I’ll post more on the discussion forum.
A poorly installed two-ply rim beam was coming apart. It was done such that water would drain between two decking boards and straight down between the plies. Resulting swelling and warping literally tore the outer ply off.
When I removed the outer ply the inner ply had a carpenter ant infestation, so it’s all got to go.
The original 2-ply 2X10 beam does not meet IRC2018 (our current Code) standards. I plan to improve the situation, so this doesn’t happen again. Am I required to install something that meets IRC2018 as replacement?