Rake Boards can be damaged just by basic wear and tear overtime, or the shingles could be leaking causing water to get behind the Rake Boards causing them to rot.
Corner Board
Rake Board
Dormers
Fascia Board
Rake Boards need to be repaired as soon as possible because if not more water will get through and could do serious damage to the house internally. The quicker it is fixed the quicker we will be able to find the source and fix that as well.