What products for fixing split in lead flashing and for join to parapet coping stone

[lfnfan]

Hi

Poking around on my flat roof and I see a couple of splits in the lead flashing that joins our flat roof to our neighbour's wall. Would be grateful for a recommendation of what product to patch this crack over with. I'm thinking some sort of sealant product but not sure. I've attached a picture.

Similar question - the original sealant that the builder used to seal between the end of the lead flashing and the mortar of the parapet coping stone is splitting. Would be grateful for a recommendation of what product to re-seal this with. Again, picture attached in case helpful.

Many thanks!

 

[noseall]

Hi

Poking around on my flat roof and I see a couple of splits in the lead flashing that joins our flat roof to our neighbour's wall. Would be grateful for a recommendation of what product to patch this crack over with. I'm thinking some sort of sealant product but not sure. I've attached a picture.

Similar question - the original sealant that the builder used to seal between the end of the lead flashing and the mortar of the parapet coping stone is splitting. Would be grateful for a recommendation of what product to re-seal this with. Again, picture attached in case helpful.

Many thanks!

That split has occurred naturally so needs leaving alone. Rather, fit a separate cover flashing piece over the split.

 

[lfnfan]

OK, interesting. Thank you.

So I should get myself some lead flashing and make a little groove with an angle grinder a bit above the existing split, or maybe just try and squeeze the new flashing in to the existing groove.

What should I secure the new flashing with? Something like this: https://www.toolstation.com/soudal-...VuodQBh1aBDlMEAQYASABEgKNmfD_BwE&gclsrc=aw.ds

Thanks again for your advice - much appreciated.

 

[ree]

OP,
Could you post pics showing far more context of the flashing?
What the present detailed pics show is that you might do best by:
Removing the lead flashing from the wall - cleaning it up - checking that there is a 25mm deep chase - & that the lead turn into the chase is adequate.
A short piece of lead sheet 100mm wide turning into the same chase as the existing flashing could cover any splits.
The flashing and patch will do fine with the sealant you refer to.

 

[lfnfan]

Sure - here's a wider pic, with the splits and the sealing crack circled.
The flashing's a pretty long piece so removing it could turn into a pretty big job for me.
Thanks in advance!

 

[ree]

OP,
Thanks for the pic.
Given what you say, & what I now see then simply insert 100mm pieces of lead into any existing chase above each split. These 100mm pieces will act as cover flashing at each split.
The max length of sheet lead is 1500mm per length - each length should overlap the previous piece by 100mm.
Presumably there are no signs of leaks below?

 

[lfnfan]

Lovely. Sounds like a plan!

Glad to say no signs of leaks below, and hopefully the new inserts will keep it that way

 

[catlad]

OK, interesting. Thank you.

So I should get myself some lead flashing and make a little groove with an angle grinder a bit above the existing split, or maybe just try and squeeze the new flashing in to the existing groove.

What should I secure the new flashing with? Something like this: https://www.toolstation.com/soudal-...VuodQBh1aBDlMEAQYASABEgKNmfD_BwE&gclsrc=aw.ds

Thanks again for your advice - much appreciated.

You can just paste some of that over the crack with a paint scraper or similar, put some plaster board scrim in the joint if you have any.

 

[lfnfan]

thanks catlad - sounds like a good alternative option.

Definitely cheaper than buying some lead - that stuff is not cheap!

 

[ChrisJP]

You could also use some flashband and stick a reasonable length over each crack

 

[ree]

OP,
If sheet lead has split under, probably, expansion pressures - then neither Flashband nor chase Sealant will work under the same pressures.
My post #6 is a best practice that works.

 

[ree]

OP,
Are you still interested in your thread?
You still have the question about the parapet mortar and flashing outstanding?

 

[lfnfan]

OP,
If sheet lead has split under, probably, expansion pressures - then neither Flashband nor chase Sealant will work under the same pressures.
My post #6 is a best practice that works.

Roger that. Makes sense. I'm probably going to use Code 3 - bit cheaper than the Code 4. Shame I'm only going to use a small part of the roll.

 

[lfnfan]

OP,
Are you still interested in your thread?
You still have the question about the parapet mortar and flashing outstanding?

Yes, but I was planning a similar approach - scrape out a bit of the chasing and put in a piece of lead, pressed down to shape, and re-seal the chasing. But will be trickier as it's going round the edge of the wall to some extent.

Any advice on this area also much appreciated!

 

[noseall]

But will be trickier as it's going round the edge of the wall to some extent.

Any advice on this area also much appreciated!

leadmate.jpg

• noseall
• 4 Nov 2024

You can actually practice with some paper first, to try and get the bell shape.