Repairing cast iron gutter

18 Feb 2010
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West Lothian
United Kingdom
As the title suggests I have a cast iron gutter that is leaking at the joints. There is scaffolding up for other work. I know some will straight away say replace, but replacing in plastic is not an option (conservation area) and to buy a like for like replacement that the planners would accept is beyond my budget!

I know that the traditional repair is to remove the gutter and putty up but given the age of the thing I would rather not risk removing it if possible and I wondered if anyone has experience of brush on repair materials in this context.

I saw this Roofix 20/10 stuff on toolstation and it gets great reviews there and on Amazon, and supposedly stays flexible.

Any thoughts, alternatives, gladly received.

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Those sort of products work well in the shopping channel ads on a clean bit of gutter, but usually not in practice with years of C**p on them.
If you have scaffolding then I would split the joint and remake it with a black gutter mastic.
Usually only held with one nut and bolt, cut /grind the nut off underneath and with a little bit of levering it should come apart. Surprisingly the screws fitting to the gutter board if they are the proper large headed ones often come out pretty easy if you need more movement.
Traditional repair is to split the leaking joint:
Cut/Grind the nut off the bolt and use a woodern wedge to open the joint,
clean all the old putty off with(old) blunt chisel or broad screwdriver,
Wire brush loose rust,
paint cleaned surfaces with (old) oil paint,
Whilst still wet putty the lower joint face and re-fix with gutter bolt - tighten up so that the water channel is level on both sides of the joint.
Clean up/off the surplus, squeezed out putty.
After 24 hours over paint the joint on all sides.

Or you could clean out the gutter (yes - all of it) and then apply a 5mm coat of 'Acropol' or similar. But do make sure the gutter isn't painted with any Bitumous paint...

If it is then it will need priming with the correct primer.
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Thanks folks. I know the traditional way to repair is to remove, but on my inspection I have a bad feeling that I would be opening up a can of worms by dismantling that gutter, I can't see the bolts and its not completely clear how its being secured, and the masons have pointed the bottom of it to the cornice stone so it may even have been bonded to the stone underneath it for all I know. Having said that the gutter itself seems fairly solid, and its really just leaking at the joints.

The Acropol looks good, and sounds similar to the Roofix I mentioned before. I don't think these are "shopping channel" type products as footprints said, but my worry is whether they would cope with movement. My inclination is to force some kind of sealer into the joint, whether it is traditional linseed oil putty or a modern sealer, and then paint over the top with Acropol/Roofix type stuff trying to create a one piece membrane if possible.

A mad thought I just had (cue laughter from everyone else), was as a belt and braces to fit a cheap half round plastic guttering inside the existing gutter. I know it seems a bit weird but it would probably fit snugly in there, wouldn't be seen from below and would keep at least 95% of the rainwater away from the joints!
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I don't think any of us realised it was a gutter bedded on to masonry - that makes a lot of difference. However your inner gutter idea isn't so mad;) Perhaps line the whole length with Flashband or similar - you don't need to do it in one length because overlaps stick well - and it's primer is bitumen based:idea:
I should probably have been clearer on that Nige. I am not certain that it is bedded to the masonry, but it sits on top of the cornice stone and there is pointing between the cornice and the gutter so there is chance that it is bedded on. I don't have any real experience with roofing but I was a mechanic and a technician, and sometimes you look at something and think there are going to be complications in taking that apart!

Flashband sounds like a good option, I had thought about lead flashing and shaping it into the internal shape of the gutter, expensive but still a lot cheaper than replacing the gutter, but its what to do with the corners. A long, broad length of flashband would cover most of the joints, and 2 out of 3 of the corners are above the porch so easy to get to if they need resealed later.

Too many options now, need to make a decision!!! :confused:
Thought I would just update this to say what I did in the end. Pic below shows how the gutter sits on the stone. I think its actually originally clipped on to a wooden strap at the back but is effectively sitting on top of the cornice stone, and its looks like slates would need to be removed if it was to come off.
2017-08-15 16.20.52.jpg

Below is one of the joints before I started, the design of the gutter means that water sits between the joints so the putty, or the flashband in this pic is almost permanently submerged. I also found in a couple of places that the gutter had been broken at the back and the flashband was an attempt to seal this but water was just running past the flashband and out the back of the gutter into the wall. I repaired these with chemical metal before proceeding.
2017-08-15 16.21.05.jpg

Below is the same section of gutter after. I filled all the joints with putty first, then cleaned and painted with flashband primer, the lined the gutter with a single piece of 220mm width flashband the full length of the gutter (about 6 metres) spanning about 5 joints, with one end terminating near the downpipe, and the other at the corner pictured and raised above the static level of the water. This means that one sealing edge of the flashband is at the dryest part of the gutter beside the downpipe, and the other is at this corner above the porch where I can easily access it to check and reseal if necessary. I painted over the flashband with the remaining primer, mainly for an extra seal at the joins, and was thinking about painting over the whole thing with bitumen paint.
2017-08-17 16.48.25.jpg

Poring rain last night and no leaks but I suppose time will be the teller!
Just keep applying the lotion.
Nice slate, don't like the look of the etching in the valley lead.. is the rest ok?
The lead is not in great condition in the valleys, it has had a couple of patches and will probably need replaced sometime in the near future. Having said that there is no evidence of any water ingress on the inside of the roof, and the next priority is a chimney rebuild that I can't do myself and which will probably drain the available finances for a while.
Given that you have no leaks then why not wait on doing any roof work until you have funds for every remedial item - that way you only pay for one erection of scaff.

CI guttering sitting on stone will typically rot out from the almost permanently damp gutter bottom thats permanently in contact with the stone - all rainwater will trickle under and sit on the ledge, touching & condensing on the permanently unpainted gutter bottom.

FWIW: quite how that valley hasn't leaked is a mystery.
For instance, you have Code 3 lead when it should be Code 4 or 5.
Plus it looks to be poorly "designed". But if it works it works - so dont do anything until you are totally ready to do the lot.
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CI guttering sitting on stone will typically rot out from the almost permanently damp gutter bottom thats permanently in contact with the stone - all rainwater will trickle under and sit on the ledge, touching & condensing on the permanently unpainted gutter bottom

all cast iron gutters rot from the back first,
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whats your point?
and why the capitalising?
perhaps, given the difficulty you still seem to have with simply expressing your point, you find yourself shouting?
unfortunately, inarticulate roaring isn't an argument.

Your referenced "expert" doesn't appear to know that a sprocket is part of the eaves area timber detail.
Neither does he explicitly consider CI guttering sitting on masonry.
Occasionally roofers refer to a socket end - which, of course, means the female end.
However, we have always referred to CI gutter ends as male & female.
It keeps it simple.
Capitalising was automatic when I quoted from his site.
My point! The gutter rots from the back first, always does on ci rainwater imply it rots from the bottom.
The term sprocket is used in gutter terminology where I am as well.

It is important to highlight where the gutter rots first as that is where it is fixed by coach bolts to the plate attached to the rafter ends.
Attempting to do a repair on a joint when the gutter is supported on a narrow plinth with nothing holding it in place can cause the lot to come down.

That Vinn is where inaccurate advice can become dangerous.
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Hi Folks,
To be honest, I know nothing about lead codes, but I wouldn't be surprised if it was the wrong type, and there are one or two flashband patches here and there. However, there is no evidence of leaking and I have closely inspected the loft and it is dry as a bone in there.

We only bought the place at the end of last year and it has previously suffered from a lack of maintenance and neglect and there is a very long list of things needing done, hence the reason that I am doing whatever I can myself, although I would be the first to admit that rebuilding a sandstone chimney is beyond me and that is why that is the next priority - also because it is heavily patched and is a possible cause for dampness we have on that gable end.

One of the first things I did when I was up there was check that the gutter was secure, I gave it a good yank and its securely stuck in place. In this case it's certainly true that any rot is at the back although only at a couple of points, surprisingly although its almost always under water the bottom of the gutter seemed solid. The scaffold is due to come down soon as it was up for replacement of the cornice stone which was badly cracked and worn. More scaffolding would have been required to replace the whole gutter as the scaffolding that was up was only to one half of the house so it wasn't a case of doing it all when the scaffolding is up. It made sense to repair the section that was accessible to me while the scaffolding was up to protect the new stone underneath, event if it is only delaying the inevitable for a few years.

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