It is rare these days in our industry for a day to pass without coming across the acronyms DfMA (Design for Manufacture and Assembly), MMC (Modern Methods of Construction), OSM (Off site Manufacture) or any other number of buzz phrases relating to the benefits of factory production and assembly replacing on site construction.
It represents a paradigm shift in the way projects are undertaken, from the Clients initial definition, through design and procurement, and into the assembly itself. We are all understandably excited about this and its potential to transform our industry, but why does it still make up such a small part of our construction output?
In this article we give a quick definition of the types of DfMA, briefly review the drivers for change, and then focus on the remaining barriers in an attempt to understand what is holding up the off-site revolution.
The different levels of offsite construction were broadly defined over a decade ago, and still apply now;
Component – individual elements to be constructed together on site
Sub-assembly – elements are combined, typically only within one discipline
Planar – two dimensional products which can be quickly assembled together on site – may span multiple disciplines
Volumetric – a three-dimensional product featuring input from multiple disciplines
Modular – a volumetric solution which is fully completed in the factory and needs only to be assembled with other units.
There are also hybrid approaches where more than one of the above approaches are combined within a project.
Further to all of the above, P-DfMA is a key aspect of a government proposal published in 2018 whereby the adoption of Modern Methods of Construction could be driven by adoption of a platform approach to DfMA. In other words, an open source library of standardised components which would allow highly efficient manufacturing at scale.
In 2016 the Farmer report gave a fairly damning assessment of the construction industry and focused the mind with the phrase ‘Modernise or die’. The diagnosis suggested that the industry has a ‘survivalist’ nature, non-aligned interests between parties, and that strategic intervention needs to be led by government to effect transformational change.
When the report is considered along with climate change, our housing shortage, low levels of manufacturing and skills shortages in the industry, it is clear to see that we cannot continue as we have been doing indefinitely.
DfMA has the potential to transform some of these concerns into opportunities;
Offsite manufacture and assembly on site needs a skilled labour force, but requires considerably less labour than a traditional construction project. Smaller numbers and more controlled environments have obvious benefits for safety and well being of workers.
Build time can be significantly reduced, and quality correspondingly increased, which could allow a rapid housebuilding programme to be implemented. The increase in PRS housing and its demand for a higher quality product would seem to have an obvious synergy with DfMA.
Material wastage is significantly reduced, and there are obvious benefits to the reduction in site traffic with fewer deliveries. The approach to design for DfMA should allow full lifecycle costing to be undertaken much earlier in the procurement process.
Manufacturing levels would be invigorated by large scale DfMA adoption, which could also boost the industries exporting capability.
In addition to the above points, the key technology to facilitate DfMA is BIM, which is now close to being universally accepted as the essential norm, albeit still with some way to go in terms of achieving full level 2 and beyond.
There is no doubt that there are some impressive projects being delivered with DfMA approaches, and major contractors and housebuilders are making huge investments in developing their own systems and factories. Indicators are that adoption is unlikely to spread beyond the projects that these companies are directly involved with, and the fact that less than ten percent of projects are being procured in this fashion is unlikely to change in the near future.
So given the above, what are the barriers that remain to a more widespread adoption of DfMA across the industry?
It goes without saying that pipeline is a key contributor toward stakeholders moving toward DfMA. The government has via its 2018 Construction Sector Deal proposals committed to significant investment in transforming construction and supporting the commercialisation of new construction technologies and techniques.
One of the key issues is intellectual property – as discussed above there are many systems being developed in isolation, but for the true benefits to be realised there needs to be a universal approach, or at least a high degree of crossover between systems. Only then can the P-DfMA approach and its efficiencies of scale be realised. This is a difficult barrier to overcome – is it realistic that companies who have already invested huge sums in their own systems will share all that they have created and learned, and if so, who will lead the process of standardisation?
Another obvious issue is industry inertia against change. For main contractors the coordination of trades and construction on site is their raison d’etre, a large proportion of this would be undertaken in the factory environment. For some specialist subcontractors their way of working may disappear almost entirely.
There is currently no proven procurement model for DfMA, one of several points made by the RIBA in response to the governments proposed P-DfMA approach. The government also needs to lead the way in adopting best value rather than best price, as currently a factory approach can be up to twelve percent more expensive. It is clear that a DfMA project needs to be steered as such from the earliest of stages of design – trying to switch to DfMA at RIBA Stage 3 or 4 is unlikely to reap the benefits, and will need to take several steps backward before it could start to move forward. The RIBA has published a version of its plan of work tailored to DfMA which is very helpful in understanding the way in which the off-site approach needs to influence design.
Finally, there remains a question of long-term adaptability. It is argued that by their very nature modular systems are easily dismantled and re-configured, but it is hard to imagine how substantial refurbs which change the usage and feel of a building after trends or fashions dictate could be applied to such an efficient and specific original design. This is perhaps not so much a barrier for now, as a future unknown – there is at least the opportunity to look to other countries which are further along the modular timeline to gain some insight into this.
There are positive discussions and debates about all the above issues, and in time the industry will work through them all one way or another. Here at London Structures Lab, we are trying to focus on what we can do not just to drive these issues forward, but also to best facilitate DfMA within the current constraints outlined above.
Our view is that with the kind of complex sites and briefs that we are used to dealing with, there will always be an element of bespoke or dare we say traditional construction required, particularly where there are basements above or in the vicinity of existing assets. This will also be the case with refurbishment projects, which do not preclude DfMA but are likely to have bespoke interfaces for every project.
If Clients are willing to engage forward thinking engineers and architects from the very outset of such projects, this should allow areas which may be suitable for DfMA to be identified, and design for both types of construction can be progressed together in an integrated process. Ideally this would avoid being tied to any particular off-site system, striving toward the open source approach discussed above. By doing this from the beginning of the project this will enable procurement to be undertaken in a more appropriate way, and avoiding profit and prelims being applied to the full project when a clearly identified proportion of the project is designed to be manufactured and potentially completed off site.