Modular construction: Flat-pack to the future

Stuart Nathan looks at the increasing use of modular construction techniques and how this might represent a paradigm shift for this ancient form of engineering

Construction is one of the most fundamental engineering sectors of all. Ever since humanity emerged from caves, we’ve been building shelters. And the way that we’ve done it is remarkably unchanged. The building materials – whether wood and straw, mud, bricks, stone, or steel and glass – are transported to the site where the building will stand and assembled by specialised professionals into a custom-designed form.

modular construction
Panels are produced with all services and finishes incorporated and can be built like a scaled-up Ikea flat-pack

The next stage was established from the time we first had cities with a service infrastructure, so 4,000 to 5,000 years ago. Specialised tradespeople come onto the site and take over from the builders, connecting to services (in the case of plumbers and, more recently, electricians) and applying specialised finishes such as plastering and decoration. Times change, but a Roman builder or engineer would certainly recognise a building site in London today.

But that might be changing. The construction sector around the world, but particularly in Europe and most notably in the UK, is bedevilled by poor productivity and quality issues. One way to get around this, which is becoming increasingly important in a variety of construction sectors, is a shift to modular construction.

In past times, this was known as prefabrication and did not have a spotless reputation. There is a cachet to the surviving post-war “prefabs” in Britain, but at the time, although welcome, they were not universally liked – the need to build quickly and on constrained sites meant they tended to be small, unattractive and poorly finished. They were only meant to last 10 years and that any have survived at all is a testament to conservationists. Some readers might also recall the partial collapse of the Ronan Point tower block in East London in 1968, which was caused by poor assembly techniques being applied to prefabricated wall panels.

But today’s modular construction is different. It is marked by a desire to bring the advantages of modern industrialised manufacturing to the construction sector. Instead of building everything from small components on-site, whole rooms, fractions of complete buildings or highly finished panels are built in factories, with services incorporated into their structures, transported to site and assembled in place.

The ability to control the environment inside the factory, to use the most up-to-date digital design and manufacturing tools and to work under the strict quality control rules of the manufacturing industry, are key to the advantages of modular construction. Removing much of the work from open-air building sites – frequently wet and windy or too hot, often hazardous and always unpredictable environments – should make it quicker to construct a building, boosting productivity while also making it much safer and improving the final quality of the product.

modular construction
Modular construction allows the different types of rooms needed for a hospital, such as this Oswestry orthopaedic operating theatre, to be standardised

“Digital is key to this,” Peter Flint, chief executive of buildings and places at engineering infrastructure giant AECOM, told The Engineer. “It’s the ability for us to design in a 3D environment and the ability to send a design straight to manufacturing, that allows us do this properly. The key thing you want to do is create fabulous homes to a higher quality than currently, in a safe factory environment, and digital design is the tool that will enable us to do that.”

AECOM is active in the residential construction sector and favours a type of modular construction known as volumetric. Where much modular construction involves the manufacture of panels in a factory –whether these are wall, floor or ceiling – which are transported to the site as a flat pack and assembled accordingly, volumetric modular construction manufactures rooms – more like the portable classrooms that many of us who were educated in the 1980s will be familiar with – which are transported to site on the back of a trailer.

In AECOM’s case, these modules would be large: Flint explained that its prototype two-bedroom apartment is assembled from two modules. “You’re building a box, you’re fitting out, and you’re cladding it,” he said. “The boxes are built in the factory, finished. Then they are wrapped up, protected, lifted into place, and you need to do a little bit of work connecting up and joining them together: sit them on the slab in the right location, plug into services, and where the boxes join there is a little bit of site work required just to seal it up and finish the junction.” This level of off-site finishing allows as much of the building as possible to be made under high-quality, high-precision, controlled conditions, he explained. AECOM uses a lightweight, steel-framed structure to keep the weight of the finished modules low enough for them to be lifted and transported easily; weight having previously been a stumbling-block for the volumetric approach.

The innate drawback with the approach is that it depends on a very high level of standardisation between units. Variation is kept to a minimum, and this means that every unit is more or less identical. “It won’t work in every case – you wouldn’t use it for the Tate Modern extension, but I don’t think the repetition necessarily means bad architecture,” Flint said. Indeed, from the start of its ventures into modular residential construction, AECOM’s design partner has been the Rogers Stirk Harbour Partnership, the architecture practice of Richard Rogers, probably the world’s most famous and revered architect. “They’ll be beautiful spaces,” Flint commented.

London might be getting a taste of the Rogers-designed modular housing sooner rather than later. Until recently, AECOM was heavily involved in a project to redevelop the Silvertown area of Docklands, with 3,000 homes on 62 acres. The project was a partnership with developer First Base, with whom AECOM has a long relationship, but the site was sold and the product is now on hold. Flint hopes to be involved with whomever the new owner of the site turns out to be. A particular selling point might be that the company planned to build the factory to manufacture the modules on the site, thereby providing employment for this relatively deprived region of London.

“The local authority was very interested because it provides not only fast, precision-built housing but also an opportunity for local employment,” Flint said. “And that’s a case for a lot of London boroughs, the housing requirement is quite clearly defined and if the solution is also providing local employment the local authorities get very excited.”

AECOM is producing full-scale prototypes of its modular housing product in Newark, Nottinghamshire, where it will be fully tested, and is in discussions with several developers over putting its plans into practice. It is also partnering with the Advanced Manufacturing Research Centre (AMRC) in Sheffield on the engineering aspects of setting up manufacturing for its product.

With software such an important part of the modular construction paradigm, it’s hardly surprising that software houses are a major part of the story. Sarah Hodges, Autodesk’s senior director for construction business strategy, explained that the company’s role was almost as a nursemaid to guide companies in the construction sector into the world of manufacturing, which up to now has not been part of their make-up. Although they have bought items from manufacturers, such as fixtures and fittings, they have not been manufacturers themselves.

Autodesk is, of course, also not a manufacturer but, as The Engineer has reported, its business is now focused around helping its customers produce digital designs and working out how to give those designs physical form. “What we think about here is industrialised construction,” Hodges said. “We think of that as having three main components. The first is design for manufacture. The second component is what happens in the factory in terms of prefabrication and modular construction, and the third is what happens on the construction site itself. So we seamlessly design directly for manufacture, we manufacture the component in the factory, and then we install it on site.

While AECOM is a client of Autodesk’s, the software company is seeing a great deal of modular construction activity in a non-residential sector: namely, healthcare. For hospitals, the standardisation that is so key to modular construction is a positive advantage. “Bathrooms, for example, tend to be the same wherever they are in a hospital,” Hodges explained. “They have the same dimensions, and the same fittings with the same layout. So they can be produced in bulk not only for each individual site, but for multiple sites.”

For projects in healthcare, which according to Hodges was the biggest market for modular construction two years ago (residential was catching up fast and may now have overtaken it), five different standardised types of room can be specified for a hospital and designed in detail to be produced in factories and assembled on site. “We can specify in detail the components needed for those five types of room, fabricating them and delivering them just in time on site for assembly.”

There are two main driving factors for the prevalence of modular in healthcare, Hodges explained. The first is that there are many ageing healthcare facilities in need of modernisation, and the second is the ageing population of “baby boomers” who are increasingly in need of hospital facilities. “Hospitals tend to look the same wherever they are anyway, and modularisation and standardisation are an advantage when you are looking after people in different places who have similar conditions and need similar sets of treatment.”

While construction may, until now, not have had an image as a high-tech industry, the tools are now being applied to it are right at the cutting edge – up to and including artificial intelligence. “Today, we are spending a lot of time and research and development into how we more seamlessly design to the right level of detail and specification to directly manufacture, and this is taking on aspects of machine-learning intelligence to identify patterns that will help in architecture and get that model ready for fabrication,” Hodges said.

Because Autodesk works with a variety of clients who embrace different concepts of modular construction technologies, it is not tied to the volumetric model that AECOM uses. Among its partners in the modular construction field are Boston-based Manufacton and San Francisco’s Project Frog (Flexible Response to Ongoing Growth), both specialising in the manufacturability of modular designs and the latter being a specialist in panelisation to produce flat-packed designs for maximum transportability to site. “They think about prefabrication and flat-packing for just-in-time delivery and optimisation on site, so the components are very easily assembled, almost like pieces of IKEA furniture but on a much larger scale,” Hodges said.

Architects are already converts to digital methods and often use a system known as BIM (building information management) to incorporate many details of the materials and products used in their designs into the working drawings. “We did a bit of research around using BIM-based systems to drive modular construction and these models estimate a 90 per cent reduction in overall waste on the project through the level of detail in design and driving straight to fabrication: they’re stating a 30 per cent increase in productivity and reducing safety risks by a factor of four,” Hodges said. “That’s a tremendous impact on many of the factors that are critically important to the construction industry, primarily around the massive amount of waste that is produced in construction and keeping an eye to making sure we are keeping all our workers safe.”

Hodges’s role includes a great deal of international travel and she believes that the UK, the Netherlands and the Nordic countries are well ahead of the rest of the world in adopting modular construction approaches. Part of this is a huge demand for housing and infrastructure; in the UK’s case, to update the ageing housing stock and the built environment, and elsewhere to add capacity in smaller cities. But for this region, she believes, the unpredictable weather and bad conditions on building sites are a definite contributing factor.

Another new development, Hodges suggested, may be the establishment of “flying factories” to manufacture the modules. Part of the reason for this is logistical factors in transporting modules to site are greatly reduced if the manufacturing is close by as possible. It may also reduce costs to be able to put up a temporary factory rather than relying on a permanent large facility, she said, adding that companies such as Skanska were looking into this possibility.

“Paradigm shift” is an overused term in the engineering world: everybody thinks that they are in the midst of a revolution even when they are not. But in the case of the construction industry, Hodges believes that modular techniques really might represent this much-maligned term, seeing a shift for this industry from its mud-clogged, risky millennia past to a future joining the automotive, aerospace and other manufacturing industries as a factory-based, well-lit, climate-controlled modern industry with little relation to what those Roman builders might have recognised. Some veterans will doubtless mourn the passing of scuttling around scaffolding beams and hoisting bricks around, but it’s a changing world and many would be glad to see the back of it. n