Soil pipe fittings - Connecting plastic soil pipe to castiron

[mulls]

Hi,
Not sure if this is the right place but....I need to move a wc about 800 mm to one side to make room for a shower cubicle in a corner. The existing cast iron soil pipe exits through the floor and goes through a cast iron 90 deg bend into a straight length of cast iron pipe off at right angles to the wc. I would like to remove the existing 90 degree bend and extend the remaining cast iron pipe with a plastic pipe to the new wc location - using a further plastic 90 degree bend to complete the job.

My questions are: How do I separate the existing cast iron joint and then how can I fit the new plastic soil pipe to the cast iron straight length?

Are there any reasons why I shouldn't do this?

Any help and advise very welcome. Thanks.

[Tony McC]

I'm not sure about how easy it would be to dismantle the CI pipework. It has a tendency to self-seal and the usual remedy is a big nangle grinder.

When it comes to attaching the new placky fittings, your local Plumbers' Merchant or Drainage Centre hould be able to supply adapter couplings for connect CI to uPVC

[mulls]

Thanks very much - I'll get down the plumbers merchant for the adaptor. For info. though, do you know if I can use one of the flexible adaptors held in place with big jubilee clips or is this not suitable for foul waste?

Thanks again.

[flowjoe]

Hello All

There are loads of adaptors for above/below ground plastic to cast/clay/pitch fibre pipes, the problem with cast iron is that it is usually in an imperial measurement and this can range from 3 to 4 inch and anywhere between.

Try to get an external measurement first but unfortunately you normlly need to cut first and try several adaptors if your lucky one will fit, if not discreetly seal with a sealant.

Band Seals/Flexi Adaptors are unsightly above ground and look bodged, if you use one make sure it is designed to be above ground and that the bands/jubilee clips wont corrode.

Cast is a nightmare to dismantle without breaking/cracking so we would normally way up the pros & cons and cost of renewing the entire stack in plastic if finding a suitable adaptor is proving difficult.

Cheers

[flowjoe]

Sorry about the above font

If the wind changes your face will stay like that

[mulls]

Thanks. I've found a plastic to cast iron adaptor in Wickes.

Its an odd looking thing (to me, not you experts) which has a rubber seal for the plastic (fine) and there appears to be a 4 inch section the other end which must be for the CI. This section looks as though it should be packed with some sort of sealant as I can't see how else it makes a proper seal - I'm guessing! Can you advise me whether I am correct and if so, what sealant should I use.

Sorry I'm a bit ignorant here - I've never re-plumbed a soil pipe before and want to know what I'm doing before I start the job.!! :laugh:

Thanks.

[danensis]

I think you are supposed to use tarred hemp aren't you?

[mulls]

can anyone confirm this? Thanks.

[flowjoe]

The cast iron adaptor has no seal because as i mentioned earlier the size of the cast iron pipe wall can vary in thickness.

Get the external measurement of the pipe and go to a decent builders merchants, Travis Perkins/Buider Centre (other b.m are available bla bla) and try several adapters.

Hep-sleve to plastic or super-sleve to plastic are your best bet though if it is a thin wall cast iron a plastic straight connector may fit.

If your lucky one of these rubber sealed adaptors will seal the connection, if not seal wih a mastic based sealant though make sure you are sealing onto the cast iron and not the several layers of flaking paint added over the years

[mulls]

Thanks for all your help on this one guys/gals. I've now been to TP and they seem to have an adaptor which should fit.

Great site BTW.

Cheers.

[ALANG]

Do you need building regs approval before changing/replacing a soil stack, flowjoe!!!

[flowjoe]

I think most BCO would be pleasently surprised to be notified if you are replacing a cast soil vent pipe for a plastic one, though technically you should notify them and rightly so, i have in the past found re-positioned SVPs to be obstructing windows and covering vents/flues.

[mulls]

My property is not on the water mains (we use a well) and soil drainage is to a septic tank. Should I still inform BCO/water authorities under these circumstances? Thnx.

[flowjoe]

Were you born their or did you parachute in ?

Cant do any harn to speak to your BCO, just because you dont dischrage into a sewer does not mean you are not subject to building regs.