage 5 can genuinely save months. It can also cause chaos if it is not managed with real discipline. The difference is entirely in the control.
Why teams overlap the stages — and why it is risky
The attraction is obvious: on a design-and-build or fast-track project, waiting for every last detail before breaking ground can add months to the programme. Starting substructure while the superstructure is still being detailed compresses the timeline. The risk is equally obvious: you are now building against a design that is not finished, on a multidisciplinary project where the architect, structural engineer, and services designers are still resolving how their work fits together. Get the sequence wrong and you build something that has to be changed — abortive work, delay, and cost, exactly what the overlap was meant to avoid. If you are new to how the stages fit together, our guide to the RIBA stages is a useful primer.
The four disciplines that make it work
Running the stages in parallel is possible — it is done successfully all the time — but only when four things are managed tightly and deliberately:
- Sequenced design release. Design is issued to site in a controlled sequence that matches the construction programme — substructure information complete and coordinated before groundworks, and so on. The design programme and the construction programme become one linked plan, not two.
- Protecting the freeze where it matters. You cannot freeze the whole design, but you must freeze the parts being built. A design freeze applied element by element stops the team redesigning something that is already in the ground.
- Ruthless design coordination. With no slack in the programme, a clash discovered late is far more expensive. Multidisciplinary coordination has to be ahead of construction, not chasing it.
- Visible, owned risk. Every element being built ahead of completed design is a live risk that needs an owner and a mitigation on the register.
The information challenge
Overlapping stages multiply the cost of late information. When construction is waiting on a detail, a consultant running behind is no longer a programme irritation — it is a stopped site. Managing this is largely about managing the flow of information, which is why the techniques in handling late information from consultants become mission-critical. And because so much can go wrong at once, the overlap should be one of the most actively managed entries on your risk register.
The bottom line
Running Stage 4 and Stage 5 in parallel is one of the most demanding things a project manager can take on — and one of the most rewarding when it works. The saving is real, but it is earned through sequenced design release, element-by-element freezes, coordination that stays ahead of the build, and risk that is visible and owned. Manage those four things well and the overlap delivers the programme; neglect any one and it delivers chaos.
Running a fast-track project where design and construction overlap? JC Virtual PMs specialises in managing complex, multidisciplinary programmes where the stages run in parallel. Get in touch to keep yours under control.
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