Improvement on mortar for valley/gulley tiles ?

Same on our roof. Roofer was s*it hot with slates and lead but knew SFA about mortar. Pva is the answer IME, whether added to the mortar or applied to the surface. Cheap and easy but they won't use it for some reason. Presumably it shaves a fraction of a percent off their meagre profit margin.

If the tiles are correctly cut, no water will leak in a valley even if you haven't mortared it yet, unless there's a really strong wind. If they're mortared and it breaks away, then the cracks in the morter can funnel the water under the tiles. However, it still shouldn't come in as the underfelt and gutter should catch it, unless the underfelt has failed, or there isn't any.

IIRC, I used a 3:1 or 4:1 mix when I pointed my valley. It is kind of tricky to do, as the tiles move when you stand on nearby ones, and it's all too easy to destroy the bond as you work on the next tiles. The mortar should be under the edge, so that if the bond does crack, the water is still not directed into the crack.

In my case, the original leak was due to a broken tile higher up, water running down the underfelt, which had rotted off just when it got to the valley, and dropped into the loft. I stripped it all off and fitted a modern underfelt, and the strip which runs under the valley is not even a breathable one, as I wanted that to be well waterproof.

You've convinced me that *anything* is better than mortaring.

Just had a roofer look at it via some photos I took when I was up there. He's suggested a dry valley system (I have googled it) and says he can do the leaking one and the one the other side (which is the same geometry, just not leaking - yet) with new felt, battens and tiles for £1,800 all in.

I'm inclined to take this, as shopping around *may* get a cheaper quote, but I really can't do with the hassle.

Post the pix up somewhere be interesting to See Jethro...