Andrew Gabriel wrote:
Any suggestions for the flaunching mortar mix for a valley gutter?
I've seen 1:4 recommended for flaunching around chimney pots, so
I assume this is not wildly out.
What about the sand -- sharp sand or building sand?

Guess who's repairing his roof today...

--
Andrew Gabriel

A 4:1 would be fine.

I would use building sand for workability, but add some sharp sand too
for weather resistance 2:1 0r 3:1 ratio. Some PVA will also help.

But remember, its not so much the mix, but the trowelled finish that
will give it the tough surface and greater weather resistance.

dg