Sunday, 1 February 2015


When it rains, the green roof acts like a sponge, soaking up the moisture. Excellent for reducing runoff in urban areas! It should be much more widely-used.

After rain, the water drains off the roof for a period of days, dripping relentlessly. I was gutterless for several weeks, and there was something wretched about working in a building that was dripping constantly along it's front edge with a muddy strip outside the door.

I didn't want to put any more plastic into the building. It took a lot of research, but I found an aluminium gutter manufacturer.

It's beautifully made, but it's not snap-together kit - you have to pop-rivet some overlap strips onto each joint with silicone bedding. 

The downspout will go into a 1000 litre tank. There will be a picture when it does.

Building Costs

The budget was to spend £10,000 + VAT on this building. This is how it turned out:

Building Costs (Excluding electrics & internal fittings)
Heavy Materials: Bricks, Sand, Gravel Clay
Roof and Substrate: Pond liner, Coir, Perlite, Leca, Shells
Timber, OSB
Lime Putty, Hydraulic Lime
Equipment Hire & Van Hire (for scaffolding)
Tools & Equipment, inc. forced action mixer
Protective clothing
Ironmongery: screws, nails, builders strap,
Tarps, and wood for shelter dome
Insulation. Recycled Foamglass gravel & blocks, sheepwool insulation
Misc., mostly glazing and skylight
Contractors: Groundworks, limecrete slab
Total, Net

The van hire was to fetch and return the scaffolding from a friend in Suffolk. If you have to pay for the scaffolding, you might need to add £1000 or more for this. I expect to spend around £500 on electrical fittings

There isn't much wood going to waste: I've one sheet of OSB, lots of small off-cuts for the woodstove, too small to be of any value; a few lengths of 2 x 3. And a dome framework, now uncovered, currently functioning as a garden sculpture.

I hope to be able to sell the mixer when I am finished with it. Who knows, perhaps the dome too. As I have said previously, it would have been a good idea to spend a little more money on the crucial tarp that went over the dome to keep the straw dry.

If you are building a house - to live in - I think there is a way you can register as a self-building business, and reclaim the VAT on your inputs.