I just had my shingle roof redone. This included a complete tear-off and replacing all the old rotten sheeting and facia boards along my open eaves, covering the entire roof with a 2nd layer of OSB, and applying bituthane along the drip edges and valleys.
The tear-off revealed that the shingle had been put over the original 40yr old hot-mop. Since it leaked, I knew there would be wood damage, and most of the rotten areas were caused by water intrusion at rooftop or drip edge flashings. All of the drip edge plywood had de-laminated. In several places the 2x10 fascia was fine along the bottom edge but rotten up under the edge flashing. I also saw that latex paint on the fascia could act as a 'container' to keep moisture in the wood from escaping.
I am now prepping the eaves and facia for repainting which includes some stucco patching and old wood repair. My question is should I use caulk to seal every crack and crevice (where rafters meet the facia, sheeting and blocking) under the eaves or is it better to just paint the wood and leave these wood joints unsealed so the house can breathe and dry out?