Cast iron soil pipe

31 Mar 2006
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United Kingdom
Not sure if this post is best off in building or plumbing, but I'll try it here first of all.

The problem I've got is we have an old 4" cast iron soil pipe on the outside of the house, and where this joins to the clay drain pipe, part of the clay has broken away.

I don't really want to replace the cast iron if at all possible as it's going to mean damaging the rendering outside and the bathroom tiles inside which is an absoloute last resort.

There is also a gulley trap near here which has broken too. This has a square salt glazed grate cover which I'm hoping to re-use on top of a new PVC trap.

I was thinking that it would be easiest to replace all the clay pipe up until just after the tee, and joint on to the old clay pipe with one of those rubber adaptors with the jubilee clips round it, but I'm not sure how to join from the new PVC pipe back on to the old cast iron pipe.

I was wondering if I just slotted the iron pipe into a PVC socket and then sealed the joint with some mastic if that would be good enough or if there's a proprietry thing available for the task.

I've added some pics so you can see what I mean.

Old gulley trap

Cast iron to clay joint

Existing layout

What I'm proposing

Overall view

Any thoughts or suggestions are most welcome.

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Your plan to replace the pipe-work to just beyond the 'y' junction sounds good and you can use a fernco type coupler at both ends i.e. salt glaze and iron.

However if rodding access has ever been a problem then it would be an ideal time to fit a mini access chamber whilst you have access.
I did wonder about replacing the y joint with one of those mini access chambers.

I don't think there's ever been an issue before and there is a large access chamber about 4 or 5 m away but this lot tees into another pipe before there.

Are those couplers available in different sizes for the salt glaze and the iron? i've used one onto salt glaze before, but that's about 5½" outside diameter, so obviously will be too big for the iron.

thanks for your help so far.
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If it was me, I would do a clean cut not far from the elbow and use the flex-seal. The problem I find with old clay pipes you have to be very very careful when breaking it away which could disturb more problem further down the line, sometime it's best to leave these alone unless you're confident not damaging any pipes
This is why I was going to replace all the pipework to just past the Y joint.

This will leave me with just one joint on to the old clay pipe, which I will cut square with my sthil saw.

The gulley and all the pipework upto the Y joint is half set in concrete so there's no way I'll be able to replace the gulley without causing damage to the pipework. After the Y it seems to be just buried direct in to the soil.
Well spent all day sweating my bits off and digging through concrete, but got there in the end.

Does this look ok?



Only criticism (nit-pick) would be the lack of a swept rest bend at the foot of the iron stack. Unlikely to affect the running though. ;)
Great job - well thought out and well carried out.

What poor, original design - was this a pre-war, ex-council house?

I'm referring to the siting of the S&V pipe slap bang in the entranceway - there are a number of design issues there.

Only criticism (nit-pick) would be the lack of a swept rest bend at the foot of the iron stack. Unlikely to affect the running though. ;)
Sorry Nose , but the rest bend ( beloved of Council build inspectors ) is only necessary on a single stack system ;) it`s the old chestnut of water/air compressing @ the bottom of the stack . Serving one WC , like @ the OP`s , it`s fine as is , as you surmised
House is a private built house, completed in 1959.

I've chucked some concrete down the hole today to support the pipe and to set the gulley in place. Just need to back fill and re-lay the paving slabs once thats gone off.

Not bad for a sparky :LOL:
Damn you , sparky you`ve done a good job - and you know Ohm`s Law - I`d have been a spark if I could`ve understood maths ;)

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