Labour shortages and supply chain difficulties are prompting increased use of MMC among housebuilders, but that route needs refining
The government’s housebuilding target of 300,000 homes a year has been inextricably linked to its support for modern methods of construction (MMC). It mandated MMC’s greater use through its funding programmes to give the scale and pipeline needed to increase factory production’s attractiveness – particularly for category 1 (volumetric) and 2 (panelised) systems – and potentially deliver more homes faster.
But housebuilding totals remain far short of 300,000; manufacturers have fallen by the wayside and schemes stalled. An investigation by the House of Lords built environment committee concluded in a letter to the communities secretary in January that government had ‘too easily accepted that undirected and non-strategic investment of public money was the obvious way of providing this assistance’.
Still, the committee recognised the role of MMC, ‘especially in the context of an ageing skilled workforce and the inefficiency of traditional housebuilding methods’, and it has made strides in markets such as modular in the build-to-rent and student accommodation sectors. So where does MMC go from here?
High or low tech
‘We think making modular work in the planning and construction environment in this country is extraordinarily difficult,’ says Andrew Matthews, director of Proctor & Matthews, which has worked on government-supported projects deploying MMC at scale. ‘There is this obsession with the idea that modular can deliver things fast and with the numbers, but it’s a myopic view without considering all the other factors, like planning, site complexity and different markets.’
Given these other influences, fellow director Stephen Proctor sees greater potential in the use of panelised systems, like timber structural insulated panels (SIPs). ‘In terms of sustainability and creating an energy-efficient envelope, SIPs is a really good route to deliver that,’ he says. ‘That’s probably where the future lies in MMC for low-rise family housing.’
With Irish housebuilder Glenveagh Homes, the practice recently undertook research into creating lower-rise MMC housing typologies, particularly to better reflect the aspirations of 18-30 year olds, revealed by focus groups. The research considered manufacturing, design and construction processes, interrogating how homes could be delivered in modular and panelised systems, using light gauge steel and timber.
As a result Glenveagh is introducing advanced robotics for panel production at its timber frame factories rather than adopt modular. House types are designed for traditional construction and for timber and light gauge steel, insulated concrete formwork (ICF) and timber frame. This focus on multiple construction options, rather than a rationalised approach, reflects a need for business resilience amid today’s labour shortages and disrupted supply chains.
In the wake of Covid and with the start of the Ukraine conflict, Glenveagh overcame materials and skills challenges by adopting a locally manufactured ICF system for its 69-home Wilkinsons Brook scheme, on the edge of Dublin. Designed by Proctor & Matthews with contributions from de Blacam & Meagher and construction stage detail design by Doran Cray, the scheme’s small scale, variety and distinctive features would have ruled out modular. It has diverse house types, a clustered arrangement around neighbourhood spaces and in-curtilage parking that conceals cars from view.
ICF walls are faced externally in render and brick slips, the latter installed by readily available tilers rather than scarce bricklayers. Although the embodied carbon in ICF can be significant, its high levels of insulation combine with rooftop photovoltaic panels and air source heat pumps to give the homes an A1 building energy rating. MMC is essential to address skills shortages and also to meet increasingly stringent thermal performance requirements in housing, as traditional construction ‘just demands too much of the tradespeople on site’ says Matthews.
Projects like this offer a counterpoint to the UK government’s backing for production and deployment on a massive – and often modular – scale and speak of varied approaches to MMC. The practice’s homes at Greenwich Millennium Village in east London, created in the early noughties, were built using what it then called component driven assembly. ‘We couldn’t do modular because it didn’t really exist to deliver that kind of sophistication,’ recalls Matthews. ‘But there was something very sensible about it because everything could be made in an on-site factory, which was sometimes quite low-tech.’
The firm has identified potential to source all non-engineered structural timber needed for the scheme in Sussex
Growing manufacturing
Sussex developer Human Nature plans to use timber MMC for its first scheme, the Phoenix in Lewes, and wants to draw on the county’s natural resources to do it. It expects the move to be good not only for residents, nature and the environment, but also for business and local people. ‘If we can create a market in construction for Sussex timber, that will help owners to invest more in their woodland, employ more people and increase the supply chain and jobs for young people,’ says Human Nature founder and CEO Jonathan Smales. ‘We’ve been pleasantly surprised that timber is available at a cost that is affordable’.
The thinking is part of the developer’s regenerative ‘whole place’ ethos, which has seen it evaluate potential social and environmental impacts of mobility infrastructure, energy, buildings and behaviour change on the Phoenix site and beyond. When it comes to the embodied carbon of the upcoming neighbourhood of 685 homes, which won planning consent in February, Smales speaks bluntly of the challenge. ‘In a way, development is like big oil,’ he says. ‘We meet our housebuilding targets in this country in a conventional way and we’re adding a massive burden to the climate problem.’
Materials from former industrial structures on the site are being re-used to create the scheme’s community buildings. But homes had to be newbuild, so Human Nature began a dialogue with timber specialists Stora Enso, Eurban, TDO and Greencore and structural and civil engineer Whitby Wood. Two days of workshops followed, bringing together 30 representatives from design, construction, the supply chain, insurance and other areas to discuss everything from legal issues to the use of local timber. ‘On the afternoon of the second day, we [asked] everyone whether it was credible and appropriate for us to commit in the way we have,’ says Smales. ‘The consensus was we could build up to 18m, which is what we wanted to do anyway.’
The developer has taken a similarly collaborative approach to refining its proposal ahead of the start of construction next year. Its in-house design team worked with Periscope and Arup on the masterplan and 10 more architects are designing buildings for specific land parcels.
Smales describes the company’s way of working with its project team as ‘build and design’, which, he explains, ‘is our way of avoiding value engineering at the end’. Team members are also equipped with the scheme’s playbook, a guide to materials use, including local timber, design and construction created by the project’s executive engineer Whitby Wood. This continues the build-and-design approach but aims not to be over-prescriptive. ‘It sets out an approach and a process,’ says Whitby Wood director Kelly Harrison.
The firm has identified potential to source all non-engineered structural timber needed for the scheme in Sussex, ‘if you had enough time, because you have to do it in a sustainably managed way,’ points out Harrison.
Design of the 44 homes in the site’s first land parcel has provided an opportunity to test the playbook, balancing embodied carbon, design efficiency and consumer aspirations for open-plan, varied living spaces. ‘You can have a playbook, but it needs to have that 20 per cent allowability in it to make architecture,’ explains Cany Ash, founding partner of Ash Sakula, which worked on the first homes with Whitby Wood and Periscope. Resulting designs have ‘a whole host of subtly different plans’, says Ash, and include houses, one with double-height spaces, and apartments in a building designed to resemble a subdivided country house.
Terraced homes are bookended by engineered timber structures to provide essential additional structural stability, and such systems will probably be sourced from overseas. ‘We’re using the materials which take a little bit more carbon in the most efficient locations,’ explains Harrison. ‘We’ve advocated the approach across the whole scheme, because we found in parcel one that it was the sensible way to go.’
Apartment buildings of up to five storeys are likely to use mass timber and be designed and detailed in a similar way to Waugh Thistleton’s New Model Building. Timber composite panels, insulated with wood fibre, hemp and lime, and tinted lime render also feature on the sustainable specification.
Since writing the playbook for the Phoenix, Harrison has created more for other projects. ‘We look at a site and find all the local industries, materials and supply chains that have MMC opportunities,’ she explains. ‘Perhaps there are obvious links there, like a university with a great robotics lab and a really amazing forest and those two should be working together.’
These approaches may be different to some of the large-scale MMC initiatives backed by government, but they provide food for thought when considering MMC’s future.