Cast iron soil stack

[erikwoolf]

Previous owners had to fit new soil pipe connections so they cut a piece of the cast iron soil stack and fitted the plastic connections. Put a scaffolding up to repair some guttering and found that the connection is misaligned. Roofer was not confident to replace and suggested to call a plumber. I don't want to waste my time if this is going to be a faff to fix for little benefit (we are based in London and finding plumbers to do little jobs like that is a real hassle). Any views to what extend this is DIYable?

 

[Kearn]

Not quite following what’s plastic? Have they added in a section of pipe with bosses for waste?

You can get these in cast, if that’s what you’re after.

It’s a real pain though, especially depending on the sealing method chosen which may be permanent.

Cutting through a cast pipe is also no fun.

If it’s just the bend, but if everything is functional and sealed, then I’d pick another battle!

 

[Stevers]

Doesn't it just need straightening and perhaps an extra bracket?

Fittings are available new for '100mm' cast iron (at a price), but whether they'd fit your pipes is a moot point. I'd start by looking for a solution to your problem in the local reclaim yard. If anything needs cutting to length a cast iron soil pipe will be no match for a metal cutting blade in an angle grinder - PPE assumed.

 

[Cubist]

I think I've puzzled this one out now. The section below the collar is cast iron with the plastic pipe above it. Given that the plastic pipe rises through the eaves then this section, and much of the pipe below operates as a breather to allow the escape of noxious gases rising from the main sewer line. However, there would also be a T connection to the iron pipe further down to allow exit of waste and water from any 1st floor WCs.

So three possible problems. First would be a gas tight joint between the plastic and the iron pipes, the second being that the joint of the T from indoors may have been compromised by the movement and the third being a need to stabilise the connections of the pipe to the wall to prevent future movement. All of which can be easily fixed with an adaptor, a couple of brackets and some sealant from the likes of Screwfix and well within the capacities of any DIYer.

However, the extra mile solution, would be to replace the now missing section of cast iron pipe with a new section. Heavy and perhaps hard to wrangle back up through the eaves?

 

[erikwoolf]

Not quite following what’s plastic? Have they added in a section of pipe with bosses for waste?

You can get these in cast, if that’s what you’re after.

It’s a real pain though, especially depending on the sealing method chosen which may be permanent.

Cutting through a cast pipe is also no fun.

If it’s just the bend, but if everything is functional and sealed, then I’d pick another battle!

Thank you, the top part that you can see in the photo is old cast iron, where the bend is and below is the new plastic connection and underneath that is again old cast iron. It is functional and doesn't leak it is more about getting it straight and attached to the wall rather than how it is now.

 

[Flyfisher]

Looks to me as if the pipe has only bent outwards at the joint because it has not been fixed to the wall.
I suspect there will be enough play in the joints to allow the pipe to be pushed back against the wall and then fixed into position.

Given that there is scaffolding in place, it would be very easy to try pushing the pipe back into place. Then, depending on how purist you want to be, it would be very easy to fix the pipe into position using a suitable bracket. Modern ones are plastic of course, but would be hardly visible from the ground, especially if fixed immediately above or below the existing plastic joint. Something like this https://www.screwfix.com/p/floplast-pipe-clips-black-110mm-5-pack/76037 but a quick online search will find other variations.

If bending the pipe opens the joint slightly then something like Plumbers Mait would probably be easy to push into and seal any slight gaps for an airtight seal. It looks as if this is only a vent pipe so almost any flexible sealer will do the job of making it airtight.

 

[Cubist]

Then something like a couple of these will do the job I suspect. But, you would be wise to check and repair any damage to the roof and whatever gasket/flashing was used to seal the exit around the top of the pipe and over the tiles as well.

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[Flyfisher]

Fair point about the roof flashing. Hopefully the scaffolding extends to the roof, which would make checking this very easy indeed.

 

[fernicarry]

There will be a rubber collar on the top side where the vent pipe protrudes from the eves. Check that the upper piece hasn't slipped down under its own weight and distorted the collar. That's' what happened to mine when we chopped out a section to put in a new branch, but it does seem to be working well enough.