So it has come up several times that there is a construction issue with putting an octagonal roof on a round water tank. As Dave Taylor has pointed out to me on a couple of occasions, and I think Jon also, that with the design there are gaps at the peaks where the roof panels join and the tank rim. Its a matter of geometry. The tank touches the roof panels only at the center of each flat panel.
My question is how was this dealt with in the real world. I assume I already know the answer, and that answer is that the roof panels sit on rafters where the panels join. So while I get how it is constructed and fastened down, the fact remains that there will still be gaps now between the center of the flat panels and the rafters.
What did they do about the gaps? My assumption is that they left them, or at the very most screened them. Tanks do need ventilation to keep them from imploding. So this would form a natural vent. But I would like to know if anyone knows. As a water guy it is interesting to me. I am only familiar with concrete and steel. I have never had the opportunity to examine a wood tank.