Originally Posted by mae-ling
even one nail located in a valley or between tabs of shingle is amazing how much water it can let in.
Maeling, you're right on about that! I had a leak and searched high and low looking all over the roof and inside the attic. Couldn't find it......finally, during a heavy rainstorm, I went to the attic and heard a persistent drip, drip, drip. Went on the roof the next day, and, sure enough, one measley nail hole in an aluminum valley letting in all sorts of water.