Replace cast iron

[hENRYDAC]

I would like to replace the cast iron branch with plastic but am not sure how far below the floor level I will find the point where the branch spigot enters the female fitting. The floor is in a garage and there is a room below that I cannot access therefore all work has to be done from above. Any advice welcome

 

[centralheatking]

I would like to replace the cast iron branch with plastic but am not sure how far below the floor level I will find the point where the branch spigot enters the female fitting. The floor is in a garage and there is a room below that I cannot access therefore all work has to be done from above. Any advice welcomeView attachment 40768

Hi Henry, does your cast leak ? In my experience mucking about with cast can end up being lots of trouble so be prepared. That is a tight spot and you say there is a void below
what can happen is carrying out your plan can lead to joints separating beyond where you are working even if you are very gentle. Cast is quite unforgiving strong but brittle..there is a lead waste coming in aswell..maybe thats your motivation. see what the others say
centralheatking

 

[hENRYDAC]

Thanks, I need to get a pan connected in there. Luckily there are no connections into the stack above this level so gravity will be my friend. I've already got my eye on the scrap!

 

[snowhead]

You really do need to gain access below for a couple of reasons.

Typically when concrete floors are cast, knowing that pipes will pass through, a larger hole is left which is then patched up after the pipe is installed.
This patching can range anywhere from a couple of paper cement bags or any other rubbish stuffed into the hole and skimmed over, to a full fill with concrete.

This means when working around the filled hole there is a risk that the fill contents may end up in the area below.

Also the fill in the hole may be the only support the pipe below has and once the pipe above is cut the pipe below may drop.
You need to view below to check the pipe has adequate support.

Dedending on the exact floor thickness the joint will be within or part way through the hole below.
Is the smaller cast branch to the right being removed / replaced?

 

[centralheatking]

I can see the vertical coming down and a diaginal from the right h side so the bog is going on the finished floor level in that corner, you have loads to do by the looks of it. Pipes everywhere I like a challenge feel free to ask away on here and extra bogs are worth
£14,000 on house price esp.if its the second one ...this has been my speciality in house renovations over the past 40 years....centralheatking

 

[hENRYDAC]

Thanks chaps, given the warnings about disturbing joints, I'm guessing that making the conversion to 110mm soil would best be done below the concrete floor, sealing externally on the cast, rather than trying to remove the caulk from the socket. This also allows me to set the invert point tight to the finished floor. The customer has set the restriction upon access from below, so, if this is not available, then the risk is on him if he still wants to proceed.

 

[centralheatking]

Good luck HenryDac at least you are going into it eyes open now, let us know how
it ....pans ....out ha ha ...centralheatking

 

[hENRYDAC]

Yes I will. And, ( although you shouldn't begin a sentence with 'and'), thank you for your support.

 

[Deleted member 96286]

Just to add, there will be 150mm or 6 inches in auld money below the branch socket (faucet) of which approximately 100mm or 4 inches will be going into the socket in the floor.
If you carefully break out the branch into the floor, you can chip out the remaining cast iron, lead and rope using a very sharp chisel on the edge of the cast inside the socket. Take your time and it will break away. Stick a bag or a bung down the pipe before breaking out anything as pieces of broken cast iron inside a downpipe are almost impossible to remove.
As it's contained inside a concrete floor, the cast may well be corroded.
If you can get access to the cast below the floor, cut it to a plain end with an angle grinder and join onto it with a timesaver coupling. A timesaver is available as a cast iron to plastic coupling if plastic is what you are intending to use and saves a headache trying to make a watertight seal.
If using plastic between floors, check regs as you may or may not require a fire sleeve.

 

[hENRYDAC]

Thanks again. Should be starting next week hopefully from below the floor.