In article . com,
"dg" writes:

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...

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.

Thanks.

Didn't get to the flaunching today -- that will be tomorrow, or
Wednesday if I need to buy more tiles.

I would like the tiles to overhang the flaunching slightly, so
that even if the tile to flaunching bond breaks, the water still
goes into the gulley. However, that makes it really hard to get
a good finish under the tile edge. The way it was done was the
flaunching was brought up in front of the cut tile edges and
made level with the tile top. This may be because, having removed
the flaunching, I can see the cut tile edges are not in a very
straight line, which the flaunching was making up for.

Still thinking this one through...

--
Andrew Gabriel