Diary of an Eco-Builder

'Tree House will rise as the sycamore next to it begins its own new year of growth'

After our instant winter, the instant spring. Only two weeks ago the streets were covered in snow and our building site was icily inactive, but today Brixton is rammed with crowds more typical of August and the mood of our little eco-building team is significantly warmer.

After our instant winter, the instant spring. Only two weeks ago the streets were covered in snow and our building site was icily inactive, but today Brixton is rammed with crowds more typical of August and the mood of our little eco-building team is significantly warmer.

Steve Archbutt, our site foreman and principal builder, has more reasons to be cheerful than the rise in temperature - notably the arrival on site of the first components of our timber frame. Although he has spent most of the past five months digging holes, shifting dirt and pouring concrete, Steve is first and foremost a carpenter, with a carpenter's delight in the smell of sawdust on a warm spring day. The delayed delivery of our frame has been frustrating, but at least we can now put it up in a kinder and perhaps more appropriate season. Tree House will rise as the towering tree next to it unfurls its buds and begins its own new year of growth.

If "timber frame" makes you think of magnificent oak structures or the crooked charm of Elizabethan wattle and daub houses, think again. Like the majority of modern timber frame houses in Britain, our structural frame will be hidden, disguised by plasterboard on the inside and protective cladding on the outside.

Although wood will be a defining feature of Tree House, the only exposed structural timbers will be the spreading branches of Douglas fir that hold up our solar roof. As the structure can be hidden, anyone can enjoy the ecological benefits of a timber frame regardless of their personal domestic aesthetic.

Timber is, of course, a top-notch renewable material made from carbon dioxide with solar power. Timber structures tend to be flexible and adaptable, so fewer resources are needed to keep them viable over a lifetime of occupant desires (humans have different needs from cows, for example). Finally, timber frame houses are usually very well insulated. In a brick and block house, insulation is stuffed in the cavity between the blocks and the bricks, whereas in a timber frame house almost the entire wall can be made of insulation, as only the posts in the wall bear the structural load. Our posts are engineered "I-beams", with very thin middle sections, enabling us to cram in even more insulation ( www.jji-joists.com).

I'm delighted that Steve is building Tree House as he has an impressive 20-year track record of putting up unusual timber buildings. This includes his own house in Lewisham, south London, one of the celebrated Walter Segal designs. Segal, whom Steve got to know in the early Eighties, developed a modern approach to "post and beam" timber building that is flexible, relatively cheap and ideal for self-builders.

The Walter Segal Self-Build Trust promotes his ideas today and many attractive and award-winning schemes continue to be built using the Segal method ( www.segalselfbuild.co.uk). For information on all forms of timber construction, see Wood for Good ( www.woodforgood.com) and the UK Timber Frame Association ( www.timber-frame.org).

After building so many houses for other people, Steve is itching to build again for his own family. So if you would like to live in a famous eco-friendly corner of genteel Honor Oak, now's your chance: Steve's striking three-bedroom house is on the market through Roy Brooks (020-8299 3021) for only £285,000.

You never know, you could be Steve's very next reason to be cheerful.