Flashing failure at chimneys and valleys
Why it happens here
Freeze-thaw cycles from December through March work the sealant loose at every penetration. Water gets behind the flashing, and the leak shows up on the ceiling far from the actual entry point.
Our approach
We reseal chimney and valley flashing with fresh caulking, replace any corroded metal, and test the repair with water before we leave. On replacements, we install new flashing rather than reusing the old.