My first growdome
Firstly I laid out the struts in the pattern they would be constructed, six on the outside with two laid towards the centre at each joint. I had graded the struts so the least straight ones would form the base, reasonably thick hazel would form the sides of the icosahedron and the lightest, straightest hazel would form the roof struts.
For this basic ‘wild’ dome construction I used a very simple method of drilling holes and
connecting the struts with wire and rope. In order to stop the ends of my hazel from splitting, I lined each hole with a bit of used copper pipe.
I connected the holes on the base using fencing wire pushed through and bent over to hold the hazel secure but still allow movement. Then starting at one ‘corner’, I lifted the two sticks that would form a down-pointing equilateral triangle and used 2 foot lengths of high-tensile plastic rope to attach the top side of the triangle.
The reason I used rope rather than wire for these is I attached three ends together, untied to add a fourth and than later, once the sides were complete, untied again to add the roof strut to each vertex. I used reef knots to secure the vertices (right over left & under (thumb knot) then left over right and under).
This is where things got a little problematic. Once I had one side ‘up’ (always keeping an eye on the model) and moved onto the next, the opposite side of the ‘cylinder’ would collapse onto the ground and pull the structure down.
One problem with geodesics is that they do not become a self-supporting structure until they are complete. I might have wished for some assistance here and muttered quietly to myself about my partner Sarah always being out, but resolved the problem by staking the poles down with string, like with tent poles. This allowed me to hold up the structure while it was still flimsy due to lacking the top of the icosahedron.
I then tightened-up the joints on the base to restrict their movement. I laid out the roof struts, the hazel rods tapering towards the middle, and connected them at the centre, passing the rope through all five holes of the top vertex, leaving a bit of play.
I moved the top to the centre of the cylinder and set it up in a tipi shape. I untied each top vertex, re-threading the rope in some instances to allow for ‘settling’ of the wild wood, then attached the top struts. I supported the roof with a large stick for the last two struts. Six more reef knots and the basic structure was complete.
I included a central pole to add stability to the structure, slightly lifting the roof which tightened the dome up. I took another photo of my ‘greenhouse’ and published it on Facebook where my family could take the micky out of me for building a greenhouse with no glass.