You will need to go at least 4ft up with your reinforcement and a 2ft appron.
A roll that is 4ft × 25ft
2.5 lenths for the 9ft ends 3.25 lenths for 2 13ft sides. You will need 12 lenths of 6ft long 4ft wide.
72ft
3 rolls of 25ft.
If you plan on completly cover the run.
2+6+8+6+2 = 24ft
2 ft apron 6 ft up the wall 8 ft across the top 6 ft down the wall 2ft apron on the other side. That's the length you need for one section.
Oh and a tip for working with HWC. Band aides lots of band aides. That stuff will eat you up...