Pump up the volume

Volumetric construction has always had a bit of an image problem. Both clients and the public at large are suspicious of its boxiness – OK for budget hotels, student housing or relocatable site huts maybe, but not the kind of thing a big-name architect would want its name attached to or any family would want to live in.

Over the next three pages, we showcase some of the most recent developments in volumetric construction, from a cunning use for Chinese shipping containers to some much needed architect-designed curviness.

It is particularly noteworthy that many recent innovations are taking place in the housing sector, with companies such as Spaceover trying to repackage modular homes as an upmarket lifestyle option.

They have their work cut out: currently, volumetric construction produces no more than 350 housing units a year, a mere 0.2% of the total national output. “For most housebuilders, moving nearly all production from the site into the factory is too big a psychological hurdle,” says Darren Richards, managing director of off-site consultant Mtech.

The way forward, Richards argues, is to emulate the car industry by introducing “mass customisation”. He urges companies to adapt designs instantly to customer needs by harnessing the potential of new flexible computer-aided design and production systems. That is, he says, the only way modular companies will make their products truly popular. Until then, some forward-thinking companies are doing their best to make that hurdle look less daunting.

Yorkon / Curves are in

Design and technology: Yorkon has set itself the goal of breaking the image of crudely repetitive, boxy volumetric modules. Instead, conceptual design studies commissioned from architect TP Bennett show deep-plan, curvy buildings and blocks with jagged outlines of projecting and recessed volume. Technical improvements have increased clear spans of steel-framed modules from 8m to 12m and their self-stacking capability from four to six storeys.

As a result, curved buildings with faceted facades can be created by arranging wedge-shaped modules alongside each other. For instance, 18 modules each with a 10° taper will together produce a semi-circular block. Complex megastructures can be assembled by slotting volumetric modules, and other architectural elements, with gaps in between, into a structural frame.

Back at the well-equipped company plant in York, more efficient computer-numerical-control-cutting systems and tighter tolerances have reduced material wastage in offcuts by up to 50%.

Benefits: “We have developed a series of exciting yet practical concepts to inspire architects, contractors and clients,” says David Johnson, managing director of Yorkon. In particular, the company wants to break into building types not usually associated with volumetric construction, such as multi-storey high-spec offices and larger retail, leisure and education buildings. At the same time, Yorkon and Bennett want their buildings to celebrate modern prefabrication rather than conceal it behind conventional facades. Not least, reduced wastage of materials should lower construction costs.

Output: Once it has persuaded more people of the benefits of new modular technology, Yorkon plans to roll out mould-breaking buildings as an increasing proportion of its output of 60 modules a week.

Cartwright Pickard/Genesis / Murray Grove writ large

Design and technology: This affordable housing block in Islington, north London, is the sequel to the ground-breaking Murray Grove scheme of 1999. It shares the same original developer, the Peabody Trust, and architect, Cartwright Pickard, although Peabody sold the scheme on to Genesis Housing Group. The project’s main innovation has been to extend volumetric dwellings upwards to form three-storey maisonettes, and to use larger modules than in Murray Grove (up from 8 × 3.2m to 10.4 × 3.8m).

The modular construction is celebrated in eye-catching chequerboard facades of beige faience tiles alternating with indigo-blue render. The modules were manufactured by Caledonian Building Systems and the development, built by Kier London.

Benefits: The three-storey maisonettes cater for families, who make up a large proportion of househunters and have been struggling to get on the central London housing ladder owing to the shortage of large homes.

Output: It contains six three-bedroom houses on the lower three storeys and 23 deck-access apartments in the top two.

Verbus / The ‘hotel in a box’

Design and technology: Verbus, a joint venture of engineer Buro Happold and contractor George & Harding, has adapted hotel room modules from standard shipping freight containers. The modules are manufactured and fitted out into shower rooms, beds and electrics by a shipping container manufacturer based in Xinhui, China. The modules are made of robust profiled Corten steel, which means they can be transported long distances without damage. They can be stacked up to 12 or even 16 storeys high and feature a locking device to prevent vibrations from passing from one hotel room to another. They are also robust enough to be demounted and reassembled elsewhere.

Further design developments will modularise all other hotel elements, including foyers, kitchens and building services. To form the lift shafts and staircases, upright, open-ended modules, one containing the lift cabin, will be stacked on top of each other.

Benefits: Cheap prefabrication in China undercuts conventional hotel construction costs by 10%, according to Paul Blackmore, Verbus’ managing director. Extra savings of 5% are anticipated by the modularisation of the entire hotel package. Rapid mass production of up to 300 modules a day and shipping from Hong Kong could deliver modules all over the world in just 10 weeks and enable total hotel construction in 16 weeks.

Output: The first ‘hotel in a box’ of 121 bedrooms in a 10-storey block above shops is being built for Travelodge in Uxbridge, west London. The global roll-out is planned to come on stream next year. “We could build up to 20 hotels in eight or nine different countries for one or more international hotel operators,” says Blackmore.

Spaceover / Seal of approval

Design and technology: Spaceover, of Nottingham, manufactures the only volumetric modular system to have won accreditation under BRE’s LPS2020 standard for innovative methods of dwelling construction.

Gaining accreditation costs about £10,000. As well as covering the Building Regulations, LPS2020 addresses durability, ease of repair, whole-life performance, adaptability and resistance to fire, flooding and break-ins. Modules with light-gauge cold-rolled steel frames are manufactured by Ayrshire Metal in Daventry and fitted out by Rollalong in Wimborne, Dorset.

Benefits: “As LPS2020 has the backing of the Association of British Insurers, the Council of Mortgage Lenders, the Housing Corporation and the National House Building Council, we get the cost of accreditation back in lower premiums for project insurance,” says Tony Fox, director of Spaceover. “Housebuyers also benefit from lower buildings insurance.”

Output: Two accredited schemes, totalling 125 dwellings, are under construction, although they conceal their modular nature behind traditional brick walls and slate roofs.

In Harlow, Essex, volumetric modules are being used for conventional two-storey houses for the first time. Here, architect Proctor Matthews won a design competition for the Meehan brothers’ New Hall neighbourhood with a proposal for 78 stylish terraced and semi-detached houses for sale and equity sharing.

Elements Europe The ‘co-pod’ system

Design and technology: Instead of assembling dwellings entirely out of volumetric modules, Elements Europe has adopted a hybrid construction system, with Mtech Group as consultant. The company supplies prefabricated bathroom, kitchen and services-stack pods, around which the builder erects the rest of the house using prefabricated flat-pack frames of galvanised hot-welded steel. The pods are structurally self-stacking and provide rigidity for the entire steel-framed shell. Another system of “co-pods” combines bathroom, kitchen and staircase into a single pod at the centre of an apartment, with an entire single-bedroom apartment selling for just £67,000.

Benefits: Bathrooms and kitchens, which are the fiddliest construction elements in a house, are prefabricated in a factory for quality and speed of construction. As a result, dwellings can be built in 16 weeks with fewer defects, though at no extra cost, claims Wayne Morgan, managing director of Elements Europe. An in-house design team linked to flexible CAD/CAM production offers mass customisation or easy variation of the pods.

Output: Elements Europe can fabricate and fit-out 50 pods a week at its Shropshire plant and deliver them all round the country on its in-house fleet of articulated lorries. The hybrid self-stacking system has already been used for two-storey houses and is currently being used for a five-storey block of 39 apartments in Liverpool.