Flashing for roof abutting a render/lath wall

[oldhouse22]

Hi
I am interested to hear what people think about the best way to "flash" the abutment of a roof against a render on lath wall.

There is currently a (failed) cement fillet there at the moment, without soakers, and we get water in the house whenever there's heavy rain.

The roof needs a felt and batten to take place anyway so all the tiles are coming off, and we'd like to ensure that the method of weatherproofing this joint will last a decent amount of time.

The roofers I've spoken to all seem a little stumped when I point out that they can't just stick a bit of lead in there, I'm concerned that replacing it with more cement is not going to stand the test of time, and wondered what the "correct" method would be. I would try to find other roofers to comment but unfortunately our choice of roofers is limited to those who will actually return calls.



Ideas?

 

[Kearn]

First question, is that lime? Looks suspiciously like it may not be. If it isn’t, that won’t be helping with water ingress at all. You’ll have big cracks where water can find its way through.

In terms of flashing, cutting lead into the panels isn’t the worst thing you can do. Needs to be sensitively done by a decent lead worker and dressed up at the right angle into the render/panel. And you’ll probably need to do some ad hoc lime patch repairs after.

 

[oldhouse22]

@Kearn thankyou for your response.

is that lime?

The existing flashing is cement and certainly has been letting water through; that's reduced after adding sealant but is still letting in water.
The wall may well be cement where it reaches the flashing, but I am pretty certain it's lime at the top where it's still on what I guess is the original wooden lath (will grab a photo when I next go in that loft).

cutting lead into the panels isn’t the worst thing you can do

If they do that, what holds up the wall lower than the cut? I have no idea how thick the render is but would a slot not compromise the integrity of it if they slice through the lath?

 

[alexander]

cut the render back to the wall adjoining the roof install soakers & stepped flashing, re-render the wall, or seal against the wall with a lime mortar against the existing wall.

 

[a twig]

I think @MikeG had a similar issue on his porch which he initially filleted and then ended up using lead but haven’t seen him about for a while