Way back in April or even March 2011 I was asked whether the Westbury Community Garden, which I help out with, would be a suitable venue to build an earthbag garden seat.
What is earthbag building??
It is a construction method that is based upon materials of warfare. Sandbags and barbed wire. Very stable buildings can be produced at very low materials cost and using very easily learnt techniques. Great for places where labour is plentiful but materials are scarce.
Chris Tolley wanted to take the technique and use it for constructing garden seating, walls, or raised garden beds. He was looking for a location where an earthbag seat could be built and where people could be shown it easily. Westbury Community Garden is in the grounds of Westbury Primary School and is always looking for new and exciting projects.
An area surrounded by six raised garden beds was an ideal position. Chris designed a circular seat in two halves with seating front and back. The workshop format was to be whole weekend where participants would build one half of the seat and render it.
Unfortunately we did not get any takers in the weekend format so we revisited the concept and decided to hold a low cost one day workshop on just building the earthbag seat.
The earthbag is a continuous tube of woven polyethylene material which is usd for sandbags. Other common uses are as feedbags or rice bags.
Basically a length is cut that is longer than you need, the end is folded under and the bag is filled with dirt. Westbury Community Garden was lucky as we had a whole heap of clay dug out for an underground water tank. This was moved to near where we were building the seat. Cement was added to the clay to stabilise it.
After filling the bag it is tamped. This shapes it and firms up the earth. Before the next layer is added a strand or two of barbed wire is laid along the tamped earthbag. This is what holds the bags together along with the sheer weight of the earth.
As it is only a garden seat we did not worry about gravel in the foundation trench or wrapping the bottom two layers in building plastic as a damp proof course which is what you do when making a building.
On the day of the workshop we had a numberof people come along through the day to learn about the earthbags, how to fill them, what to fill them with and of course the tamping. Slowly the seat rose out of the ground.
At the end of the day we were about two thirds the way through the construction phase. Over the next couple of Wednesdays, when the Westbury Community Garden has their working bees it was finished, replete with a wavy top to the seat back.
The next stage is the rendering which will probably wait until slightly warmer arrives in Northern Tasmania. We will hold another day workshop in t he same format.
There has been interest from all over Tasmania in this technique.