1930's toilet waste - Clay to PVC

[Anto74]

Hi-
I am new to this forum, which has been to be a fantastic source of information for me, so thank you for all the useful tips.

I am redoing a cloakroom in my 1930's house. The toilet waste seems to be in clay and I am looking for advice on how to connect it to PVC. See enclosed picture.

I am not changing the layout of cloakroom and will put a cistern in a box and use a swan neck connector to connect a floor standing, back to wall toilet.

The current porcelain toilet waste pipe has a 100mm diameter and has been cemented in the top of the clay pipe which visible part is approximately 190/200 mm.

I was thinking to cut the top of the clay waste with an angle grinder to floor level and use a clay to PVC mcalpine connector in which I will put a mcalpine adjustable length swan pan neck connector.

I have few questions:

- In your experience, what is the likely internal diameter of the clay pipe? Was it standard in the 1930's?
- Is there a clever way to make sure I will not break to clay pipe while cutting the top with the angle grinder?
- Do you think that the solution described above is right or there is a better way to do it? better alternatives to mcalpine?
- How to make sure that the seal between the clay pipe and the plastic connector is perfect? would you add silicone or any other type of sealant?

Any advice is greatly appreciated.

Many thanks!

Tony

 

[JCplumb]

It's not easy breaking thre old mortar out, risky too but if you need to do it, then you need to do it. One way is to drill a lot of the mortar out, then carefully tap at the loose or broken mortar being careful not to hit the clay until you free chunks of it up. You need to put something down the pipe to catch anything that drops down there while doing this.
You'll probably find the diameter is 4'' under the mortar, then you just need a clay to PVC socket which you can cement in depending on the socket you're likely to need a short piece of 110 pipe in the top so your pan connector fits.
I haven't done this often but when I have I used a socket with a lip on the section that goes into the clay, helps stop it coming loose if you need to pull the 110 back out. If you google 'clay to PVC socket' you'll see what I mean.

 

[Anto74]

Thanks JC. This is very helpful. Good idea to drill the mortar in multiple location.

When you did this in the past, did keep only the 4'' pipe and broke the wider section which is above the floor? if yes did you brake it or cut it?

Many thanks,

Antoine

 

[JCplumb]

I have managed to keep the flanged part all but 1 time, that was a twitchy bum moment when it cracked, luckily it came off really neatly leaving an almost perfect 4'' pipe at floor level the adapter I had seemed a bit weak just propped in the pipe so I useed a McAlpine DC1 adapter instead.

 

[oz-plumber]

You will most probably find the internal diameter of the clay pipe is the same as PVC pipe.

I would cut the clay pipe spigot off at floor level, being very careful not the crack or damage the clay pipe.

The swan neck adaptor will come with a rubber sealing sleeve, with ribs, that should fit inside the clay pipe and seal the connection.

All this sort of work requires experience, if you don't have it, you could end up with a disaster.

Is the floor concrete?
Is there any way of redoing the pipe in PVC to outside the room?

 

[Anto74]

Hi OZ

Thank you for your advice. The floor in concrete and there is no easy way to redoing the pipe in PVC as it would involved breaking a large concrete slab outside the house.

You advice to use directly a swan neck connector is good as I was thinking to use two connectors, as described in my original post.

This is indeed a bit daunting as I have no experience working with old clay pipes and the result might be a disaster if I am not extra careful.

Instead of an angle grinder, which may be too powerful, I was thinking to use a Dremel or my multitool with the diamond cutter. If I come from the inside of the pipe it would put less pressure and would reduce the risk of breaking the pipe?

 

[NickH]

You will never ever be able to cut that with a Dremel or multi tool. A 4" grinder with a diamond blade will struggle a it but will do it. You should aim to cut the bigger flange off and leave just the end of the pipe. Cut through the the old porcelain spigot first and get it out of the way. You will need to cut it from various sides and angles to get through it.
Then cut down vertically though the mortar and flange about every inch or so and then break the bits out as you go. The flange invariably snaps off neatly at the top of the pipe.

 

[Anto74]

Thanks Nick

 

[Anto74]

Hi Nick, I used the process you described above and it worked perfectly (see picture below). I never had the impression that I will break the clay pipe. Thanks again for all the responses.

Tony

 

[NickH]

Well done mate, glad it worked out alright.