Friday, August 19, 2005

What's Belgium got to teach us about housebuilding?


To British students of modern manufacturing methods, Danilith are known (if they are known at all) as the Belgian housebuilders with the robot bricklayers. But that is only a small part of the story. For Danilith is a vertically integrated housebuilder of the type that just doesn’t exist in the UK. They are a family business that has been running since the 1920s and they own a large plant in Wortegem, which they use to build as much of their houses as they possibly can. Not only do they prefabricate wall, floor and roof panels, but they make their own joinery as well. They employ 260 people, use very few subcontractors and they undertake around 250 projects a year, mostly individual homes in Belgium and Holland, mostly fully finished.

Let’s just consider this last sentence. 250 houses built each year by 260 people. That, in itself, is remarkable. No one at Danilith works more than an 1800hour year if they can help it — Belgian overtime is very heavily taxed so there is an incentive to stick to the contracted hours. Of these 260 employees, just 30 work in the factory, another 100 on site erecting and finishing the houses and the remainder in various admin roles. So essentially, 130 workers are building over 200 houses each year. That’s just under 1200 hours labour going into each house. In comparison, the standard British site-built home takes 3000 hours to construct. Danilith workers are thus over twice as productive as their UK equivalents.

This is reflected in the prices charged for Danilith’s homes. Their brochure shows that the selling price is almost always under €1,000 per sq m (£690/m2). But in Belgium, new homes attract VAT at 21%, which is included in this figure. It also includes 4% taken for design fees and a mandatory 1% fee payable to a private security firm to oversee the construction sites. The net sales price is in fact just €800 per sq m (£550/m2). It’s difficult to see something of equivalent quality in the UK costing less than £900 per sq m. In fact most MMC advocates say that you can’t build at less than £1,000 per sq m unless you are constructing identikit houses in long production runs. But Danilith’s homes are all different, although the elements used to put them together are modular.

In so doing, Danilith produce a very high quality house. We are used to seeing timber and steel framed houses built in factories but Danilith work mostly with brick and concrete, reflecting the prevailing preferences in the Benelux countries and France. The 10metre-long wall panels passing through the Danilith plant are not unique: in Germany, basements are commonly constructed with prefabricated walls. But Danilith have added to this a robotic brick laying machine which first slices the bricks in two lengthwise and then lays them face down on a flat bed, against some retardant paper. Mortar is subsequently brushed into the joints from above before three more layers, concrete, polyisocyanurate insulation board and lightweight concrete are added to the beds, the whole process taking around four days to cure and the final wall thickness being around 250mm. Finally, the walls are hoisted vertically, to be finished by hand on the last of the production lines. Windows, doors, electrical channels and plumbing runs are all set into the walls as they are being constructed. You can view the 15 stage process on the website www.milbank-danilith.co.uk. Floor panels are constructed elsewhere in the plant. Roughly a house a day passes through the plant: on a traditional British building site this would represent the efforts of around 600 hours work. In the Danilith factory, it’s 25 workers on an 8-hour shift: 200 hours. Plus, of course, a lot of investment in machinery and forty years worth of know-how.

The technology used by Danilith is far from hi-tech. It’s the sort of thing that is used on production lines across the globe. Parts of the process are still carried out by hand and compared to the latest robot car builders it all looks a little primitive. And there are many other smallish housebuilding businesses in Germany and Scandinavia using similar finished-panel systems. However, in the UK, the nearest we come to factory production in housing are the numerous timber frame companies who semi-fabricate wall and floor panels, sometimes referred to as open panel building. This requires insulation, services and finishing on site, both internally and externally.

Danilith see themselves as custom homebuilders first and foremost. Although they make windows and staircases, as well as the wall panels, they don’t sell them to third parties; they only supply their own projects. However, they do undertake a little spec. building from time to time but usually to fill gaps in the production schedule that would otherwise have them laying off staff. This is quite revealing in itself. It’s frankly hard to imagine a British firm adopting such an attitude. Indeed, it’s just the sort of action that shows the gulf between Anglo-Saxon and Continental business practice. Whilst we are busy cutting costs and growing market share, the Belgians are putting the interests of their workforce first and foremost. Whilst many British economists would highlight Danilith’s working practices as being a prime example of Eurozone featherbedding, they would also have to admit that it’s resulted in productivity levels which we in the UK can only aspire to some time in the not-so-near future. The Belgians are clearly doing something right.

This remarkable company would like to transfer some of its know-how to Britain. They have found a willing partner in Milbank, who, like Danilith, area a family-run company with a keen interest in masonry prefabrication. Milbank are big in precast flooring in South East England and have slowly grown their business to embrace haulage and joinery. But they are not housebuilders. Both Milbank and Danilith are keen to start building homes in the UK but there are significant obstacles to overcome in order to establish a British version of Danilith.

Perhaps the biggest problem is that there simply is no tradition of custom home building in the UK. On most of the continent, custom home building is the principal route by which detached houses are built. Individuals buy plots — relatively cheaply — and commission a new house to be built on them, without spending a great deal of time working on the project themselves. In Britain, the new homes market is dominated by speculative builders who build solely for sale: there are around 15,000 individual homes built each year but most of these are taken on on a semi-DIY basis with the selfbuilders acting as their own contractors. The burgeoning timber frame sector prefers to offer a water-tight shell option and lets the selfbuilders finish the houses off in their own time. One or two Continental companies offer a full-build service, notably Huf Haus and the Swedish House Company, but they only account for a tiny number of new homes each year, probably under 100 in total.

Typical of Continental custom homebuilders, Danilith is set up to build one-offs. Everything in the Danilith system is modular but provided the design fits the modules, almost any design can be built. They don’t aim to achieve economies of scale by mass production: their goal is to simplify everything down to a set number of options and to avoid prototyping. That way they avoid mistakes and they keep costs to a minimum, without becoming too repetitive.

Quite why the major British housebuilders have failed to take up factory-building Danilith-style is a mystery. Their pattern book approach to housebuilding, combined with the guaranteed volumes, ought to lend itself to prefabrication. But for some reason vertical integration has never appealed to British builders and no one has ever seen fit to try. The only plc housebuilder to currently use a significant input of prefabrication is Westbury, who have built the largest timber frame plant in Europe (Space 4) to supply some of their new homes. But Space 4 is a long way short of what the likes of Danilith and Huf Haus do.

The big question is this. Can the cost savings shown by Danilith be achieved simply by copying the technology or is the different business culture an essential part of the mix? Whilst it ought to be easy to introduce robot bricklayers, it will be much harder to integrate the Continental work ethic needed to keep the robots ticking over. Mark Brinkley

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Thursday, August 18, 2005

Cleve Prior Webcam


Many selfbuilders have run websites, photographing and recording their builds along the way. But this is the first one I have come across where a webcam has been installed so you can watch the action "live." The house is in Lancs and is being built by Tim and Val Fairless, frequent contributors to the selfbuild list. The webcam isn't quite as gripping as the cricket, but it's tempting to leave it on it the corner of your screen. As the caption says "If the image does not move, then nothing is happening."

www.timval.com/webcam.html

Mark Brinkley

Building a basement: how to keep it dry

I need lots of information on building a basement. I'll take anything from construction, design, good build, bad builds, tanking, damp proofing, companys, as I said, anything. My project is to build an art studio with a basement measuring 30 feet long by 20 feet wide, going down 6 feet to subfloor leaving two feet about ground level for windows and vents.

Thanks Mostyn Powell

Housebuilder's Bible author Mark Brinkley reckons:

The one thing that people really fear, when considering basements, is that they will leak. And it's not a groundless fear. The insurance claims records on new basements is appalling, enough for insurance bodies like the NHBC and Zurich to often specifically exclude basements from their cover. The problem is that relatively minor errors can result in total failure whereas above ground they would most likely pass unnoticed. And of course leaky basements are difficult and costly to fix.

There are basically two techniques for stopping basements leaking: tanking and drainage. Ideally both should be employed. There are several ways of building basements and they are all potentially excellent yet none of them is completely foolproof. You need an appropriate design to start with and you need to employ contractors with above average competence.

One of the problems with basement design is that no one quite knows who to talk to at the outset. If you go to a "basement specialist" they will most likely be trying to sell you their pet system, regardless of whether it is suitable for your site. An architect? Probably won't have a clue. Neither will most structural engineers. An "experienced groundworker?" You may be lucky, you may not, not many UK groundworkers have ever built a basement. You could do worse than check into the Basement Information Centre www.basement.org.uk and key into their database, although it keeps throwing up Phil Hewitt as the only independent consultant philhewitt@btconnect.com

One other tip,
Selfbuilder Lol Berman is just completing a new house in Cambs with a 17x8m basement. He costed out four options at the outset:
• ThermoneX £77k (ThermoneX make prefab basement walls, craned into position)
• Beco £56k (Beco are an ICF business, using polystyrene moulds into which concrete is poured)
• Ordinary Local Groundworkers £58k
• David Ball's Pudlo System £41k (Pudlo is a waterproofed poured-in-situ concrete system produced by the David Ball Group www.davidballgroup.com)

He went with the Pudlo system and thus far it's been fine.

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Friday, August 12, 2005

Sasmox

David Birkbeck’s use of the Finnish building board Sasmox as a wall/ceiling board is unusual. The UK selfbuild community are keen users of Fermacell, a similar product, made in Germany, and I was interested to make the comparison between the two boards. Sasmox is slightly more expensive than Fermacell: a plasterboard:Fermacell:Sasmox cost ratio would go 1:3:3.5 or maybe that should be 2:6:7. It’s a very simple product made of spruce cuttings (of which Finland has no shortage), waste gypsum and water: it’s pressed together in stainless steel clamps, there are no glues or additives. Whereas Fermacell doesn’t really like water — it tends to belly — Sasmox is virtually unaffected by it. Where Sasmox really wins out over Fermacell is with the finish: it’s smooth and shiny, doesn’t really require any painting other than filling between boards and over screw holes.

The downside of all these heavy boards (Sasmox weighs 1250kg/m3, about 40% more than plasterboard) is that they are really not easy to work with. You need a jigsaw to cut them rather than just scoring with a Stanley knife, plus you really struggle to get the boards onto ceilings simply because they weigh so much.

Sasmox is distributed by the Panel Agency www.panelagency.co.uk, Tel 01474 872578. The contact is Roger Kingsley who is happy to deal with largish (whole house) orders direct. Mark Brinkley

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Chateau Birkbeck nears Completion


Mark Brinkley writes: Friday morning, drive down to Thaxted to see how David Birkbeck’s new house is coming along. David was the first editor to hire my keyboard, back in 1996, and now he runs a consultancy called Design For Homes which sets out to get housebuilders to hire architects. He is in the middle of his first selfbuild and I have been following the story ever since he first put an offer in on the plot. The house is, naturally, very designey: the architects are Snell David. I was last here in January when the extraordinary spine wall was taking shape with these unusual blocks, which are glue-mortared.

Now the house has taken shape around it and it’s a magnificent structure. It’s a magnificent site, which helps matters; a sort of woodland glade with a large pond and the house has large glazed panels looking out over the pond. If I was feeling critical – and I’m not today – I could say that it suffers from being an architect-driven project, which is overly complex and unnecessarily fussy. But on this balmy August day, it just looks very cool and comforting and, indeed, just a little inspiring. David isn't on site but he speaks to me over the phone and enthuses about the whole structure being both very modern yet very Essex. I think he's referring to the timber wall panels but even these turn out to be something unusual, in this case Thermawood, a heat treated softwood which should last decades, "unlike all that nasty cedar," he says "which is already beginning to look tatty." David can be very funny; whilst he works as a champion of good house design, this doesn't mean he champions ALL new house design.

Like most selfbuilds, this house seems to be being assembled by all kinds of odd people. I am met and tea-ed by Clare’s brother who is about to become a primary school teacher. Upstairs are two lads who normally work as exhibition display builders: they are putting Sasmox building board in place on the many studwork partitions. This is a non-traditional skill if ever: no one here has ever worked with Sasmox before. It’s heavy and a little fragile but it doesn’t need finishing, unlike plasterboard.

The scaffolding is about to be struck and David says he hopes to be in within “a few weeks.” Having knocked about the selfbuild scene for many years, I should know that this is wildly optimistic but sometimes you can’t help but be dragged along by all the optimism.

Monday, August 08, 2005

UK Land Use Statistics

The following text is taken from a short article by James Woudhuysen, Professor of Forecasting & Innovation at de Montfort University. It appeared in the Housing Forum Newsletter. James tells me that he drew it from The Office of National Statistic. He also tells me to mention his book "Why is construction so backward ?", John Wiley & Co, 2004.

In Britain 57.5m people live in about 24m dwellings. If household growth is to match population growth, 64m people will, by 2030, need a stock of 26.7m homes. But households are getting smaller, so call that 2030 total for homes 29m – five million more homes than exist in Britain in 2005.

Then there is the rate of stock replacement. Today, ordinary flats or houses will just about last 100 years – given lots of refurbishment and DIY. So take it that, over the next 25 years, Britain will need to replace, on a 100-year cycle, stock that rises from 24m to 29m units. That means building an additional 242,000 new homes in 2006, racking up to 290,000 in 2030. Over 25 years, therefore, 6.65m new homes will be needed just to replace worn-out old ones. Add the 200,000 homes required for annual new household formation to the average of 266,000 required for annual stock replacement and one gets an annual output of 466,000 homes –11.65m over 25 years. That’s a little different from the annual average of 171,225 homes built in Britain since 1997.

Wouldn’t the millions of new homes we propose concrete over Britain’s green and pleasant land? Wouldn’t they mean, at the very least, still more urban sprawl? It’s time to lay these myths to rest.

The land cover of Great Britain is 23.5m hectares, used in 2002 as follows:
• 1. intensive agricultural land – 10.8m hectares, or 45.96 per cent
• 2. semi-natural land – 7.0m hectares, or 29.78 per cent
• 3. woodland – 2.8m hectares, or 11.91 per cent
• 4. settled land accounts for 1.8m hectares, or 7.65 per cent
• 5. water bodies – 0.3m hectares, or 1.28 per cent
• 6. sundry other categories – 0.8m hectares, or 3.42 per cent.

If settlements are added to the ‘sundry’ component (largely transport infrastructure such as roads and railways), then built-up Great Britain consists of about 2.3m hectares, or just 10 per cent of the land available. Clearly, considerable growth in both population and household numbers can be accommodated – both in high urban concentrations, and as dispersed settlements integrated into the landscape. Mark Brinkley