Many hands make light earth
in Mike and the Bush Mechanics on 12 October 2011
LAST week I visited The Plummery, my friend Kat Lavers’ urban permaculture demonstration home. I’d received an email from her, addressed to undisclosed recipients, with a subject line that read, “Come and get mudddddy with me!”
That’s five d’s. That’s a lot of mud. Here’s Kat, when I arrived:
She’s re-building the shed at the back of her yard using a technique called light earth or clay light earth. The basic idea is to pack out the timber frame of a building with a mix of straw and clay.
First, you make a sloppy clay slip (a bucket of mud). Kat had gathered clods of Northcote clay from her backyard when she dug out a small pond. We carefully dissolved the lumps in water and strained it to remove the rocks.
Next, we added straw and jumbled it until the clay wouldn’t run through your fingers when you clutched a handful of the mix. Left overnight, the clay-straw blend turns malleable like putty.
As a building material, the walls provide more insulation than mud-brick, because of the air trapped in and around the straw. For the same reason, however, it offers less thermal mass – the walls themselves don’t retain warmth or coolth for as long. In this case, the method suited the location and design of the shed, which receives little sun on its northern wall and windows.
Kat had prepared some of the mix the day before, so we tried our hands at packing a wall, once she’d screwed the formwork in place. Here’s a section that Kat had completed a week earlier:
“It’s a little bit alarming when your walls start sprouting,” she said, as she pointed out the green shoots. “But I’ve been assured it’s ok.”
It’s better than ok. Solo, light earth building is slow going, but together, it’s a lark. About half a dozen friends popped in to help. When Kat explained that the method has been used for about 400 years in Europe, we all imagined the way villagers would have gathered to assemble each other’s walls. Shortly after, in another time-honoured tradition, our host cooked us a delicious lunch.
The next stage of the building will be the rendering. Kat is planning a lime, sand and clay external render, and an earth plaster on the inside. The studio won’t just be functional; it will be beautiful.
And all this got my brain sprouting. Kat had told me that in the course of her building research, she found there’s no need for a permit for structures that have less than 10 square metres of floor space.
I’ve been thinking about a recent Radio National show on tiny homes, and my rent, and about how housing is the largest expense everyone incurs. And also, about how we pay for it by exchanging so much of our time – perhaps the only thing we truly have – for money. Imagine if I could reduce my housing costs significantly, by building my own shed-home? Could I put it in someone’s backyard? (Samuel Alexander from the Simplicity Collective did that for two years.)
And, then, imagine if that little building was also a beautiful, carefully designed, demountable, light earth dwelling, with a loft for sleeping and a chair for reading? I think it’s worth my daydreams.