For what it's worth, on the bottom of the 2X8 rafters are some 2X4's nailed to keep the 2X8's from twisting?? I guess that's why there are there. They are on 8' centers, the highest one is just over 10' off the ground. Was thinking of trying to prop up a few of the 2X8's using the 2X4's as stops to hold the top of the prop and just wedging the other end into the ground. The 2X8's are supported at one end by the building and at the other by some 4X4 posts with two 2X8's bolted together running between them. Seems stout. The 2X4's under the tin are worrying me.
So, what do I do? And, what do I replace the nails with?