Originally we had planned to do a smooth dome on the round room, a bit like the moorish domes you see throughout this area. But when we looked into the safe construction of these we came across geodesic domes, which are easy to construct and very, very strong. So, we've decided to do a modern take on those domes of old!
The main structure is made up of triangles of wood (same wood as the ceiling planks) in three different sizes. These are held together by metal tubes and strapping. The inside covering will be cane, topped with some sort of cork-crete to provide the insulation. The final waterproofing we're still deciding upon, but somehow I'd like to incorporate a mosaic of tiles into it.
The south side of the dome will have two or three triangular windows to bring light (and heat) into the mezzanine level. The north, east and west will have one triangular window each.
Joining a rectangular roof to a round dome has exercised our brains a tad. It's also developed Dave's carpentry skills. He first had to do the joining of front face beams at the entrance to the round room. Then at last he tried out the triangles of the geodesic structure.
Unfortunately, in October 2011, whilst trimming the wood down to equal widths, Dave had an accident with the bench saw....he still has his fingers, but they took a while to mend...and bend again. It was about 5 months before we started work on the dome again.
Spring 2012 saw us back at it. And the dome structure was quickly finished. Then to caning it.
IOn top of the cane we put a thin layer of papiermache which we borax against bugs. Then a thick (15cm-ish) layer of padobe (mud, cork bits and shredded paper) on the bottom section covered with a 2cm layer of papercrete (sand, shredded paper, cement) to weatherproof.
To lighten the load higher up the dome we're using sacks filled with cork bits held in place with chicken wire. This is covered with the papercrete. Check out this site to see some amazing things made from papercrete.