Staining on Roof sheathing???

Any idea on what this might be? These pictures were taken today on a Town Home inspection (house is 27 years old).

Any help would be appreciated.







Hy Kevin I had one almost identical to this and had trouble figuring out what could have caused it .30 year old home
Finally found a plumbing stack down at the edge just under the insulation .
Never could figure why the stains stopped just like yours at the edge of the plywood.
Maybe better glue on the plywood ( just guessing at this time ) 3 years ago for mine .
Roy Cooke

Kevin, the staining on the sides of the truss top chords and running onto sheets ajacent to the fairly uniformly dark brown sheets make it look like moisture intrusion of the roof membrane.
It’s strange that there is a dark sheet near the peak of the roof and another near the base. Thsy look like separate areas with similar conditions.
Roy has a good point… are there plumbing stacks above these areas?

Some of the clues from the pics don’t make complete sense, and ya really need to be up close and personal. But there appears to also be water stains on some of the framing members. What about also considering possible roof leaks that caused sheathing damage, and only some of the sheathing was replaced at some point in the past?