Why do RIBA Stage 4 and 5 overlap?

RIBA Stage 4 is defined as ‘Technical Design’. Stage 5 is ‘Manufacturing and Construction’.

Very rarely does the former stop before the latter starts.  

Technical Design does not stop before Manufacturing and Construction start.

The very word ‘stage’ suggests a process whereby one period will conclude before the next one is started.  And herein lies the confusion: everyone likes a clear line in the sand for signoffs and payment.  


But with the move away from traditional (full design) procurement towards D&B and fast-track management type contracts, technical design may continue right up until the project’s completion.


Conversely, early contractor involvement can even lead to the ordering of off-site prefabricated elements well in advance of taking site possession or enabling works.  


And if the recently reported post-COVID period of material shortages continue, we should expect a greater use of early procurement to secure construction supply chains.    

For the design process, this means the need for even greater clarity around what is required when, by whom, and at what level of resolution.

 At Plan A Consultants we produce our own bespoke Design Responsibility Matrix (DRM) to ensure that future contractors understand what elements of the design need completing with specialist input, and then approval for installation via a process of technical submittals and shop drawings.  A detailed Stage Design Programme is also produced for our clients, setting out the release of Stage 4 information and ensuring tender periods are clearly defined.  

Both these documents (DRM and Programme) should of course reflect the entire design team’s Appointment and Scope of Services, making it clear who is appointed for the Construction period and its inevitable flood of queries and clarifications around the design as it is concluded by others.  


Scope creep into Stage 5 is a real risk for those designers without a novated or Client Quality Monitoring role.  Early contractor involvement, whilst bringing many benefits in terms of buildability advice, can result in a fundamental rethinking of design strategies – something that needs tracking against decisions already agreed during the earlier stages and change management is essential to compensate any abortive work during this overlapping of Stages.