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Structures: Home delivery

The Wikihouse open source construction system was recently put to the test in central London. Dave Parker reports on how the team of volunteers got on.

Wikihouse

Flat pack: The 4.0 version Wikihouse at the Building Centre was erected by teams of volunteers

Hailed as a harbinger of the “Third Industrial Revolution”, the two storey structure displayed outside London’s Building Centre until 26th September was the latest and largest example of the Wikihouse open source ­construction system.

The design is based on downloadable free design software that can be easily customised by users, who then send manufacturing instructions direct to CNC digital cutting machines. These produce the components from a suitable structural timber sheet material to a very high degree of accuracy.

Assembly is said to be well within the capacity of experienced DIY enthusiasts. The 4.0 version at the Building Centre was erected by a team of between eight to 10 volunteers each day from design and engineering firm Arup and architect Architecture 00. The frame was basically complete within three days and the building fit out within nine.

No permanent metal fixings were used to connect the structural elements together. Instead, a wedge type joint was adopted. “The tolerances achievable with CNC manufacture are remarkable,” said Arup director Stuart Smith.

“You can actually achieve an ‘interference fit’, where two elements are held together by friction alone. This fundamentally changes how timber structures work.”

Irish-manufactured 18mm thick SmartPly oriented strand board (OSB 3) was the structural material selected, and other board types such as plywood can also be used. OSB is seen as more sustainable than plywood, as it utilises forest thinnings as the raw material rather than larger diameter logs. In total, 380, 2,400 x 1,200mm sheets were needed, and the finished components, weighing around nine tons, were delivered to site in five Luton van loads.

Solid and economical

 

Wikihouse interior

Model behaviour: The frame of the house was basically complete within three days and the building fit out within nine

A glorified garden shed it most certainly is not. First impressions are of solidity and stability - the word flimsy never comes to mind.

Yes, the basic structure has been likened to a cross between a jigsaw puzzle and a particularly baffling flat pack bookcase, and yes, the multitude of components havebeen cut from 18mm oriented strand board, the country cousin of traditional plywood. And OSB wedges hold the whole thing together, a jointing technique that dates back at least to the Bronze Age. But there is nothing shed-like about the finished frame, and once clad and lined there will be little to distinguish it from any other modern house.

Certainly not its size. Two bedrooms, a single public room, total floor area 75m2. Typical of starter homes in 21st Century Britain, famous for having the smallest domestic housing in the developed world.

Within this miserly envelope, however, there are some neat touches to maximise usable space.

Although the whole Wikihouse philosophy is primarily focused on the self-builders of this world, this 4.0 version is a challenge not to be undertaken lightly. Expertise in the assembly of Ikea products is helpful but not enough in itself. The task is made easier, however, by the comprehensive tagging of every element, an approach that Ikea should seriously consider.

One option for the less adventurous self-builder would be to have the frame erected by professionals before taking on the rest themselves.

Such professionals are unlikely to use the downloadable mallet design, with its sharp edged rectangular handle. This caused more than a few blisters during the Building Centre erection, it seems.

Innovative developers may well be interested in the concept after seeing this prototype.

Overall, Wikihouse 4.0 takes prefabricated housing to a new level, not least in its reassuring solidity. It feels like a “real” house, and that may be the key to its ultimate success. Dave Parker

SmartPly is based on a low formaldehyde adhesive and is available impregnated with flame retardant. On this project, however, a 10mm thick Euroform Versaliner cement particle board lining provided all the fire resistance required.

Smith said there were two particular design challenges that Arup had to meet. “We needed an acceptable clear span for the living areas. And, as this system is all about self-build, we had to minimise the need to work at height.”

Wikihouse

Cellular box sections 300mm to 350mm deep made up the two floors and allowed a clear span of 4.5m. Wall sections acted as safety barriers around the first floor, creating a safe working platform for the erection of the roof structure: pitched on this project, although a flat roof design is equally viable.

Some working at height will still be required, particularly to install the roofing, and this could be delegated to established contractors. Final cladding can be anything from shiplap timber to brick slips.

More than structural innovation was on show on this project. Inside, under the stairs, was the open service zone. Here the high voltage alternating current (AC) feed from the National Grid was converted to extra low voltage direct current (DC). This supplied power to the high efficiency low voltage lighting system using standard Ethernet cabling- in fact the only AC outlet was in the kitchen.

Also on display and attracting much interest from visitors was an open source browser-based control system that has been further developed by Arup for this project using the OpenHAB system. This allows lighting and ventilation to be controlled from smartphones and tablets or even by voice, and is seen as an early step towards a new philosophy of home electronics.

It took the team only two days to carefully dismantle the building and another half day to load it onto a lorry, bound for Liverpool. There it will be taken over by the Friends of the Flyover as part of their campaign to halt the proposed demolition of the Churchill Flyover in the city and convert it into a “park in the sky”, with markets, cafés and allotments.

 

Wikihouse timeline

 

Wikihouse

First developed by a consortium of 00 Architects, programmers Espian and structural engineers Momentum Engineering and launched in September 2011, the Wikihouse project aims to do for housing and associated technologies what Wikipedia did for knowledge.

No longer will those looking for a new house be passive consumers, choosing from a limited palette offered by major house builders. Instead, they will be able to design their dream home, control the production of the structural frame, assemble and fit it out with power and lighting systems themselves.

Three key elements have come together to make Wikihouse a realistic proposition. Free open-source design software that can readily customised by the user, cheaper and highly accurate CNC machines and the emergence of 3D printing technology as a realistic manufacturing tool.

“Arup believes in the potential of digital fabrication and open source technology,” said Arup senior structural engineer Nina Tabink. “It will provide an alternative, collaborative way of working that should be more efficient.”

Since 2011, 14 Wikihouse “chapters” have been set up around the world, constantly feeding back experience and improvements. The aim is to develop a design that will allow self-builders to put together a two bedroom house for £50,000 or less - not including land costs. Tabink said the New Zealand chapter was also motivated by Wikihouse’s inherent high seismic resistance.

Domestic housing is only the start. A ‘Wikibarn’ was raised in Scotland last month, and the open source controls and extra low voltage DC systems have direct application to other buildings. What this threatens to do to the traditional design and procurement routes is still hard to predict, although the Wikihouse promoters make no apocalyptic claims.

Arup’s experience with this project has been very positive, said Arup associate director Adrian Campbell, who was also one of the volunteer erectors. “It was quite refreshing to be hands on for a change - design has been getting further and further away from making, so this gave us all new perspectives.”

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