Catsle as of October 19th, 2018
More images, build and otherwise, in my catsle album
After its first cold winter, I learned that the catsle could use more insulation, and that the tower lids weren't quite waterproof.
To try to solve this, I created crenelated "hats" for the towers that provided both an insulated layer underneath them to keep more heat in the structure, and directed all rain and snowmelt down past the tops of the tower, as a good roof should, by extending the bottom edges of the hats well past the original tower surfaces.
This new arrangement has been through several heavy rains with no leaking at all, and although it has yet to see a winter at this point, I expect it to do better with regard to snow. The new insulation (1" of insulating foam board, about R-4) under the caps should help prevent snowmelt on the tops of the towers due to the interior of the catsle being heated.
In addition, I built a 2-part roof system for the barbican, as snowmelt from the main roof was creating significant amounts of ice at the bottom floor cat door. The new roof should cause the snowmelt to run to the sides before it refreezes. Next summer, I'll go in and insulate the roof itself. One project at a time!