Why do RIBA Stages 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.  

Although the RIBA plan sets out discrete stages, in most projects stages four and five have at least some overlap.

The very word ‘stage’ suggests that one period will end before the next one is started.


Everyone likes a clear line in the sand for signoffs and payment. RIBA describes stage 4 as completing all the design information needed to construct the project, and stage 5 as manufacturing, construction and commissioning.


By the end of stage 4, the project will have agreed manufacturing, construction information, final specifications and submitted the building regulations application. In stage 5, the only design work is responding to site queries. 


However, in the real world, manufacturing and construction (stage 5) often begins before the technical design (stage 4) is complete.

As the industry moves away from traditional (full design) procurement towards design-and-build and fast-track management-type contracts, technical design may continue right up until the project’s completion. Early contractor involvement can lead to their ordering off-site prefabricated elements, well in advance of taking site possession or enabling works.


What’s more, if the post-COVID period of material shortages continues, we can expect more 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.


Scope creep into Stage 5 is a real risk for those designers without a substitute contract or client quality monitoring role. 


While early contractor involvement can bring many benefits in terms of buildability advice, it can also lead to a major design strategy rethink. That will need careful tracking against decisions that were made during the earlier stages, and change management will be needed to manage any work that needs to be redone during this overlapping of stages. 

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 using a process of technical submittals and shop drawings.  Our design managers also produce a detailed stage design programme, which sets out the release of Stage 4 information, and ensures tender periods are clearly defined.  

Both these documents (DRM and programme) reflect the entire design team’s appointment and scope of services. They will be 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.  

by Associate Design Manager Simon England


​Contact us at Plan A to find out more about how our design responsibility matrix, stage design programme services and change management services can help ensure that overlapping stage 4 and 5 works to the best advantage of your project.