Watch our AT Schüco webinar exploring modern methods of construction and how we decide which ones are best suited to our building projects.

It should not be surprising that the term ‘modern methods of construction’ encompasses a wide range of approaches. After all, there are many types of traditional construction methods so why not modern ones? The first speaker at this webinar, Tom Lewith, co-founder of TDO Architecture, reminded the audience that the government has defined seven different types of MMC.

He then went on to describe his practice’s use of method 1, which is volumetric, modular and fully factory built. This is what the practice used on the terrace of 10 FAB Houses that it designed for Places for People with Urban Splash to build in North Shields.

Speakers from left to right: Tom Lewith, Sasha Bhavan, Jonathan Green, and Eva MacNamara

Lewith talked about the advantages and disadvantages of the volumetric approach. It was not surprising that the advantages included a reduction in waste, better access to labour, higher quality and improved airtightness. But in addition, he said, there was ‘a lot of design opportunity’. This came from looking at how the process could enhance the design. ‘We spent a long time understanding the systems and factory and learning from previous developers,’ he said.

TDO’s Fab House in North Shields is a new modular constructed dwelling typology designed for joint venture developers Places for People and Urban Splash (ph: Peter Cook)

It was possible to expose the ceiling joists because of the extra strength that came from having two cassettes on top of each other. Acoustic separation was in the floor above. The precision engineering resulted, he said, in ‘beautiful alignment and details’. The architect exposed the timber on the staircases and made junctions in such a way that there were never four corners meeting.

The challenges, Lewith said, lay largely with the procurement process, A shortage of potential providers makes it difficult to get competitive tenders. And the need for economies of scale means that few projects are large enough. He also acknowledged that having transport constraints dictate dimensions meant that a temporary situation determined the form of the final fabric. For these reasons, although delighted with the result of FAB, the practice is now looking at panellised systems.

Interior view of Fab House (ph: Peter Cook)

Knox Bhavan Architects takes a far more bespoke approach to offsite manufacture, and certainly is not worried about competitive tenders. Instead, it has built a relationship over several projects with a specialist manufacturer, BlokBuild. This has evolved from making ceiling elements for the practice’s own office into working on a number of houses.

The collaboration, also involving engineer Price & Myers, has led to an evolution in ways of working where each party has learnt lessons and improved on the next project. For instance, on March House, the first residential project that the team did together, BlokBuild made custom-designed cassettes for the floors, walls and roof.

Designed by Knox Bhavan, in collaboration with offsite construction specialist BlokBuild, March House is a prefabricated, timber-frame, stilt house located on the banks of the River Thames (ph: Edmund Sumner)

The contractor refined the size of the cassettes through the process and satisfied a wide range of requirements. The house was quick to build, and units came in easily through the restricted access. There was little wastage of materials and the cassettes framed generous openings. The one disadvantage came from protruding nail plates, which made the fixing of cladding difficult. On the next project, currently under construction, BlokBuild has recessed the nail plates.

Scatterdells Lane by Knox Bhavan, in association with BlokBuild, is a prefabricated timber-clad house in Hertfordshire that been specifically designed to cater for the needs of its inspiring paralysed owner

Having extended from an interior to whole houses, the ambition has increased again. Knox Bhavan and BlokBuild are working on a project to provide homes on back land sites for a community land trust in Bristol. They are working together to produce a kit of parts that could apply to anything from a single dwelling in a back garden to a medium-size development. BlokBuild intends to manufacture locally, helping to provide jobs.

3D digital fabrication model of the BlokBuild construction system with overhang detail at Scatterdells Lane, and real-world detail fabricated and assembled on site.

This approach is based on sophisticated digital technology but also depends on an almost old-fashioned working relationship. Sasha Bhavan, senior partner of Knox Bhavan, said, ‘This works because we get on really well together. When you are trying to get a new way of thinking you need that, not a combative contractor process.’

There was little combat in the last project shown, but also nothing that was old fashioned. Eva MacNamara, associate director of Expedition Engineering, discussed the AVA system of bridges being developed for Network Rail.

AVA Modular Footbridge, designed by Hawkins\Brown with Expedition Engineering (cgi: Hawkins\Brown)

Being designed by a collaborative team, this is a system of manufactured bridges that should be faster and cheaper to install and give an improved user experience. MacNamara said that for a typical traditional footbridge, the material cost is less than 17 per cent of the total, and that site time is typically 9-12 months. There are obviously gains to be made.

In addition, MacNamara said, ‘Network Rail is looking at access for all, safe places to wait, and an inviting journey across the bridge.’ The team has come up with a design that is, MacNamara stressed, manufactured not fabricated. A lot of the effort has gone into the design of passenger lifts that are, she said, ‘plug and play’ rather than needing the time-consuming erection process that previously slowed projects down.

The modular bridge is designed to reduce construction, delivery, and management costs (cgi: Hawkins\Brown)

The team is building a prototype at a test facility at Widmerpool where there are live trains but no public and, says MacNamara, has learnt a lot. Made of folded stainless steel, the bridges should have a long life and are designed with circularly economy principles, meaning they have a lower whole life carbon than Network Rail’s existing footbridges. Next up is work with the Manufacturing Technology Centre to produce a configurator that should help Network Rail select the right bridge for any position and automate a lot of design work. This will, said MacNamara, move the project on from the third (digital) industrial revolution to the level of the fourth, where everything becomes interconnected.

This is evidently within the scope of modern methods of construction – as are the other two examples. Which approach will dominate? There is probably a place for them all. The future, like the past, is unlikely to have a one-size-fits-all solution.