Like several houses in the neighbourhood ours has gutters from the dormers running backwards and then a downpipe just to the roof so as to let the water drain down and across the roof to the gutters at the lower edge.
The home inspector said a downpipe should be added to run down across this span so that the water runs through it and not over the shingles.
Right now the problem seems to be a discolouration extra fungus-type buildup on the water track.
Can this perpetural stream across the duroid-type shingles be damaging or shorten their life, or is it just more unsightly? I've heard it is just an aesthetic issue.