I am planning on building a geodesic dome for a workshop and have some questions of a technical nature that I hope you can, at very least, help me find where I can answer my questions. I will start off with a full description of the short history of my ideas thus far then a listing of technical specifications. I started off seeing an ad on Facebook for a company that makes sets of hub joints to make pvc pipe into a geodesic dome strut system. After deliberation and discussion with a company rep I was planning on building a frequency 3, 5/8 dome very close to 19' in diameter. In case you don't know, the frequency of a geodesic dome is the number of line segments between the 5 arm hubs basically describing the complexity of the dome. The 5/8 is because odd numbered frequency domes cant be divided in half evenly so you either get just short of a hemisphere or just over. I imagine you already knew that but just in case not it is easier to describe it now. Any way, in my search to reduce costs I started to look for other places to source hubs cheaper as that was my largest single expense. I did find another company selling another style of hub even cheaper that was impressive but I wasn't sure if it would really work well with other ideas I had for it and I still wasn't to sure about using pvc for something I intended to be semi-permanant not mention the fire and hot stuff. So, in my searches I found an alternate construction method called stressed skin. I really liked the idea of making the entire dome from sheet metal triangles riveted together especially since I was already planning on using a thin metal paneling to cover the pvc structure. However, this type of dome is rather difficult to find info about. I imagine because of it's technical nature and lack of companies distributing kits like the hub system kits and this brings me to my questions.
First, I will give you a basic list of some of the details of the dome, of what, and how it will be built. I am still going to give the dome a 19' diameter but that might grow a little as my material utilization calculations become more accurate. As I said this will be a frequency three 5/8 dome (also seen it called a 5/9 dome which I think makes more sense) which means it will be made up of 105 triangular panels minus 6 removed for the doorway so 99 and 4 slim partials around the door. These triangles are made from 3 different line segments. One triangle has 2 legs made of the longest line at approximately 47" and the third is the medium line of approximately 46". The other triangle shares the medium length line and the other 2 legs are the shortest line at approximately 39 3/4". 69 of the big triangles and 30 of the small ones in total. This brings me to my first and most important question. What thickness material do I use? I have gotten an opinion or two and it seems 20 gauge galvanized steel would be both strong enough to hold snow and cost effective. This is what I am hoping you can confirm. Also it has been recommended to me by the gentleman who built the dome I am basing this on that I press in a design into the surface of the panels or in some other way reinforce them so as to help control flexure. Do you think this is necessary? Next, I am planning on assembling these pieces with pop rivets. Probably 3/16" in diameter and made of steel probably between 10-12 per seam of which there will be 3 per joint, one for the flange on the triangles themselves and another two rows on a strip covering the joint. Does this sound sufficient to you? Could aluminum be a strong enough rivet for my situation do you think? The final point and one I have the least questions about is the doorway. Since the skin is the stressed component I am aware that my door frame will have to be structurally sound so I am going to fabricate a frame out of a sheet of 11 gauge cor-10 where the sides will basically be I beams welded together with top and bottom similar. Of course i will rivet this to the dome or more like rivet the dome to this as I plan on this being a free standing piece supporting it's own weight.
First time posting here and hoping to find a little reassurance that this will work as I am extremely excited at the prospect of having my own smithy. Thank you for your time.