I have a 5' extension on the back of my garage that is separating from the original building. It is 1.5" separated at the top and mostly attached at the bottom. This seems to be mainly due to poor construction - I don't see any other factors. The foundation is in good condition.
The extension is stucco and was added approximately 15 years ago. The original garage is 50 yr old redwood shiplap and currently has aluminum siding over that. (I bought a real fixer-upper!) The original structure appears to be in good condition.
What is the best way to join the extension to the original structure? I am also fixing termite and water damage to the extension, but the solid joining of the structures is my biggest concern.