Cutting a new inlet into cast iron soil pipe?

Hi All

We're just about to embark on putting a new bathroom suite in, and I've spotted a potential issue.

Our soil pipe runs internally down the corner of the house, boxed in obviously. The existing toilet in the bathroom is a P trap with a 90 degree horizontal pipe that goes straight into the adjascent soil pipe all above floorboard level, but its hidden because everything behind the loo (including the remote cistern) is all boxed in.

The new loo is also a P trap but its a close coupled cistern so the back of the loo cant be spaced and boxed in the same way as the old one, which means we need to have the waste pipe go vertically down through the floorboards behind the loo then turn 90 degrees into a new inlet on the stink pipe about a foot lower down than the existing inlet.

Being internal I assumed the soil pipe would be plastic but having pulled some of the boxing out this morning I find that its cast iron, so how the heck do we cut into a cast iron pipe to put a new inlet in, and if thats not possible, what are our options?

cheers
Chris

 

A few of the houses near me must have experienced problems, perhaps of similar nature.
All I've noticed is the 'internal' soil pipe has been modified. Most of it has been removed internally.
They now have a external pipe, but it still goes back internally a few feet up the kitchen wall.
Toilet pipe now goes straight outside before bending and feed into vertical pipe.
Just thought it maybe a option for you to consider.

 

To cut the hole you use a hole saw with the right diameter. Take it gently and it shouldn't be a problem.

 

Hi Oilman

Thanks for that, would you be able to get a seal having cut into it then, I assume by using one of those strap around connectors you can get?

Having investigated further this afternoon and had a look under the floorboards though, Im not sure there's a lot I can do with it anyway and it may end up being boxed in.

The problem is the existing inlet into the pipe is via a separate cast T piece that sits between the upper and lower pipe, meaning there's a bloody great joint in the pipe just below floorboard level, right at the point where the new inlet needs to go in! The only way I can see it being possible is to take that section out completely, cut the lower pipe down further then getting a new longer T piece to fill the gap.

I guess the other alternative is to replace the entire pipe with plastic, the bit inside the house wouldnt be too much of an issue as we're also re-doing the kitchen at the moment so would happily rip out the boxing on both floors, but the part that concerns me is the top section in the roof that goes through the tiles and is sealed by lead flashing. From looking outside, it would appear there's a lead "tube" that the pipe itself passes through, but I assume I'd need a roofer in to re-do all that, its not simply a case of sliding out the old pipe, sliding a new one up then sealing it up to the lead from the outside?!

cheers
Chris

 

The best bet could be for you to cut the pipe as low down as you can go and put in a fernco coupler (many different sizes) replace with 4" plastic with a junction at the right height, then do the same as high as you dare go (if you don't want to redo the lead slate) then all you need to do is make good the boxing.

 

Thanks RHS, I shall investigate, Im assuming you're talking about something like this?



Due to its position and having joists in both directions around it, its going to be a pig to cut below bathroom floor level but I could cut the pipe just below ceiling height in the kitchen to give enough room for the coupler I guess. If I do go down this route, what would be best to cut it with, as Im not sure if you'd get a large enough disc cutter in there, so a chain cutter perhaps?

thanks
Chris

 

That looks good enough, I would say cut out the boxing and make a good job of the plumbing as you don't want leaks from your soil pipe

I have used a disk cutter in the past (always make it easy for your self it pays in the end.....short cuts are for cowboys)

 

Or did you mean two conventional straight rubber couplers with a plastic Tee in between? Both would do the same job I guess, all the suppliers of the flexible tee in the pic above seem to be in the USA anyway, so are they unsuitable for UK building regs or something?

 

I meant 2 couplers, I think the USA use a different size

 

Take a look on here, we bought a cast iron soil branch from http://www.heritage-supplies.com took a bit of fitting but well worth it.

 

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