Are you sure?...access fitting @ base of stack is a fixed point is it not?...possibly what you should of advised would be to knock out the pipe entry stops to coupling in order to be used as a slip..
It makes no odds unless replacing the complete SVP from top to bottom , unless of course the stack is being picked up on a horizontal part of drain...... Or possibly wet side of stack uses fittings in order for change of direction but of course we know this to be a no no.
Depends if the section of the stack above where you want to break in can be moved upwards. I've sometimes managed to twist the vent section out, then worked from there.
The only place a slip might be needed is to pick up the stack section above the new branch - as I pointed out to the OP way back. Depends on how the SVP/stack is configured at high level
I think you're comparing apples and pears. The OP has a single stack/SVP with a redundant branch. He is putting a new branch into the stack. A different scenario from the photo you have posted.
Out of interest, in your second photo is there a reason for taking the highest waste across to the RH stack rather than the short route to the LH stack?
I was pointing out that you failed to mention a slip coupling 'may' be required..... Ok you forgot to advise the OP but no big deal..
Regarding the stacks in the picture....These were installed 30 odd years ago and since then the house has been completely refurbed along with bathrooms located in different places throughout the house (7 bathrooms) , the 3 stacks you see have recently been modified with some of the original branches/boss pipes in original position.... In all there are 6 stacks.
Out of interest, in your second photo is there a reason for taking the highest waste across to the RH stack rather than the short route to the LH stack?
The LH stack was the original lead ( you can see where the original lead fixings were on wall) which I ripped out and replaced in order to fit the two branches you can see in picture , the RH stack is original although I extended the 2" waste about a meter due to the repositioning of bath.... These waste runs are void of any self/induced syphonage..
...some may wonder why I get the hump when I see shoddy work on this forum...
Why two stacks instead of one? Surely one could have been made redundant to help the aesthetics of the building?
And why does the waste travel the long distance to the right hand stack instead of the short distance to the left hand one?
Though if the left hand stack was removed the long waste run would still be there unless it was piped inside the building closer to the right hand side?
Also why is the WC branch ventilated when it looks within the 6m maximum distance of the primary ventilated stack as specified by building control?
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