Topping out
Gerald Cole
Prefabulous
Don’t be scared of prefabs
Thirteen-odd years ago, at the invitation of a couple of house building companies, I flew to southern Germany to visit their factories. Did you notice anything unusual about that sentence?
To the average Briton, which includes most newcomers to self build, the idea of a housebuilder owning a factory can seem a little odd. Don’t housebuilders build houses on site? We’ve all seen mechanical diggers gouging out foundations, big lorries delivering ready-mixed concrete, scaffolding rising as walls follow, block by block, brick by brick.
How can you do all that in a factory? Well, a little later into your self build journey, you’ll encounter timber frame manufacturers. Unlike most UK commercial housebuilders, who still build with bricks and blocks, timber frame specialists do have factories. There, they construct the wooden frames which provide the structural support of a timber-frame house.
Timber frame manufacturers have regularly targeted selfbuilders by stressing the virtues of their construction method. Because it’s prefabricated, a timber frame can be erected on site within a few days, rather than the weeks it takes to build a blockwork shell. Timber is more thermally efficient than masonry and the internal walls are dry plasterboard, ready for immediate decoration.
But that’s not the entire story. Timber frame manufacturers’ brochures typically show completed examples of their standard designs. Generally, however, it’s only the underlying, and invisible, structure that’s for sale. The brick exterior, roof tiles or slates, doors and windows – not to mention the foundations on which the frame sits – are usually down to the customer, or their contractor. Undoubtedly site time can be saved, but an awful lot of work still has to be done there.
Which brings me to Germany. In the early noughties I visited WeberHaus and Baufritz, both timber frame specialists, as it happens, and both now operating in the UK. They were a revelation.
Each had a large factory, where homes were prefabricated in storey-high wall panels, complete with insulation, exterior and interior finishes, plumbing, electrics, doors and windows. At the end of this process, the panels were delivered to site on a small convoy of lorries and could be assembled on a prepared foundation and made weather-tight in just three days.
Each company included a park of show homes of both standard and bespoke designs, There was also a design centre, where in-house architects could provide original designs or adaptations of clients’ own ideas.
The same centres also featured what were essentially self-build supermarkets, displays of virtually every item required to build a home, from central heating systems to roof tiles to door and window fittings. Clients were encouraged to spend up to a fortnight visiting and selecting every interior and exterior feature of their home. As a result, plans could be produced of such thoroughness that both a fixed price and a fixed schedule could be guaranteed for their project.
Henry Ford moment
Thirteen years ago this level of efficiency and customer involvement put Britain’s ad hoc, subcontractor-based, take-it-or-leave-it housebuilding industry to shame. Here, it seemed, was housebuilding’s Henry Ford moment, when homes could become as reliable, customisable and thoughtfully designed as cars.
So, 13 years on, how much closer are we to that? Well, the most significant change has been the growing acceptance of prefabrication. Also known as ‘off-site’ or ‘modern methods of construction’ (MMC), it comes, broadly, in two forms — ‘flat pack’, where storey-high panels or complete walls are factory-made then assembled on site, and ‘modular’. Here, finished segments, including whole storeys, are prefabricated, delivered to site, then simply bolted together.
However, only around 15,000 of England’s 195,000 homes built last year involved either form and most were for social or student housing. Self build accounted for only a small proportion — mainly high-end properties by companies such as Huf Haus, Baufritz, WeberHaus and Dan-Wood. Bedfordshire-based Potton, with its five-house show park, and self build academy is perhaps the nearest UK manufacturer to the all-inclusive German system.
But this is only the beginning. The numbers of skilled tradespeople on which traditional construction depends are steadily dropping. Retirees are not always replaced; others are departing post-Brexit.
Meanwhile, Legal and General has completed the world’s largest modular housing factory in Yorkshire, aiming to produce 4,000 homes a year. Also in Yorkshire, Ilke Homes has opened a factory producing two- and three-bedroom houses, priced from £65,000 to £79,000, plus land and assembly costs. Delivered with kitchens and bathrooms already fitted, they can be erected on site within 36 hours.
Among smaller prefabricated suppliers are Urban Splash, Facit Homes, nHouse and ZEDPods, which is currently seeking planning for 65 affordable, low-carbon starter homes across the UK.
Again, most, but not all, are targeting volume customers rather than individuals, but the facilities and skills are all seeding future opportunities and quietly, but effectively, off-site is gaining ground.
It may not be the answer to everyone’s housing needs. Making last-minute adjustments to plans is likely to cause problems, delivery to remote or awkwardly sited plots may not always be possible; lenders and building control departments are still instinctively wary of ‘non-standard’ designs.
But prefabrication is well established elsewhere, from Scandinavia, where 45% of new builds are manufactured off-site, to Japan, where factory-produced homes have been common since the 1950s. It promises houses that are not just better built, more energy efficient and more sustainable, but can save up to 40% on existing average build costs. Even the government has recognised the value of this and is providing £204m to fund innovation in the construction industry.
It’s simply the easiest way to date to provide the value, cost effectiveness and reliability consumers have come to expect in every other major purchase, except, bizarrely, the largest, most important one in most of our lives.