"Phil L" wrote in message
.uk...
VisionSet wrote:
I've just redone the flashing seal with the brickwork on my flat bay
window roof. The depth inserted is about 15mm so a bit less than
recommended. I've directed a hose at highish pressure along the joint
for a few minutes, but it still leaks. I've simulated I guess an
attrocious storm but that's not really acceptable I don't think. Can
I treat the mortar I've applied with some silicon treatment to reduce
ingress further? Or what?

TIA,
Mike W

You'v probably washed the mortar out of the joint... I would suggest
taking
it all off and starting again, no amount of silicone will ever seal it.
If it's a long piece of lead (more than 3ft long) you will need two people
to get it in to the right depth, (25mm+) use an angle grinder with a
diamond
disk in it (new, preferably so you get the deepest possible cut) and wedge
it in with small rolled up lead wedges.
Point with a strong mix 3:1 and hope for dry weather for 24 hours.


15mm turn in should carry ok, I've seen less turn in with no leak, yes I
know its recommends 25mm. One of the problems with leaking lead/brick joints
is that the mortar is not push in to the back far enough. If you cant get
the recommended 25mm. Take out the next joint above and put an apron over
the whole lot so it covers down to the flat, cloaking the joint below. This
will give a greater up stand.