Valley leaks
Two planes meet and the water has to go somewhere. Debris and worn metal. Not a reroof by default.
A valley is the channel where two roof planes meet. All the water from both sides runs there. Leaves, twigs, and live oak debris sit in that channel and hold water against the metal. The metal wears. Nails pop. The cut shingles on either side curl. Then the stain shows up on a ceiling that is nowhere near a pipe.
Door knock crews see a valley and sell a reroof. A worn valley is a leak. It is not, by itself, a reason to tear the house apart.
What we look at
- Open metal versus a closed (woven or cut) valley, both can leak if the metal is gone or the cuts are short.
- Debris packed in the channel. Water has to move. If it sits, it finds a nail.
- The deck under the valley. Soft wood gets patched first. You do not metal over rot.
Leak barrier belongs under a valley. The flange, the metal, belongs in the shingle course, not tarred on top as an afterthought. Caulk is not the flashing.
If a repair holds, that is the job. A tear-off is for when the system is finished.
Just to name a few: pipe boot, a vent, a skylight, drip edge, a valley, flashing.