UPDATE: New album with additional photos here: http://imgur.com/a/RGfrP
My parent's house has a pretty bad leak that has been going for a few years. Because of money and other issues with the house I need to try do an improvement myself if at all possible. Getting a new roof (or house, since everything else is outdated/has an issue) may be possible down the line but not right now.
One thing slightly in my favor is this is in San Diego so it rains infrequently.
I have included some pictures. In the last you can see where I pulled some of the ceiling down where it was mostly soft/mushy. Asbestos test was negative.
Estimators have suggested the issue is definitely with the valley and one of them recommended I could install flashing in/along/under (not sure what he meant) the valley to improve the situation. I purchased a roll of aluminum flashing. I am not clear on exactly where to put it though.
The examples I see on youtube when I search 'roof valley' don't have such a low slope or the part where it goes up/horizontally again like that. The ones I saw were mostly just one smooth seem. If it was like that then I have some tutorials on doing underlayment, flashing, trimming shingles for a normal valley. But I haven't seen an example quite like my roof.
Thanks so much for any advice.
Best Answer
Yeah, that roof's pretty beat. I'd actually go heavily at that seam with Mortar Caulk (its gritty & gray), the whole length of the seam if you don't know where the leak is. But, spraying a hose at the seam & very slowly moving the spray up the seam should give you a good idea of the problem area.
Still caulk the whole seam, but then do under the shingles in the leak zone. Be careful & don't pry them anymore if they're brittle & chunks start snapping off. I caulked a flat roof in the rain 3-years ago & it still hasn't let in a drop.