Photos © Craig Mackintosh
The main buildings at the PRI’s Zaytuna Farm remind me a little of those cute homes I saw in tales in children’s books as a kid. You know — the edible type, made of sugar, etc. The natural colour, texture and shape all lend themselves to this nostalgia. But, despite appearances, most of these structures are actually made of straw bale (with a daub and lime render over top), so even though they look great, I wouldn’t encourage you to try to eat them.
On my recent visit to the farm I learned that one of the walls (in a room I was staying in) was not like the others. This one, due to space constraints, had been made differently — using interwoven bamboo, instead of straw bales. I discovered this when talking with Geoff Lawton about a particular project two of the interns were working on at the time. They were adding bamboo daub walls to one of the camping platforms.
Now, I’m no natural building expert, so please don’t regard this post as an attempt to pretend otherwise. I’m just putting this short piece up in the hope it’ll get you thinking outside the box in regards to possible materials for building structures. And perhaps it’ll encourage you to send in posts on different ways you’ve built things from natural materials you’ve had at hand.
The next photo is a shot of the wall I mentioned above. If Geoff hadn’t told me, I wouldn’t have known it was different than the others.
Geoff also passed me some photographs, below, taken when this wall was being built, so you can follow along in the simple construction process. As you’ll see, it’s not complicated — one of many reasons why this technique has been used for over 6,000 years.
Further below I’ll give you the recipe Geoff gave me for the daub.
And, once again, the finished wall, with lime render on top:
Here’s Geoff’s recipe for the daub (again, this is not for eating):
- First mix on top of bamboo: Cob = 3 parts soil, 1 part river sand, 1 part bamboo leaves, 1 part water, apply by hand.
- Second mix on top of bamboo: Chaff Render = 3 parts sieved soil, I part river sand, 1 part shredded bamboo leaves, 1 part water, apply with a trowel.
- Top mix: Lime Plaster = 1 part hydrated lime paste, 2 parts white silica sand, applied with a trowel, and smooth off when half dry with a damp sponge.
- Wet wall down before each mix is applied.
Various forms of wattle and daub buildings have been built on every continent over thousands of years. Many of them have stood for centuries. Using these materials in the right way you can create fire resistant walls which will also wick water outwards, ensuring healthy dryness. Having some flex, these walls can also be much safer in quake-prone regions than concrete and brick, and, depending on how built and where placed, they can provide excellent thermal mass properties to keep your inside space warm in winter and cool in summer.
Perhaps you’ll find an application where you can make use of this simple, sustainable building practice? Grow your own buildings! It doesn’t need to cost the earth to build….
A couple of videos for good measure: