The grain bin dome roof is like a pizza. The slices are bolted together similar to standing seam metal roofing.
The bolts coming down through the seams are long. There are nuts tightening the overlapping ridges together, but a good inch of threaded bolt sticks down below each nut.
I cut 12" lengths of metal hanger tape and used additional nuts to secure a piece of hanger tape to each bolt.
I bought 2x2 boards and used them to make "rafters". I bent the hanger tape down to wrap around the 2x2 and screwed each end of the tape.
In the east bin I cut blocks from scrap pieces of rigid insulation and used them like spacers to allow more space for insulation.
In the beginning, I went overboard with insulation. Eventually, I realized that spray foam does not need to be so thick to be effective. On the west bin I did not add spacers.
In the first bin, I used scraps of OSB and plywood to make the ceiling. Starting at the outer edge I screwed the ceiling to the rafters and then filled the space between wood ceiling and metal roof with spray foam. As it cured, I added additional rows of ceiling and then more foam until I got up to the center of the roof.
By the second bin I knew I the spray foam would stick to the metal roof if I starting with thin layers and built up after it cured.
I found these used turbines on Craigslist and put them on each dome cap. I thought they would pull heat out of the bins, but they were not effective. I later replaced them with electric attic fans.
Most of the upstairs isn't very pretty yet. I'm still in the mode of getting to the point of safe and functional and then moving on to the next pressing task. I have not done much finish work yet.
Thanks again for your attention. Next time I will explain how I close off the center caps for the winter.