A tree bog is essentially a small shed raised over a hole with trees around. The trees eat the ‘humanure’, so it is a very ecological solution. Our tree bog is mounted on a frame and keyed into flat stones. It is on agricultural land so we couldn’t use any concrete or anything that might be considered to be a permanent structure. The walls are made of rough cut chestnut slats. The chestnut is local and very cheap. Every other slat goes to the ground for sturdiness and the sides of the hole below floor level are filled with straw. The side planks of the floor are removable, as are the front steps, so that the straw can be replaced as necessary. The roof is made of corrugated polyester – not the best option, but one of the most cost effective.
It is not quite a metre from the floor to the ground beneath the hole. We looked at many designs and everyone said it must be a metre, but we couldn’t find any explanation as to why! it just seemed to be something that was said and repeated. We needed to ensure that the structure was secure, so we worked out our own designs and construction. We’ll see how it works out! (UPDATE: five years on and it’s still working brilliantly. No pests and no mess or smell. We’ve only had to empty it twice and that provided a good helping of compost for the garden.)
The bench has a proper toilet seat and compartments either side for loo paper and sawdust. We find some sawdust works well as we use it in our composting toilet in the cabin. We’re oiling all the wood with raw linseed oil, which is a good and environmentally sound solution, especially for exterior wood. It dries relatively slowly, but only takes a couple of days in the heat. It’s a bit yellow at first, but that seems to fade. We won’t do the interior this summer, but will probably do it before winter.
We haven’t planted all the trees and shrubs around yet, but there are substantial woods behind the tree bog and we have transferred some local willows an bamboo. There are young oaks growing around too. The local farmer can’t understand why we insist on allowing the trees to grow in the fields. He wants to cut them all down and keep open fields of grass, which he says is to prevent fires! We think keeping the trees is more useful in preventing fires, but we are newcomers here.