The next stage in the construction of our suite of deluxe chicken accommodation is to provide them with some outdoor space. The chickens have arrived, but they’re not ready yet for free-ranging as it will take them a little while to get imprinted on coop = ‘home’.
While they’re getting to know their coop, we’ve made a start on both a permanent pen surrounding the coop and on ‘tractor’ accommodation for putting them to work round the quinta.
I’ve been studying many chicken tractor designs over the last while, looking for something that’s light enough for single-handed moving, but is still large enough to provide the chickens with enough scratching and foraging space that it won’t require re-siting every couple of days. Since they have a permanent coop, the design doesn’t need to incorporate secure night-time accommodation. I kept coming back to the idea of a geodesic dome, encouraged by the success Milkwood Farm in Australia has had using this idea.
But once I started studying the detailed construction plans of their dome, I started to lose enthusiasm. The measuring looked complex and the black pipe I was planning to use doesn’t lend itself to being clearly marked, let alone colour-coded. When I got to ‘special blue solvent glue’ I ground to a halt entirely, having never seen the like in the local hardware stores. So it seemed to me that the traditional Buckminster Fuller-design 2-frequency (2V) geodesic dome was a lot simpler and easier to construct.
I inherited a fair amount of half inch irrigation pipe (16mm LDPE dripline) with this quinta, none of it actively in use at the time or since, a lot of it in fairly short sections, and some of it slashed by passing brushcutters where it had been hidden and half buried in undergrowth. Constructing a geodesic dome out of the shorter and damaged lengths seemed an ideal use for what might otherwise sit around gathering dust until I found another use for it. I wasn’t sure though whether it would be rigid enough to make a successful dome framework, so along with the nuts and bolts and chicken wire covering I needed, I bought some heavy-duty galvanised steel wire for reinforcement. (This, in any case, is needed to replace the vine trellises.) To begin with though, I decided to see whether the pipe on its own was up to the job.
The structure I decided on is a 2V geodesic dome. Thanks to one of several online geodesic dome calculators, it’s very simple to work out exactly what materials are needed for any given radius of dome, what lengths to cut the struts to, and how to assemble the framework once the struts are made.
I based the structure on dimensions for a 1.8m radius dome, but shortened each strut by 1.5cm at each end to allow for flattening and drilling the irrigation pipe to bolt it together, effectively reducing the radius to 1.7m. The dome is assembled as 6 pentagons, 5 for the circumference and one for the top, then joined together as shown in this series of images.
But this was as good as it got. As soon as I tried to move it, the whole thing collapsed on itself again. Not only did the galvanised wire not help, but it made the situation worse as once the struts bent over, the wire (which had bent with them) tended to keep them that way.
There was, however, a big bonus from this stunning failure to accurately estimate the limitations of my construction materials. Seeing the completed 3.4m diameter dome immediately made me realise that a framework of this size (constructed from more robust materials, obviously) could be a very useful and versatile resource: covered in polyethylene sheeting, a Spring greenhouse; covered in fabric and canvas, summer visitor accommodation …
But back to the drawing board … I looked at the Robert Freeman design on Milkwood’s blog again and gave it some more serious consideration, but somehow I didn’t feel ready to give up on the original geodesic dome just yet. The dome I’d started with was pretty large. Too large. Not only for the frame it was made from, but for ease of moving and potential siting too. I decided to try a cut down version and reduced it to 60% of its original size, minus the galvanised wire. I also noticed that it was better if I didn’t do the nuts and bolts up so tightly – a partially deformed tube has more rigidity than a completely flattened one.
Night and day! This worked a treat. The resulting structure has integrity. It can be lifted with one hand, is flexible enough to be squeezed through tight spaces, but immediately regains its shape. It will need re-siting more frequently, but it will go anywhere on the quinta.
The rim can be pegged down for security and there is a 40cm skirt of chicken wire beyond the perimeter which can be weighed down with rocks or planks to deter diggers – whether hens from the inside or other animals from the outside. The door is sited above ground level and it’s easy enough for a me-sized person to climb in.
Next stage is to see whether the chickens take well to it …