This isn't damage caused by me, but as a result of the addition. I knew there was some damage, but the extent surprised me..
The left picture shows the rotten header on the south side. It consisted of two 2" x 8" boards nailed together with 1" spacers. What you see is the outside board almost completely rotted away. The damage was caused (I think) by a combination of water damage and termites. There was not proper drainage around the chimney, and the water soaked into the roof. This made the wood in the area very attractive to termites. They ate well! The right picture is the damage to the roof boards themselves. I ended up taking up three boards deep on this side of the house, and five on the east side (about 100 sq. ft. total).
The left shows a very consumed rafter on the east side (the side adjacent to the chimney). Obviously this one needed replacing. The right picture shows the rafters on the south side after I've taken up the roof boards. More rotten rafters that had to be replaced, but the would have needed to be replaced anyway (even without the rotten wood), since they were cut to accomodate the chimney.
Another shot of the south roof. I've cut the rotten section out of one of the rafters in this picture. The left shows a section under the roof right near the corner. I don't know what emerged from these old larvae sacs, but I'm sure they were up to no good!
Ready to reconstruct..