I first encountered the tree that was to become our inspiration on 20 September, 2002. Exactly two years later, foreman Steve Archbutt arrived on our patch of Clapham wilderness to turn our dreams into reality. The design process had taken longer than anticipated, in part because we faced a constrained site, but mainly because we had serious ambitions: our specification was for a house as beautiful and sustainable as the tree it would rise to embrace. Happily, Peter Smithdale of Constructive Individuals met this challenge with enthusiasm and imagination.
Cutting back, digging, levelling and shifting muck: it didn't take long to turn our verdant plot into a bleak expanse of mud. This was not a very ecological first step, but the habitats of tree, pond, wildlife garden and house will give our 180sq m even greater biodiversity than it started with.
Before we even had a slab to build on, we were installing some serious eco-kit: 200m of pipe in four 25m boreholes through which a refrigerant will flow, extracting heat from the ground to warm the house in winter.
The site demanded serious foundations: a concrete slab on 9m piles. Although we didn't welcome the concrete truck to our site with open arms, we knew this was the only way to ensure the house would endure, perhaps the single most important criterion of sustainable design.
The slab was not the end of the concrete story. A retaining wall had to be constructed to stop the neighbours sliding into us, and our house-wide pond had to be stitched into the slab. This is the most over-engineered frog-house in London - it took weeks to complete. It will be worth it though, helping us to keep cool in the hot summer months to come.
In the snowy heart of winter, building did not feel like the best of career options. Nonetheless, site stalwarts Steve and George pressed on, digging our drains and connecting to the sewer. We decided that the most ecological way to deal with this aspect of our waste production was to export it in the usual manner, albeit dispatched with the most water-efficient toilets on the market and with a compost heap handy for occasional liquid relief.
Our timber frame got lost in the post in March, so we occupied ourselves building garden walls and fences. The walls at the front were built with reclaimed bricks and lime render, minimising the effects of manufacture and ensuring the walls retain a flexibility that will help them to survive if the earth moves beneath them. Meanwhile, metal designer Jonnie Rowlandson got carried away making us a fiery fence out of scrap steel, copper and bronze.
Six months in, we penetrated the third dimension. Our timber frame, made from light-weight, high performance 'I-beams', had to be cut to size on site, but Steve and George were happy to be breathing sawdust at last.
Having got into top gear, we had to shift rapidly back to second when the crucial bit of steel to hold up the back of the house got made wrong (twice). The front of the house rose as far as it could, but it felt like we were paying a penalty for this un-eco component in our otherwise sustainable structure: the frame components all came with Forest Stewardship Council (FSC) certification. Eventually the steel arrived and the pace picked up once again, as did cheerfulness both on and off the site.
After years of planning, the emergence of rooms, or at least room-like spaces, was exciting. With no sheathing on the stud walls we could still see through the building, but we got our first sense of how far and wide we will be able to swing our four cats. In fact, we have kept interior walls to a minimum, creating large spaces that will be flexible enough to satisfy the needs of the inhabitants of the house over its long life without too much hacking about.
With the installation of our triple-glazed windows and external wall sheathing, it seemed feasible for the first time that this entertaining but challenging hobby might result in a space where Ford and I could actually live. Our well-insulated building envelope will help to ensure that our experience here will not only be very comfortable but also carbon-free.
Our roof was delayed (surprise!) but when it did finally go up we were suitably gob-smacked. Our team of joiners - Steve, Mark, George and Pete - turned a pile of FSC douglas fir into beautiful branching trusses to hold up the roof and our solar power station. The roof was difficult to engineer because it is almost entirely pitched one way - south - but we will be rewarded in years to come with an abundance of hot water and cool electricity.
SEPTEMBER - NOVEMBER
There is still rather a lot to do, but once the house is weather-tight the pace should quicken. In theory. Watch this space for more eco-building tales in the months to come. For more information on the project, check out www.treehouseclapham.org.uk.