Getting it right with modern methods of construction

Successfully introducing new construction methods means considering interfaces, processes, and people, said Rennie Chadwick, global leader for transport and mobility at specialist consultancy Cohesive. Speaking at GIRI’s members’ meeting, he shared his personal experience of using modern methods of construction and what others can learn from the successes and mistakes of past projects.

In one example, Rennie discussed a project from the early 2000s that used factory-manufactured modules to beat programme pressures on a rehousing project. “We were working on a regeneration scheme and there was time pressure to unlock the part of the site where we had to rehouse 19 families. We discussed the challenge with an off-site manufacturing firm and designed a solution that was manufactured and fitted out in the factory. These modules were then transported to site, and we managed to construct a brand-new terrace from scratch in a week.”

The project won awards. The construction method reduced waste on site by 95%, the programme reduced by 75%, and there were no accidents. “It wasn’t even expensive. The solution came in at under £1,000 per sqm, which was around market rate for new-build social housing at the time.”

However, scaling up this success is where problems occurred. “We took the supplier on for another project that was 250 times the size. Initially, they made a whole range of bathroom pods, which worked perfectly, and some of the external cladding. Then enthusiasm ran away with us, and we gave them an order for a huge proportion of the cladding.”

This meant the company had to scale up their manufacturing capacity with new premises, which impacted cash flow, and the business folded.  “All our product was made, but it was in their yard. We rescued it and brought it to site – but not in the order in which it was intended to go on the building. The panels were designed to go in a particular sequence, and when they didn’t fit, we adjusted things a bit here and there… We hadn’t considered all the issues effectively and the result was a big problem.”

Lessons learned from this project cover three main points, said Rennie. The first is interfaces. “This project was a great lesson in the difference between making a complete building in a factory, with control over every aspect, to making part of a building, which then has to fit in exactly the right place otherwise the interfaces won’t work. It’s about tolerances and how we manage them, and having all the parameters properly expressed and understood.”

The second point is about processes. “Where you are fitting a system into a system of systems, you have to ensure your processes align with the controls. You need to pass the data from one party to the next as you go through design, manufacturing and assembly. There is a difference between doing something virtually and turning it into something physical.”

Finally, and most importantly, you need to think about people. “In this industry, most of our projects are delivered by multilayered organisational structures, and often you have self-employed agency labour doing the actual work. When you have various elements that you are bringing together and assembling, you must ensure that everyone understands the chain and what they are supposed to do. Most people don’t have a frame of reference for modern methods of construction. It’s not what they know how to do.”

It is also important to listen to all perspectives when embarking on a project of this type, said Rennie. “If we want people to accept the idea and champion it, we need to seek out the people saying it can’t work and understand their perspective so we can develop an approach to deal with it.”

Technology can help. “Not only can we now design things virtually, but we can also model the construction process and assemble a virtual version to test assumptions and issues. Being able to visualise things in near realistic level of detail is a great way of getting perspectives.”

Modern methods of construction, he concluded, bring change. And change brings risk. “How do we mitigate this? In the very broadest sense, we apply our engineering capability, but we also need to aim for balance. Listen to the naysayers as well as the enthusiastic adopters and take account of all those perspectives.”

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