connecting branch to soil stack

elmsoft · 9 Jan 2015

[GALLERY=media, 87926][/GALLERY]

I intend to install a downstairs WC and connect it to the left hand soil stack. There seems to be an opinion on the web as a whole that the best bet is to renew the whole stack in plastic, which seems a lot of work.
What sort of job is branching in cast iron?
I would be grateful for any advice.

Nige F · 9 Jan 2015

You`ve got a real -old skool setup there Soil stack /waste stack /rainwater .To me from the pic. your soil looks like it`s smaller than 4 inch

That could be a problem branching off it .

elmsoft · 9 Jan 2015

Yeah. Wondered why separate stacks for soil and waste- but never occurred to me that the soil might be less than 4" . Didn't even know that less than 4" or 110 mm existed!
So that's valuable insight right there! Thank you.
I'll dig out a tape measure and if it is less than 4" I know the route to take.

Hugh Jaleak · 9 Jan 2015

Personally I'd look to going straight underground with the new WC branch once you're through the wall, connecting into cast can be a ball ache, and bear in mind before doing anything to it, how is the existing cast supported? Cutting through at the base, and removing a section, (even after you've grafted in a plastic junction), still leaves a hell of a lot of weight above that point, if it falls it could kill someone!

Apart from a bit of digging the underground stuff is easy enough to deal with and has the advantage it wont fall on your head....

Groovejet · 9 Jan 2015

No problem

Old school set up

Its a propper job....Waste into soil stack, and grey water and rainwater into drain.

Materials needed would be-
110 x 4" plastic to cast connectors - x2 Or 1 slip socket and 1 cast to plastic socket (metric to imperial)
110mm soil tee x1
110 soil pipe
soil pipe clips x3 or 4

N.B- Because the cast pipe is rigid and its not easily removed from original brackets to cut, a slip socket allows you to connect a tee into stack and then slide the slip socket back down the pipe to make final connection.
Thus not having to lift out the top section and drop it back in place...Which would be very hard.

Job-
Connect the Tee and two sockets up using short lenths of 110mm pipe (Top & Bottom connections)

Offer up the fitting to the stack, where its final position will be and mark top and bottom , making sure the correct amount of cast pipe will be left to insert into fittings

Using a 9"grinder cut into stack at marked position

Make sure stack is secure and cut second mark, so that a section is now cut out.

Using the 110x4" slip socket first....push on stack so it slides past the end so its out the way for the moment , letting us get the tee and 2nd socket on easily.

lubricate and push on Tee and socket that was made up earlier

Now align slip socket with tee and pull/push slip socket onto tee. Vetical section complete.

Install horrizontal pipe into tee

Secure with new clips

Connect up new wc etc........

p.s- Alot of the time the elbow connecting existing w/c was cast iron x lead, this means the 'making good', of the area around pipe in the bathroom will be needed i.e patched up with brick and mortar when you end up knocking a big hole aroung the pipe to get it out

elmsoft · 10 Jan 2015

Wow!!
You clearly know your stuff.
Many thanks for taking so much trouble to help.
What a detailed reply

elmsoft · 10 Jan 2015

Hugh Jaleak said:
Personally I'd look to going straight underground with the new WC branch once you're through the wall, connecting into cast can be a ball ache, and bear in mind before doing anything to it, how is the existing cast supported? Cutting through at the base, and removing a section, (even after you've grafted in a plastic junction), still leaves a hell of a lot of weight above that point, if it falls it could kill someone!

Apart from a bit of digging the underground stuff is easy enough to deal with and has the advantage it wont fall on your head....

If I tap directly into the underground drain do I need to vent it- ie run a vertical stack?

Nige F · 10 Jan 2015

No ,it's already vented - sorry I didn't give you a propper answer before

elmsoft · 10 Jan 2015

That gives me three good options!!
Always better to have to choose a solution than not having one

Thanks guys. Much appreciated.

Groovejet · 12 Jan 2015

yeh i agree, everyones input valued

Hugh Jaleak · 12 Jan 2015

Just to add to previous advice, a W.C. is allowed to be directly connected to the drain provided the depth from the crown (top) of the WC trap to the invert (bottom edge) of the drain is less than 1.3m, anything deeper needs a stub stack arrangement. (Unlikely I would imagine in your case.)

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connecting branch to soil stack

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