Repairing/replacing lead box gutter

17 Sep 2019
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United Kingdom
Have had problems with our lead box gutter/ parapet gutter since a year after it was installed (4 years ago, extension is approx 5 years old). The water is getting through to the inside walls (see pics below). We have had a few roofers up there with the first trying to fix it with Acrypol+, we have also found out that the lead seems to be the wrong code (too thin obviously) and that there is no expansion joint for the length of the gutter.
My question is, going forward what is the best replacement for this gutter as I would like to get it fixed once and for all. I'm presuming replacing it with the correct lead, also replacing the boarding underneath as there appears to be dips which is where the wood is rotting I presume.
Any ideas/input welcome.


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Pics of the roof
Regards Aidan.


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Regardless of code it was always going to fail .
Looking at the pictures I doubt you have enough depth of parapet at the far end to enable it to be replaced correctly .

Simplest , replace in a single ply such as Alwitra or even a decent torch on felt.
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Regardless of code it was always going to fail .
Looking at the pictures I doubt you have enough depth of parapet at the far end to enable it to be replaced correctly .
I take it you're referring to how the soil stack is positioned going through the roof? Is there anyway that this can be corrected? As stated I'd like to get the job done right this time.
Regards Aidan.
No I'm meaning the gutter should be devided up into bays each bay stepped up to form weirs.
Guessing the length from the picture the far end would need to be approx 150mm higher than it currently is. This would give little upstand against the parapet under the copings. Of course you may be able to drop the outlet end . This would be more complicated .

The SVP could simply be boxed in and clad a common detail . But not diy


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Whoever put that lot together isn't a builder!
And certainly knew sod all about leadwork.
Needs altering as above detail.
Alternatively lead expansion joints can be used where its impossible to alter falls.
The flashing round the soli pipe/waste is awfully.
To replace in lead your going to need someone experienced in leadwork and probably someone who can leadburn.
Yes you are correct a neoprene expansion joint or two could be burnt in ..
I had not suggested it because most msnufacters only gaurantee for 10 years ..
Which in my book isn't long enough .
Thanks for all the comments and information. Currently trying to get a lead work speacialist to come over and quote.
Regards Aidan.
Had a local builder quote for this work and he wanted to increase the fall of the gutter then use code 4 lead (all in one run). The length of each gutter is 5m. Going by what has been said on here that seems incorrect. Looking online can't really see what the max length of code 4 would be for one piece.
Can anyone confirm?
Regards Aidan
1.5 MTR as a flashing not a box gutter.
Up the code to 5 or preferably 6 go 1.2 or 1.5 if you must .
Your quote is nonsense. get another quote. search online for Calder's guide to good lead work , it's a simple guide to understand .
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Your local builder has the same skill set as original installer utter rubbish.
Look at details as above as I said before if you want lead experienced leadworker required.
So an update on this issue, decided to go for a single ply solution due to the lack of drips/falls installed for lead to be correct. Apparently its a sika system. One side was done on Monday (see below) the other is being completed today.
Some observations: still have standing water at some points after heavy rain & the lead was left in around the soil stack with the lining being fit under then liquid sealed.
Again any comments appreciated.
Regards Aidan.

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