How tightly should lead flashing be dressed to a NOT flat old stone wall?

[Black Timber]

Hi all

I've finished installed soakers to my slate roof at a wall abutment, and I've cut the chase above ready for the flashing. The chase isn't mega straight, especially the bottom line This is mostly due to bits of stone and mortar falling away. And partly lack of skill On top of that, the vertical bit of wall that will be behind the flashing undulates and is anything but flat.

I've dressed the soaker upstands tight to the wall. Should I do the same with the flashing or does it not need to be dressed so tightly?

Also, I was planning to keep the bottom of the flashing about 10mm above the slates. The upstand would then be around 115mm, with 35mm tucked into the chase. Where the chase is lower than 115mm, does it matter? IE - with the lead at 115mm upstand, but the bottom line of the chase only 100mm, there will be a small void behind the lead. Is that ok as is? Or should I look to pack it somehow?

I hope this all makes sense! It's been a long day. I'll try and add some photos shortly.

Any advice much appreciated.

Many thanks

 

[Stevers]

That all sounds good to me, the big thing is to get the fold at the top of the flashing nicely tucked into the groove and secured ready for Leadmate or CT1 equivalent. I drove little rolls of lead into the gap to do this, but you can buy some sort of fancy clip to do that too. If the gap is a bit variable the little rolls of lead can be varied in size to suit. I like the lead rolls as there are always offcuts knocking about to make them. Properly secured the flashing won't go anywhere even if not tight up against the wall. I think you wrote earlier that you were doing a diagonal chase like mine. My flashing had 'S' straps in lead hooked over the soaker tops and hooked under the edge of the flashing. They helped to support the flashing during installation, but whether they do anything once it's all finished I wouldn't like to say.

 

[Black Timber]

Many thanks for the reply and insights. And the photo. All really helpful thanks.

Yes, you're right, mine is a diagonal flashing like yours. I've already bought some hall clips and plan to use those. I've never done anything like this before so thought the extra help was worth the expense! The accommodate a chase between 6 - 18mm wide so should be good.

I'll post some photos below in case they help shed light on what I should or should not being doing.

Thanks again

 

[Black Timber]

That all sounds good to me

Thanks for the vote of confidence I posted on another forum where the advice was to recut the top line and mortar up the bottom.

So I'm currently deciding what to do best, although in all honesty I'd much prefer to not recut it, for various reasons.

Any further thoughts much appreciated on my original post and/or whether anyone thinks it needs recutting...

Cheers

 

[Stevers]

Sections of the groove aren't ideal perhaps. Rather than recut, I think I'd stick a piece of wood of suitable thickness wrapped in plastic where you want the groove to be and point the worst bits over and under it. If you use NHL that might be good to go the next day. I would gently wiggle the wood whilst the mortar is setting to make enough room for removal and break the bond.

There's probably a limit on the length of each flashing piece. When I looked into valley gutters, Code 8 was limited to 8' and Code 4 was limited to 4' - something to do with thermal movement and cracking, but handling is a consideration too.