Broken branch off shared waste stack

[gjscott75]

Just looking for some advice... I had a plumber fit a new bathroom suite in my flat recently and he broke off the entire cast iron branch/tee that connected the bath to the shared waste stack (also cast iron). Skipping the argument of whether, in his words, it just came off in his hands or whether he was being a bit ambitious with a hammer, he 'fixed' it by running a smaller diameter PVC pipe into the hole in the stack where the branch once was, and filled around the (irregularly shaped) hole in the stack with silicone sealant. That was a couple of months ago, but just this weekend my downstairs neighbour woke me from my slumber to tell me her ceiling was wet and a wall was soaked enough to cause tiles to come off in her hands. I went down to have a look and, as I believe is typical for these type of tenement flats, the shared stack is hidden away in a boxed area that runs vertically inside each flat, so we managed to saw into the box and see water running down the outside of the stack from ceiling level, so it was almost certainly coming from my property. To cut a rambling story short, it turns out that a hole had developed in the silicone which is where the leak was coming from. I had an independent plumber come out and look at it and his opinion was that using sealer in these circumstances was definitely not recommended and that to fix it properly would be to replace the piece of main stack, a not inconsiderable (or inexpensive) job from what he said.

The original plumber has since been back out, and has applied more silicone sealer over the top of the old stuff and 'guarantees' that it'll hold this time. I'm obviously nervous that the neighbour is going to get her bathroom repaired only for this to all happen again in a month or six. Is silicone sealer an acceptable/reliable solution to this problem, or is there some sort of collar type of thing (like a strap boss, but tall enough to patch the 200mm or so hole in the stack) that would be more effective than sealant, or should the section of stack be replaced as advised by the independent plumber?

Advice, comments and observations gratefully received!

 

[sime10]

Is silicone sealer an acceptable/reliable solution to this problem, or is there some sort of collar type of thing (like a strap boss, but tall enough to patch the 200mm or so hole in the stack) that would be more effective than sealant, or should the section of stack be replaced as advised by the independent plumber?



You say 200mm that seems a bit big are you sure ?

 

[JohnD]

I think it neeeds fixing properly.

If I were you I would be ringing my insurance company. They might want to make a claim against the plumber.

Sewage running down the duct into your neighbours flat could cause a big claim, and cutting out a section of cast iron pipe, though possible, may end up causing more damage, especially if the stack is not well-supported.

 

[gjscott75]

Is silicone sealer an acceptable/reliable solution to this problem, or is there some sort of collar type of thing (like a strap boss, but tall enough to patch the 200mm or so hole in the stack) that would be more effective than sealant, or should the section of stack be replaced as advised by the independent plumber?



You say 200mm that seems a bit big are you sure ?

Nope!

I'm guessing it's a hole of roughly that size in the shared stack. The branch that came off the stack certainly wasn't 200mm diameter, obviously, but the branch took a bit of the stack with it and left an irregular (but I guess roughly circular) hole in the stack.

The amount of filler used might give you an idea of the size of it...
http://pljy58760.pwp.blueyonder.co.uk/DSC00040.JPG

 

[sime10]

Looks a bit of a mess I would renew it. It will more than likely leak again

 

[gjscott75]

I think it neeeds fixing properly.

If I were you I would be ringing my insurance company. They might want to make a claim against the plumber.

Sewage running down the duct into your neighbours flat could cause a big claim, and cutting out a section of cast iron pipe, though possible, may end up causing more damage, especially if the stack is not well-supported.

Ahhh, insurance companies, don't get me started

To be honest, there's no real damage to my property, all the damage was in the downstairs neighbours (well, apart from the fact that the stack is behind a tiled area which I had to smash to get into... so the damage in my property runs to the cost of replacing a dozen or so tiles). I phoned my insurance company anyway and they said that if the problem is the result of poor workmanship by someone I hired, I'm not covered. Obviously, the woman downstairs will make a claim on her own insurance to get her place fixed, and I suspect that may mean her insurance company makes a claim against my insurance company. I'm sure that side of it will all become clear in the next couple of weeks.

 

[gjscott75]

Looks a bit of a mess I would renew it. It will more than likely leak again

Do you mean renew the broken section with a new piece of cast iron pipe, or implement a better fix than just filler (perhaps with the collar type arrangement which, admitedly, I may have just invented)?

Is replacing the section of broken pipe a job that a 'regular' plumber could undertake (no offence to regular plumbers), or is this a specialist job given that I presume there'll be a requirement to prop up the top half of the (presumably very heavy) cast iron stack so no further problems are created upstairs if the stack were to drop, plus perhaps some welding?!?!

I've got a feeling this may cost the sort of money that requires me to become very familiar with the bank manager

 

[sime10]

Not sure exactly what I would do I would have to look at the hole underneath the silicone and see what its like first.

Are you on the top floor?

 

[gjscott75]

Not sure exactly what I would do I would have to look at the hole underneath the silicone and see what its like first.

Are you on the top floor?

Nope, got a further flat above me... it's about 12ft floor to ceiling in these flats and the break is right at floor level in my property so there's at least 12 ft of pipe above the break plus however far up the stack rises in my upstairs neighbour's property.

 

[Gasguru]

There appears to be a 4" branch a little further up to complicate it even more.

I think I'd take off the silicon to see the size of the hole.

If its not too bad prepare the surface with a mini grinder and silicon on a strap on boss.



The knuckle bends on the new waste pipe are another indication of a bodge.

At least its not as bad as this one I found - plastic waste pipe and flexible pan connector bodged onto LEAD with chemical metal

 

[gjscott75]

There appears to be a 4" branch a little further up to complicate it even more. ]

Yep, that's where waste water from the kitchen comes into the stack, I think.

I think I'd take off the silicon to see the size of the hole.

If its not too bad prepare the surface with a mini grinder and silicon on a strap on boss.

Yep, I was guessing the hole was 200mm but, in hindsight, it would seem unlikely. There's perhaps about 200mm width of silicone caked onto the hole, so obviously the hole will be smaller than that. Like you say, I'd need to take it off to get a proper look at it but, from memory of just before the plumber started repairing it, the thin strap on that boss would (I think) still leave some of the hole showing. I've photoshopped your image to show what I think would cover it... basically the same thing, but with a more substantial strap.

The reason I'm trying to find out if such a thing exists is because it's possibly something I could fit myself, but I would need to remove the bath to get decent access to the pipe... and the bath can't be removed without removing a cabinet and WHB because of the layout. It's no small job (for me, that is) and I wouldn't like to start it all, get everything out of the way, strip off the silicone and discover the hole is too big to be covered by a normal boss and my options are then either replace the section of cast iron pipe (which would need a professional), or just put silicone back on.

The knuckle bends on the new waste pipe are another indication of a bodge.

Indulge my ignorance of plumbing ... why is this an indication of a bodge?

 

[sime10]

Gasguru if that was in gasinstaller that would defo be a free camera lol

 

[sime10]

gjscott Have you thought about moving ?

 

[Gasguru]

I can't see where you get 200mm from.

200mm = 20cm =8 inches

The new white waste pipe is approximately 40mm (4cm or 1.5 inches) in diameter.

Looking at the silicon the hole can't possibly be 200mm.

The image of the boss I posted earlier is typical of the makes available.

Alternatively you could try this from Marley



The main problem is going to be obtaining a good seal - hence the need for cleaning up the cast iron and the differing thermal expansion rates between cast iron and plastic giving long term reliability.

http://www.marleyplumbinganddrainage.com/sw_product_detail.asp?product_category=sW_Vent_Compts

As for the bends it is better to use a swept bend as the pipe runs from a vertical to horizontal incline rather than the tight (knuckle) bend you have.


As for the bodged up lead stack its still being discussed by the freeholders of the flats. There were two other leaks higher up where the copper wastes had been sweated onto the lead. The only viable solution is a new external stack and as bathrooms are upgraded they can be connected into it. Luckily this bodge is a top floor flat.

 

[sime10]

Gas he has already admitted to the 200mm not really bit, How can you have 200mm in a 4" pipe

I was commenting on your what to do in plumbing part one pics