Build a Geodome from some bamboo sticks and plastic hubs during a pandemic? There are many pros and cons but in the end I hope to have a lot of satisfaction at having completed a greenhouse, outdoor socialising area and a bit of a challenge.
A bad day for the dome. I watched from the safety of the house to see the dome initially handle the buffetting of the high winds but eventually succumb to the forces of nature.
Initial weathering of Storm Barra
Eventually succumbing to extereme buffeting
The storm was intense and ongoing for many hours on that fateful day. For many many hours the wind strengthened and waned changing direction as the storm passed over Ireland. The shelter from the surrounding buildings , trees and hedges protected the dome from the worst of the gusts of wind but at certain orientations the protection is very limited.
It is difficult to know what the point of failure was.... During the storm it was unsafe to investigate , my sole activity being to dismantle / flatten the geodome remnants as portrayed above to try and prevent further damage and material flying away. However, it was clear that the frame had not broken as such....ie no bamboo sticks had fractured ...rather the connecting hubs had given way under the repeated flexing of the joints from the buffetting wind.
Dislodged Hub Connections but no Bamboo breakages / failures
The metal 90 degree brackets used to attach the bamboo frame to the circular pattern of concrete blocks were deformed due to the forces involved ...and this may well be the source of the first catastrophic failure. Indeed from the video of the just collapsed dome you can see that the face nearest the camera, the location where the above bracket was situated.
It is also likely that one of the hubs loosened and the 'dome' shape was lost creating a large sail - like sheet of polythene to capture more energy from successive gusts of wind to repeat the process. 2 or 3 of the hubs were found to be completely opened up ...the following day....so maybe a tighter hub...would/could have prevented the collapse.
What Now?
I have recovered all of the frame elements and cleaned them up of all the mud and rinsed with a dilute bleach solution in order to remove any ongoing micro biological attack over the winter months.
Most of the 'bamboo' is in great shape though there may be more lengthwise splits than was observed during the first embodiment of the structure. (hard to tell) . I had a little spare so should be able to rebuild the frame completely with no more cost. The polythene cover ended up woth some local damage that has still to be fully assessed. It only ripped to a degree in a small area though a tape seam or two may have given up the ghost. Again, I have ample polythene and tape to repair whatever may be revealed when fully unravlled on a warm windless spring day in a few weeks time.
Dome II will therefore be different in 3 ways...
1) I will replace the small through bolts used to attach the polythene cover to the frame with quick release poppers. (if a big storm is forecast...I'll remove the cover and recover on storm passing)
2) Metal bracket strength will be increased to try and avert potential buckling leading to subsequent hub loosening.
3) A slight increase in ventillation holes will be made to try and lower humidity levels slightly through greater airflow through the structure.
The completed structure So.....In the words of Talking Heads....How did I get here. From earlier posts you will have seen the assembly of the polythene cover unit cells of Hexagons, Pentagons and 1/2 Hexagons......that allow the build to be easier to visualise and ultimately build correctly. Using the UV resistant mega strong tape and the gadget below (see earlier post) start connecting the unit cells into bigger fragments. (the gadget will take the strain of when trying to form a 3D structure from flat sheets). Its easy to get lost so I'd recommend joining 5 pairs of 2 hexagon cells as the basic 5 vertical stripes that you have to joing together via intervening pentagons. The repetition of this operation will hopefully result in less (0 errors) Gadget developed to join flat sheets to form a 3D cell. Once the whole structure is completed ....wait for a dry, windless day and go for it. I was assisted by my daughter who kept tension on 2 ropes straddling the top of the geodome whi
Progress has been slow but steady off-late thanks to non-deliveries of dowels from the UK (brexit) and a certain lack of focus from pandemic blues, for want of a better term. However, the current status is All sticks or struts manufactured. Polythene unit cells being assembled Site has been attacked with weedkiller and soil turned. Concrete blocks sourced. Numerous seeds are being cultivated in trays. Polythene Cover Cells So....after a couple of previous trials working with the original 'triangle' base units I quickly realised I could save a lot of time / effort and tape by making larger base cells. Whilst in theory it is possible to construct single cells from the core haxagons and pentagons I decided to use 1/2 heaxagon units due to difficulties in handling, lousy weather outside and therefore strict limitations on indoor area available to stretch out polythene film. The core thing about the hexagon patterns is that they are not real pentagons due to the raised centre (3D
Its been a few months since the completion of the Bamboo framed Polythene Skinned Geodome was constructed and I wanted to summarise how things went during the first season. Setup - Watering was supplied by an external tap / hose / battery operated timer and distribution kit as described below. Tuning in the amount of time the water was switched on, number of times per day, the size and drainage of each plant pot led to some plants being overwatered. After adjusting the sequenece over time the system worked very well ...even during the extended periods of absence from the house,dome. Environment Once the water was sorted the other big variablke is temperature. During sunny days the inside of the Geodome rose to the high 30's such that any work to be performed inside became almost impossible. (think Sauna!) During overcast / windy days the dome sat around the mid 20's and probably got no lower than 18 degrees or so during the Spring, Summer nights. Excellent growth conditions fo
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