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A recent study tour to see Japanese prefabricated housing found that the whole of housing provision is being transformed Learning from the Japanese

TECHNICAL

The government, which funded this tour, has expressed an interest in timber-framed house prefabrication for the uk for several reasons - productivity, sustainability of the timber, waste minimisation through industrialisation, site-skills shortages and customer choice.

Japan's new-build market is about eight times the size of the uk's at around 1,500,000 units per year. The five biggest players have a combined turnover of £20 billion, providing a big finance base for investing in production improvement. And they - Mitsui, Misawa, Sumitomo, Daiwa, Sekisui - are part of conglomerates of wide commercial experience.

Currently about half of new-build housing is apartments, half detached. The tour focused on the latter. Some detached houses are on new urban estates with interior space standards at least as high as the uk. Others are replacements of existing houses on the same (highly expensive) site while the occupants stay in a hotel or with relatives. This creates pressure for fast construction and thus for prefabrication. Another pressure comes from skills shortages. Japanese construction is known as a 3D industry - dirty, dangerous and dull. Around one-quarter of new houses are currently prefabricated to some degree.

The house market is large partly because the average life of a house is only around 25 years. Culturally, housing is not seen as a long-term investment. Consumer surveys also show that existing houses are often of poor constructional quality with poor thermal and acoustic performance, lack storage, and are cramped and in disrepair. However, there is now a push to increase house life, with one company floating the novel Japanese concept of the 100-year house.

Prefabrication

Detached houses are traditionally post and beam with elaborate hand-cut joints - this cutting alone can take 30 man-days. The simplest level of prefabrication is the machine-cutting of timbers to size, plus joints, in one of 800, often small, workshops. But the tour group found no great time or cost savings from this degree of prefabrication.

Platform frame systems of prefabricated timber stud panels and some steel- framed alternatives are the other main forms of prefabrication. These are more successful. That success, though, is not a matter of improving productivity in isolation. Rather, cad/cam-driven prefabrication was part of a broad-based package providing a new sort of customer choice.

Customer focus

For a new customer, the house-buying experience can begin at a housebuilder's customer centre or a show village. These are not particular to prefabricated housing but include all construction approaches.

Rather than show houses on building sites, independent organisations set up show villages of 10-100 houses from different housebuilders. Smaller villages may be on a theme, such as traditional timber housing. Typically, villages are alongside shopping centres or other attractions. Visiting them may be part of a day out. There are around 800 in Japan and major housebuilders will be present on 400-500 of them, in each case represented by a well-qualified salesperson. (One home-grown uk version is currently planned, aj 3.10.98 p49.)

There are also housebuilders' customer centres, where the big companies show off their research and development capabilities, sell the idea of high-quality, high-performance buildings, and through cad offer customers a wide design choice. The Daiwa centre, for example, includes a 400-seat lecture theatre, presentation rooms, library, overnight accommodation, a theme pavilion on housing development, including a variety of models and full-scale houses, design sessions and 3D computer walk-throughs of the results. There are tours of the labs - many Japanese have proved responsive to the idea of technological innovation in housing. The customer can leave after half a day carrying a set of design drawings.

After construction, builders often make quarterly after-care visits to the house over two years. Current guarantees are at best for 10 years, but at least one company is considering 20.

All this customer service, in a highly competitive housing market, comes at a price. It costs 13-25 per cent of the final sales price (excluding site cost) compared with around 4 per cent in the uk. This also excludes the cost of research and development. The big five together spent £90.8 million on it last year, some 0.45 per cent of turnover, focused on customer need and staying ahead of competitors. This percentage is a feasible expenditure for uk companies. Given the relative size of the uk and Japanese markets, it could make sense for some uk firms to pool resources, both to reach a critical mass of effort and because there appears to be a lot of duplication among the competing Japanese companies.

Other pointers for the uk are that, given the opportunity, customers may be a lot more open to innovation than housebuilders typically portray them. What remains less clear after this fact-finding mission is how central to it is prefabrication. Much of the Japanese customer experience could be replicated in the uk without prefabrication, though not without more extensive use of it and r&d. Admittedly our lack of site skills and hence quality is an increasing problem.

Industrialisation is bound to increase in the uk. But starting from the premise that prefabrication as it exists is the answer, without being clear what the question is, cannot be the best way to proceed. One Japanese lesson is to begin with the customer, not the technology.

* House from the Rising Sun. Research report 1/98. trada Technology, tel: 01494 563091

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