Q: Our 21-year-old house has its original roof. We've been fortunate not to have experienced any leaks except one time years ago after a very windy rainstorm. A local roofer repaired the problem at ...

Q. Our house faces north and south. On the north side near the middle to the east corner of the roof the shingles are turning black - in streaks and a small amount of mold has started to grow on them.

Q. I have a white asphalt roof about eight years old. It has developed long vertical streaks on the north side. It looks like some kind of mold. I blamed the large, old black cherry tree on that side.