29th September, 2021

A new iteration of the DfMA Overlay to the RIBA Plan of Work has been unveiled. Nigel Ostime, Partner at Hawkins\Brown explains what has changed and why it is so important to adopt its principles.

The DfMA (Design for Manufacture and Assembly) Overlay to the RIBA Plan of Work was first published five years ago. It corresponded to the 2013 Plan of Work (we now have the 2020 version) and, whilst providing essential thought-leadership, needed updating. Since the first edition the seven MMC categories have been established, Platform DfMA has become a reality and, under certain circumstances, government departments are mandating the use of offsite.

There has always been a degree of scepticism around offsite – haven’t we tried this before? – but its time has surely come. The construction industry moves slowly, weighed down by fragmentation, flat lining productivity and a lack of investment. So, whilst parts of the industry get it, others are dragging their heels. 

As sci-fi author William Gibson said: “The future is already here — it's just not very evenly distributed.” The overlay and accompanying report seek to help level up the industry.

The report sets out the current ‘state of the nation’ for offsite and provides links to the many publications that provide authoritative, in depth material on the subject. It sets out the drivers for change towards a manufacturing mindset, an exploration of market readiness, the critical process of optioneering – choosing the right solution, the impact of DfMA on traditional skills and roles, and an exploration of what the near future might look like. It concludes with a handy glossary – there is as much jargon in offsite as anywhere in the construction industry.

Getting it right at the start

In his preface Mark Farmer notes: “… the process of delivering a different outcome starts at the beginning with the client and their advisory team … How clients and their teams set their projects up from Strategic Definition stage onwards has massive impact on the success or otherwise of adopting manufacturing principles and then deploying effectively the various modern methods of construction (MMC) that are starting to really take hold in the UK construction industry.” The report explains that, to realise the outcomes our industry needs to achieve, DfMA must become established as the default approach, so that the systems and processes that underpin it are better understood by clients and become second nature to everyone involved. From the outset of the project the design team should follow a robust optioneering process. The report outlines a series of questions which should be answered at each RIBA work stage to frame the discussion. This is important as, for example, the technical design stage deliverables may need to be brought forward to as early as RIBA Stage 2.

MMC Adviser

The report introduces a new role of MMC Adviser who will initially facilitate the optioneering process to assess which construction method or system best suits the desired outcomes for the project. Their role is to challenge and provide support, as well as advising on the most appropriate supply chain for the project. This can be undertaken by the architect, if they have the necessary knowledge, or by a separate, specialist consultant. It could also be an inhouse function by the client if they have the capability. The MMC Adviser can be involved in all RIBA stages but their most important contribution is prior to appointing a manufacturer or contractor.

DfMA ≠ boring buildings

The consultees to the overlay were keen to dispel the myth that DfMA is a barrier to great architecture, provided the systems used are considered early enough. As the case studies in the report show, DfMA can produce award-winning architecture with buildings that are responsive to place and perform well functionally and environmentally.

Standardisation scares some architects who fear it will constrain their creativity and ability to respond to the site’s context. But a large part of the value that comes from DfMA derives from efficiency gains from making the same or similar components and assemblies repeatedly, especially if it uses a standardised process to achieve economies of scale. Much of this standardisation is hidden within the building (think bathroom pods or precast concrete for example) and an offsite building can be largely undiscernible from a traditionally built one. By avoiding reinventing the wheel, standardisation has the potential to speed up the design and assembly phases of projects and improve productivity, giving designers more time for the very necessary value-adding, iterative and creative processes.  

Pre-manufactured value

A proxy measure of the success of DfMA is the project’s pre-manufactured value (PMV), which expresses the amount of money spent offsite as a percentage of the total project budget. The higher the PMV, the smaller the proportion of the capital cost spent on prelims and on-site labour. A higher percentage is therefore an indicator of efficiency. Project teams need to start measuring and publishing PMV and the industry needs to use this data to assess where we are on the journey toward greater implementation of offsite.

MMC Procurement

Organised by MMC category and RIBA Work Stage, the BLUE sections on this matrix show, from earliest to latest, the recommended windows of opportunity for the appointment of members of the project team. The GREEN sections represent the typical duration of different parties’ appointment. The windows of opportunity vary depending on the category of MMC being considered. For example, it may be possible to decide on large-format cladding systems (Category 6) as late as RIBA Stage 4, but Category 1 solutions will need to be considered from RIBA Stage 2 to prevent costly re-design and programme delays.

The PINK dotted line running through Stage 3 represents the town planning application, which may/ in practice be submitted at any time during Stage 3. The YELLOW dotted line represents design freeze, which is essential for deriving optimum value from using offsite solutions. This is in each case shown as the latest time to fix the design and fixing it earlier is likely to bring greater the value.

The overlay and accompanying report can be downloaded free of charge from: and search ‘DfMA Overlay’. 

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