Originally Posted by Icefishww
F/C meant fiber cement and it is the horizontal lap siding 7-1/4" variety. There was step flashing before and a trim board that covered the vertical leg but the caulking came apart and in addition the T1-11 was never maintained. It's old but overall in good shape so I'm thinking I'll just replace the bad cut outs with OSB and side over it. I wanted to make sure I don't screw up on the flashing because I'm somewhat new to this,
Daah..sorry for the brain fart. I'm so used to generically referrring to this as "Hardi siding" , that "fiber cement" just did not trigger any brain activity.
I'd cover the T-111 with felt or Tyvek before installing the fc, be sure to leave the recommended gaps at seams and corner boards, install felt splines under the butt seams, and use a high quality sealant, not just regular latex painter's caulk. We use an acrylic urethane manufactured by SiroFlex; this is the same stuff used to install vinyl replacement windows, and is some tough.
Your note that the "caulking came apart" is exactly why you must flash for waterproofing, not caulk. Caulking is a temporary solution to a permanent problem.