Cover Enquiry and Progress Report

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 Cover Enquiry

Have discussed requirements with Polytunnels covering company located in County Cork. Recommended use of very strong UV proof Tape to join polythene triangles, just shy of 2 inches wide and 20 € per metre. This method is likely to be much stronger, faster and reproducible than the plastic welding method I had im mind up to this point, but Liam from Allens, Allenbridge advised that the tape is stronger than the polythene itself.

So , how many joints are there.

165 sticks in construction

So for this 5.2m diameter dome what does the cumulative lengths of the sticks come out as?

Well using the calculator supplied by buildwithhubs.co.uk (download excel file from company)


The number of sticks for a 5.2m diameter gedome and lengths is as follows....
  • A   sticks (short)   81.9cm     quantity 30
  • B   sticks (med)    96.2cm     quantity 55
  • C   sticks (long)    98.4cm     quantity 80
However there is a further 4.4cm distance from the end of the stick to the centre of each connecting hub which needs to be accounted for and therefore the revised lengths adding 2 x 4.4cm are shown below the following diagram.

Extra distance from end of stick to hub centre needs to be accomodated.


  • A   sticks (short)   90.7cm     quantity 30    = 27.2m
  • B   sticks (med)    105.0cm     quantity 55  = 57.75m
  • C   sticks (long)    107.2cm     quantity 80 = 85.6m
A total of 170.55 metres   (There are 18 sticks that form the base at ground level (9Bs and 9Cs) which do not require taping...however this may be advisable offering extra strength to the material where it is tethered to the ground/structure. (still to be decided). Therefore I have left these sticks in as part of the cost breakdown. This means 9 rolls of 20 metres length tape at 20€ pre roll = 180€

Triangle Cut Trial

As another sanity check I took the A & B triangle from above and used an old roll of laminate underlay to cut out a couple of triangles to ensure calculations are approx correct.



Its not bad...and certainly on the right track....but depending on stretchability of the actual film itself a little more leeway may be required. This probably due to the errors associated with the slight extras due to the width of the bamboo sticks themselves. ie typically 1.8cm or so in the above  but wider on bigger sticks..... would add an extra little bit to get the perfect fit. An average figure will be required to increase the size slightly...but this will result in some tigthness and looseness in different regions as the dome is taken down and re-erected elsewhere. If I chose the correct number this is not anticipated to be a big problem and ids dependent on the properties of the polythene which I do not as yet possess.

As a quick aside , I am contemplating making one or more of the roof, lateral pentagons using an optically clear plastic and perhaps making them removable. This would help greatly in making the dome more visually appealing from the inside and also allow fresh air to circulate when the weather is appropriate thru temporary window detachment. 

Progress Update

I am up to 66 sticks fully formed out of the 165 or so required. (a few spares foreseen). I have concentrated on the narrower bamboo poles to form the shorter triangle sides associated with the 5 pentagons in the structure. Rightly or wrongly I am assuming that the styructural requirements of these will be lower than that of the longer triangle sides associated with the base and heaxgons of the geodome. 
A consequenece of working from narrow to wider diameters is that I am in need of a larger diameter dowel to process the larger sticks. Production has therefore slowed down and will slowly grind to a halt until the new dowels are delivered....hopefully 7 covid19 days away.

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