Not only is it heavily covered with moss, but the roofing material is so deteriorated and brittle that it is breaking apart.
This roof was let go for so long that now significant work will have to be done elsewhere at the home: sheathing and rafters below are decaying at this point. When a roof goes, it goes fast in the wet climate here in Whatcom County.
Steven L. Smith
Bellingham WA Home Inspections