Our cats have fortunately not climbed anywhere beyond their ability to descend, and, given their weight, are unlikely so to do in the future. Big Tom has always been big and Blackie's getting fat. Last year, she was happily running over the top of the outhouses.
The magnetic catch on our cat flap no longer works, despite D's fettling efforts. Big Tom usually sits on the doormat just inside the kitchen door but Brendan has been blowing it open and it's now become too draughty, even for him. Blackie has retreated to the drawing room, to stay out of the wind.