I'll split this post off because I'm bragging feeling relieved that our own roof leaks may finally be plugged.d said:... my parents suffered from a problem roof for years ... only to discover the hard way that the leak was indeed from a water pipe. (when the pipe finally burst, it was clear that for those many years a slight dripping from an upstairs bathroom had been finding its way to the other side of the house which was but one story.)
They started ten years ago when the roofer recycled some old flashing along one wall-- the flashing looked like it had been used for target practice with shotguns. Every once in a while a heavy rain would hit that wall from an unusual angle, back up the flow, and seep through the flashing holes into the cavity above our kitchen ceiling. It didn't happen very often, but after a half-dozen years it finally worked its way through the ceiling drywall and announced itself.
Over the next two rainy seasons we tried to figure out the problem. Every time we thought we'd cleared the flowpaths or patched the right crack, the next rainstorm would prove us wrong. Finally, in desperation, we started reading home improvement roofing books and decided to check the flashing. Once we pulled up a couple shingles it was obvious. $5 of flashing and two afternoons of labor took care of it.
We stopped the kitchen leak but a smaller leak became apparent in the ground-floor familyroom. That one's been with us for three years of troubleshooting, including re-coating the lanai's Brai torch-on roof. We even caulked a couple cracks in the second-story siding and caulked all the way around the second-story picture window. No joy.
While I was caulking one last crack on a trim board, we think my spouse found & solved the problem. She noticed that the drain holes on the second-story picture windows were plugged with a couple decades' worth of gunk. Rain would hit the window glass, drip down to the frame, and puddle on the outside until it seeped down through the sill & into the wall. She cleaned them out with cotton swabs and now the stain on our familyroom ceiling is drying out. One or two more heavy rainstorms and we'll declare victory!
We used the island's best roofer for the roof coating and they never brought up the windows. I can't imagine how many roofing contractors (and thousands of dollars) we would have gone through before discovering THAT solution.
I bet that if we'd thought to check the drain holes before doing anything else then we would've saved ourselves a lot of labor...