Silicone was also injected on the inside between the risers and the metal cladding to cover the spaces between adjacent screw bolts and to form a seal between the wood and the sheeting. This was probably not essential for the purpose of waterproofing because of the overlap of the sheets and the caulking on the outside but it was thought it might deter movement or vibration between the sheets especially during the rotation of the dome.
The brown stuff showing besides the ribs is the silicone I was using at the time. I have no idea what I had originally bought the stuff for and I would have preferred black but why waste :). Anyway the inside would be painted over with several layers of matt black and so I was not worried it might show. I did clean up the excess splatter though before I got to painting it ;).
