01
Map the interfaces
Show where the wings meet and which valleys, walls, or gutters serve more than one roof area. Ask the assessor to identify any work that cannot be meaningfully separated at the proposed contract boundary. An administrative division between buildings may not follow the way water moves across them.
02
Set a shared sequence
Coordinate investigations, access, temporary protection, and final connections between the affected scopes. Record which contract includes each interface. If work is phased, ask how the first phase will remain complete and serviceable while later work is pending. Clear boundaries reduce the risk of leaving a junction that each contractor assumed belonged to someone else.