Building a DIY greenhouse

My first growdome

Laying out the greenhouse structure

Laying out the greenhouse structure

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

copper pipe lining strut holes

copper pipe lining strut holes

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 greenhouse dome base

The greenhouse dome base

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.

The icosahedron greenhouse frame

The icosahedron greenhouse frame

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.

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2 Responses to Building a DIY greenhouse

  1. Kole says:

    Loving the domes, looking forward to reading the book, trying to build my own but i’m struggling with the polythene. I’ve been looking at the polythene sites to find your “3 x 7.3x 1m Sunmaster Tunnel Covers”. But I can only find selling by the metre, I haven’t found a tunnel cover anywhere. Would you be able to provide any more details please as I really want one fo these on my allotment. K

  2. "Kirpi" (Carl Duffin) says:

    Hi – I just spent the best part of this weekend just gone, building one of those aluminium and polycarbonate greenhouses because I was going through two sentry box style plastic greenhouse tents every two years and this was a compromise between building a greenhouse myself and getting around the glass problem which my good wife was not comfortable about.
    14 hours (no kidding) of plans that make no sense and finding that two pages on, having got a 3-dimensional bracket just right, I have to back off all screws to be able to slide in two more slider bolts that were not mentioned two pages ago! The most depressing, frustrating weekend for some time!
    But it is up now and I will hopefully lessen my use of plastics and landfill for a few years.
    If it were down to me and next time I will – make the next one out of timber framing and possibly polycarbonate glazing.

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