DfMA and BIM - Hot topics or misunderstood processes?

DfMA + BIM logo with cycle graphicDfMA and BIM: hot topics or still misunderstood processes that the UK Construction industry is at best struggling to adopt…. at worst, still sticking its collective head in the sand over?

Duncan Reed, Digital Construction Process Manager at Trimble Solutions (UK) Ltd discusses the question.

In an industry awash with reports, case studies and opinion pieces you would be unlikely to not know about BIM, the Government mandate and the benefits cited by many organisations from working collaboratively in a digital environment. But what about Design for Manufacture and Assembly (DfMA) and in particular, the RIBA DfMA overlay to its Digital Plan of Works (DPoW) – how well known is this report?

In conjunction with the Offsite Management School, RIBA published DfMA in September 2016. The documents set out to encourage architects (and the wider industry for that matter) to engage with offsite manufacturing and assembly. By providing this ‘DfMA Overlay’ to the DPoW, created by RIBA in 2013, the industry has been given a great document to show how digital processes and offsite manufacturing can and should be linked together. Whilst I believe that the structural market has effectively been doing DfMA and BIM for years, the question is has the rest of the industry woken up to the opportunities that these two processes, working together, can offer them?

Tekla Structures model looking through two windows in precast panel onto slab. Components in rendered wireframe showing rebar

DfMA can and does work. As I see it, the problem from the slow and poor uptake from the industry comes from the fact that many people don’t understand the full scope of DfMA – and crucially the implications of adopting DfMA are also the benefits. They are also very similar to the full implications of delivering BIM for a built asset, hence why they are intrinsically linked and so well aligned.

DfMA isn’t the same as offsite construction, or even offsite manufacturing. It takes the processes further: from construction to assembly. Assembly is an engineered manufacturing process that includes:

  • Correct first time products and components
  • Accurate manufacturing and assembly tolerances

Add Design to the Assembly process and it becomes patently clear why BIM and DfMA are such ideal partners. Design, an inherently virtual process, can be carried out digitally to ensure that the component, module, asset are defined and detailed in accordance with the customer requirements, tested for manufacture, coordinated for assembly and approved, virtually, by all the necessary stakeholders first. These are all basically BIM processes too such as virtual design, stakeholder engagement, agreed product data, clash management, construction rehearsals and the issue of appropriate operational data.

Point cloud visualization showing clash checking of existing precast panel against model

So adopting BIM first, gives individual parties and the wider team a perfect opportunity to roll out DfMA as one of the BIM processes on a scheme.

DfMA, like BIM, requires a cultural and behavioural change in the mind-sets of everyone; from the customer, through the design team, the supply chain and the operators and maintenance team responsible for an asset. If just one of these parties isn’t aligned, the project at best will not be as good as it could have been, or at worst will ensure the existing prejudices against DfMA and offsite are perpetuated.

It really is Modernise or Die – time to decide the industry’s future

Mark Farmer, Review of the UK Construction Labour Model

This is mirrored in my own experience of DfMA to date. Structural steel fabricators and precast concrete manufacturers definitely understand it, as do building services supply chains – they are the ones driving its adoption. Similarly modular offsite manufacturers also understand it – it’s their bread and butter too. However designers, customers, end users and possibly more importantly, principal contractors - the organisations often responsible for deciding to go down a DfMA route - can regularly be reluctant at best.

Nonetheless, the reason that DfMA isn’t always adopted is because it’s not considered at the right time. Looking at the RIBA DfMA overlay to their DPoW then it is at Stage 2 that a project should align itself to DfMA. Traditional contracting with ‘appoint late, buy even later’ mentalities by all parties is never going to work in this environment. This is where the behavioural and cultural changes are needed.

Two workmen supervise casting of panels in factory

Customer attitudes to built assets also need to change. They need to understand the value of built assets on the balance sheets and budget accordingly. It’s a well-banded statement but thinking Totex – total expenditure over the lifecycle of the asset not Capex – capital expenditure and Opex – operational expenditure as separate pots or silos, allows the value chain to be reinforced to deliver a better overall solution. Investing early – taking the benefits of digital design, virtual prototyping, construction rehearsals allows for a greater chance to develop a DfMA solution and derive the benefits this has to offer in improving quality and reducing risk for both the Capex and Opex phases – delivering a better Totex asset.

After many years working as a Design Manager and now working for a software vendor delivering structural steelwork and precast concrete solutions, it is obvious to me that parts of the construction industry have been doing DfMA as the business norm for years if not decades. The day the structural steel industry starting using bolts rather than rivets, it became a DfMA business but there was no real fanfare – it was just what the industry did. And this can be a fundamental part to the problem of understanding and adoption; DfMA, in a similar way to BIM, is not well understood or defined by the industry. Many design practices will tell you they are doing BIM, perhaps even they are delivering at Level 2 or beyond, yet after a few checks it can be apparent that they still don’t understand the fundamentals of document numbering and sharing and so are hardly able to deliver Level 1 in reality. And so it is the same with DfMA – businesses use this term as interchangeable with Offsite, but it is not.

Precast panel being maneuvered into place onsite, two workmen guide panel from beneath another in foreground holds tablet

In its crudest form a block is an offsite product, but laid by traditional means on site, so it is not DfMA. For it to be, then the block must be incorporated into a precast concrete panel, cast offsite in a factory environment to engineered tolerances and then erected on site, bolted into place to fit first time to those same tolerances to form the envelope of a structure. Something that is DfMA is definitely Offsite, but this does not necessary work the other way round.

Ultimately, and again aligned to the DPoW, the end of life of a DfMA ‘product’ should allow for dis-assembly, re-use or recycling, not just demolition insitu and down-cycling.

If the industry is to develop, to move forward and to even begin to start to consider ways to deliver on the Government Construction 2025 report, then it has to consider DfMA from the outset, combining this with the rigorous digital processes that BIM offers. As noted by Mark Farmer in his review of the UK Construction Labour Model, published just a month after the RIBA DfMA overlay – it really is Modernise or Die – time to decide the industry’s future. 

Onsite a team of workmen stand back in a row watching crane lift precast panel into position, prop's support panels

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