One foot in the past

Bespoke prefabrication
Daniel Libeskind has entered the prefab market with a designer version – but only traditional skills can build it

­Prefabrication, as has been shown in this issue, has traditionally been associated with both ubiquity and mass production. But as ‘starchitect’ Daniel Libeskind proved with the launch of his ‘Libeskind Villa’ late last year at the corporate HQ of German firm Rheinzink in the small village of Datteln in Germany, prefabrication is just as applicable to the one-off and exclusive.

Swiss developer Proportion has been set up to commission and market the Libeskind Villa, a zinc and glass complex crystal form of timber frame and solid panel construction, using the latest ground source heating and cooling, with very high thermal performance, and rainwater harvesting. This comes hand in hand with high specification – the house is equipped with en suite bedrooms, games room, wine cellar and a sauna, and Libeskind has personally designed or specified all the fixtures and fittings. Yet only 30 of these €3m, 515m2 prefabricated homes will be built in the world, and regional exclusivity has been assured by the developer.

It must be the first time that luxury real estate specialist Christies Estates has had a prefab in its portfolio, but as Michael Merz, director of Proportion, says: ‘We wanted to investigate the apparent contradiction between the high end market and the nature of prefabrication’. But he also admits that prefabrication was not adopted as an end in itself, but as a means to an end.

‘We were looking at how we could minimise on-site construction risk, and optimise the build and finishes quality, as well as allow the Villa idea to accommodate regional differences and materials within a common structure’, he adds. That said, Merz emphasises that the designs are one-off and bespoke, and will require hand finishing by the skilled craftsmen who will put the villa together. However, ultimate design control, claims Merz, will be exercised from Libeskind’s New York office, and involves using the latest modelling and rendering technologies to allow changes so that the prefab can, if needed, be ‘re-fabbed’.

‘Our notion of prefabrication carries with it industrial baggage, compromised both in quality and cost’ explains Daniel Libeskind Studio principal Yama Karim, ‘But the Libeskind Villa is about creating a custom fabricated house that can be duplicated many times. In this case the use of prefabrication should not be seen as a compromise, but as a means of assuring higher quality and control,’ he says.

Using timber also brought sustainability benefits, with the panellised construction calculated to use 130 tonnes less CO2 than conventional building methods. In fact, the only exception to the timber system is the reinforced concrete wall at the centre of the building that supports the main steel staircase and serves as a horizontal bracing element for the panellised construction. Karim explains that the development of the panellised timber system was first modelled in Rhino to realise its geometry, and sent on to the engineers to calculate the various stresses and loads. The design was then passed to the fabricators.

This was made more complex by the fact that the Villa’s geometry is actually made up of three intersecting geometric volumes, any one of which can be removed to reduce the house size and change its configuration and look. Each of the timber volumes therefore had to be engineered to maintain its own structural integrity. These were interrogated in Rhino and then converted to 2D AutoCad files of flat templates which were sent to the fabricator for production. Karim is keen to point out that the software has been used to define the aesthetic rather than generate it. ‘The technology is great for visualising. We haven’t used it to design, but it has made it easier to compute,’ he explains, adding: ‘We see computer technology not as delivering the design, but merely facilitating it’.

The wall elements of the Villa are OSB boards over a timber frame, whose joists, posts and beams are made of solid structural timber. Because the walls run at different angles, and no two are the same shape or size, detailed planning was required to guarantee the dimensional accuracy to ensure the successful prefabrication of the 53 separate wall elements, the smallest of which is 1.3 by 3m and the biggest 12m by 5m.

Thomas Bühlmeyer of German firm Rheinzink, who supply the zinc cladding for the Libeskind villa, and at whose HQ the sole built example is sited, says that to communicate the information to the fabricators, all the data in Rhino was then converted to 2-D Autocad files and fed to them. Rheinzink wished to use its own structural fabricator, Holzbau Josef Pieper, which modelled the design using Abbund software from German firm S+S Datentechnik, a specialist in the 3-D modelling of timber structures. This was then used as the template programme for CNC cutting of the timber elements. CNC technology was employed to guarantee precision trimming that would have otherwise required many manhours to achieve.

Interestingly, to join the solid elements of the panels, the engineers decided to use traditional carpentry techniques like mortise and tenon and dovetail and lap joints, employing gusset plates only for ‘face on’ –  planar interfaces that are exposed to higher amounts of stress.

‘It was curious because even though it was a famous architects and a modern language for the building, we still resorted to traditional methods of jointing the panels’, says Bühlmeyer. ‘The problem was that the building had a lot of skewed, rather than ‘face on’ interfaces, which meant there was limited scope for the use of gusset plates, and a greater requirement for the more ‘craft based’ mortise and tenon and dovetail joints. The truth is that the extreme geometry was not really suited to new production methods’. 

Bühlmeyer is effusive about the idea to prefabricate, but feels that there was a gulf between the parametric models used to design the villa and the basic craft methods employed to build it.

‘The geometry, it seems, was not consistent with modern production methods. In the end, the idea did not make the leap to investigate new methods of production and construction to optimise the buildability of the design, so the house was constructed using traditional crafts rather than according to modern methods of construction’ (MMC).

This is borne out by the fact that the fabricator claims that there was very little direct liaison between it and the Libeskind office once the 3D design model’s files had been sent on to Rheinzink.

Asked if there were any changes that he would make to the design to increase ease of construction, the engineer reserves judgement, pointing out that this is the first villa to be built and therefore aspects that might be improved are yet to be singled out and investigated.

‘Spatially this is a great building,’ he says. ‘But how to build it better is something that we will only be aware of after we have built a number of them’.

So time will tell if the construction process can be further refined. Project architect Karim says that: ‘when we were developing the 3D model, the design was no different to any other form of product design – be it furniture or house, as geometry is scaleless, whether it’s a piece of furniture or a house’. In principle, this may be true.

But while the 3D rendering might have allowed them to understand the complex geometries of the Libeskind villa, it has yet to resolve the interfaces fully using MMC means. In this case it seems that the high-tech design and prefabrication of the panels has yet to truly rationalise the methodologies of their connection. The villa remains an industrialised house whose construction relies on traditional skills that remain firmly in the hands of the craftsmen building it.­­