Japanese automotive production methods have influenced the world's motor industry for years. Less well known are the production methods used by the Japanese volumetric housing industry. Martin Pawley interviews Jim Meikle of Davis Langdon Consultancy and Nick Whitehouse of Terrapin, and assesses with them the potential of volumetric construction in the uk
Jim Meikle, senior partner at Davis Langdon Consultancy
Above: Multi-rise volumetric housing in Japan. Other pic: Sekisui quality low-rise housing
Although they share the same address, Davis Langdon Consultancy is far less well known than its parent organisation Davis Langdon & Everest, the international construction cost consultant. dlc is both more rarefied and more specialised, consisting as it does of a dozen or so skilled analysts and researchers with an unrivalled overview of global construction economics. Founded in the early 1980s, dlc inherited the knowledge accumulated during dle's long association with public-sector housing and has since added to it with experience of recent and current competitive methods as well as extensive international work.
Coming from a project management background with considerable international experience in housing matters, dlc's managing partner James Meikle takes a broad view of the prospects for enlarging the market for steel through volumetric construction. First he considers the evidence of market penetration so far. 'Apart from non-volumetric heavy steel structural frames, industrial cladding and steel reinforcement, we know that prefabricated steel construction of a kind has found favour with fast-food chains, motels, petrol stations, supermarkets, and even prisons in the United States,' he says. 'But we could argue that the true volumetric method itself grew out of housing, so that might be the best place to start. If it doesn't work with housing it won't work with anything else, so the first thing I would look for would be a contemporary example of volumetric steel construction in the housebuilding industry somewhere in the world.'
From this point Meikle's analysis draws on his international experience, notably a recent fact-finding mission to Japan which involved a study of six firms in the Japanese industrialised housebuilding sector specialising in timber-frame, steel-frame, steel-frame modular (volumetric), or precast- concrete systems. It was a measure of the scale of these operations that not only did the whole prefabrication sector add up to 20 per cent of the total Japanese output of new homes, but that 20 per cent equalled the total housing output of the uk. Furthermore, as much as 25 per cent of all prefabricated housing took the form of steel-framed volumetric units.
But Meikle cautions, 'In Japan, there is a prefabricated housing industry, but that corresponds to a scrap-and-build culture with little or no equivalent over here. Japanese houses are replaced on average every 25 years, roughly once in a generation. The interesting thing from the production point of view is that this rapid replacement sector is not only dominated by prefabrication firms, but that their product is bespoke housing for relatively wealthy households, not downmarket mobile or sectional homes as is so much factory-made housing in the United States.
'Of course, with twice the uk's population, the Japanese housebuilding market is huge. The construction sector of the economy alone is equal to the gross domestic product of the uk, and the housebuilding industry produces nearly 1.5 million units a year. The bulk of it is still conventional site-built timber frame building using imported timber, but it is interesting not only that this specialist market for volumetric housing exists, but that it is not small by uk standards. The largest volumetric housebuilder we visited in 1994 produced 70,000 units a year.'
As with all international comparisons, there are special factors to take into account. The Japanese volumetric homes are almost all of what might be described as a traditional Western appearance and seem to encounter no opposition from local planners. At the same time, land prices in Japan are so high that the replacement housing market is a market in housing and not in land. Housebuilders in Japan do not buy, hold and develop land; they build houses or apartments for sites that for the most part are already occupied by existing buildings. Thus their housebuilding firms do not compete for sites and subcontract their construction work, but build houses exclusively and compete on quality of product and speed of operations. With homeowners replacing their houses in situ instead of moving from house to house, the argument for rapid and precise construction - and thus for volumetric production, and thus arguably also for high- tolerance steel in preference to low-tolerance timber - becomes very strong.
As Meikle points out, housing clients with only one home cannot afford to stay with relatives or in hotels for long periods. Volumetric construc- tion, with every module pre-wired, decorated, equipped with appliances, fixtures and fittings, serves this unique market perfectly. Summing up, Meikle says, 'We might argue that where prefabrication and pre-assembly are necessary, steel construction is needed too.'
The greatest obstacle to the introduction of steel volumetric housing on the Japanese model in the uk would appear to be the cumulative effect of the very different housing policies pursued by the two countries over the last 30 years. While in the uk during that period the rate of construction has been relatively low, the rate of demolition and clearance has been low as well. As a result the mean age of dwellings in the uk is about 53 years. In Japan, the rate of new construction has been much higher, but demolition and clearance have kept pace with it, so that the mean age of the Japanese house is about 23 years.
The net result is rather as though two motorists has started out by purchasing identical Morris Minors in 1968 and, while one had been kept running by dint of continual repairs, rebuilding and after-market improvements, the other had simply been replaced every two or three years by a later model. There are arguments in favour of each system, but the state of demand determines which will be most successful. There is, for example, little or no diy industry or self-build housing in Japan - which fuels the product replacement market - while in the uk restrictive planning legislation tends to resist the demolition of any existing structure.
In Meikle's view, there are two possible opportunities for steel volumetric housing construction in the uk. The first is in the 15-20,000 unit self- build sector, particularly for sites in remote parts of the country where labour is scarce, and the second is in relation to the same top-of-the- market sector that pays for replacement housing in Japan. He says, 'Perhaps the best direction for a steel company wanting to move into housing would be to compete with volume housebuilders on the basis of a superior and faster product, or better still, to supply up-market volume housebuilders with higher quality prefabricated dwellings than they have ever seen before.'