Connecting waste pipes onto soil pipes (top or side feed?)

[STEVEROG]

Where should plastic waste pipes (from say shower or basins etc) be connected to the soil pipe. Should I feed into the top of the soil pipe or into the side? For example, if I have a soil pipe running horizontally (with the slight fall that is needed) I could run my shower waste pipe (with fall) to this and feed straight in to the side (just slightly higher than the middle of the soil pipe if your looking down the soil pipe). The other option is to run my shower waste pipe so it ends up just above the top of the soil pipe then add a couple of 45 bends and then feed into the the soil pipe at almost the top of the soil pipe. I believe that the 'top feed' might be bettter as maybe there is less chance of syphoning?

Any regs on this or any thoughts?

 

[Bahco]

Do you have a low soil pipe or is it a sub stack

 

[STEVEROG]

Not sure what you mean by "low soil pipe" and "sub stack". I will try to explain what the soil pipe installation is like and you can hopefully tell me what I have.....

Inside my 1930's bungalow, we have a soil pipe running under the floor (buried in pea shingle) just off horizonal (regulation slope I assume) from around the centre of the bungalow to the drain outside in the alleyway. The other end of this pipe connects to a vertical plastic pipe that runs right through the bungalow and out of the roof. I assume this is the "soil stack". A toilet connects to the soil pipe very close to the stack, not sure exactly where and how (I have not looked). The only other connections to the system are to the horizontal soil pipe (buried in the pea shingle under the floor) which are a feed in to the top of this pipe from the bathroom basin waste and fed in to the side of the this pipe from the bath waste. So there are both side feed and top feed. I just wondered which was preferred and why. Maybe it does not matter?

Hope that helps

Steve

 

[seco services]

these connections from the basin,bath into the horizontal pipe have they been added later or original ?

 

[STEVEROG]

I am not sure, however, my best guess is that this was all done in one hit as the bungalow was renovated in the 80's long before I purchased it. At this time the one bathroom that existed was moved to a new location in the building (where it is now). Given that there is still only this one bathroom with single inputs into the soil pipe for basin waste, toilet waste and bath waste it must have all been done at the same time! However, this does not mean it was done correctly. Given how much botched work I have found in the property it would not suprise me if this is also sub-standard work!

 

[seco services]

that is the reason i asked cause the joins should be into the vertical stack not the horizontal.
on your property the first join into a stack pipe must be no lower than 450mm from the drain invert level.

 

[STEVEROG]

So it looks like the whole installation is incorrect, that's just great!!!!

Not sure what you mean by "drain invert level" can you explain?

Fortunately I want to rip out and re-fit the existing bathroom so when I come to do this I can try to put the botched up work right. I think it should be possible to get the 450mm distance for the basin waste - I am assuming the 450mm distance is measured from the point where the basin waste pipe enters the vertical stack down to the point where the horizontal soil pipe enters the stack (is that correct?). However, not sure about the toilet and bath as these are obviously sitting at a much lower height than the basin. I will need to take some measurements and see exactly what the distance is between floor level and the horizonal soil pipe entry to the vertical stack. I don't think this is going to be much more than a foot below the floor height. What are my options if this is the case with regard to the toilet and bath waste?

 

[STEVEROG]

Regarding the "drain invert level" you referred to. Is this:-

(a) The lowest level of the outgoing pipe I can see when I look into the manhole in my alleyway at the side of my house? This manhole is about a foot from the side of the building and the horizontal soil pipe feeds into this chamber just above the outgoing pipe.

(b) Something else?

Once I know I will try to determine the height that I have to work with inside my bathroom based on the 450mm limit you spoke of.

 

[seco services]

useally on a first floor bathroom by the time the floorboards are down and the toilet waste joins the stack is is just over 450-500mm

 

[kjacko]

I asked this very question to a plumber this morning. He told me if connecting into a horizontal soil pipe then go in on the top only at approx 90°.
I'm connecting my en suite sink this way. Soil stack is too high to connect the bath waste into the top of it so i'll have to tee into the existing bath waste in the other bathroom.

 

[EViS]

Apologies for interrupting the thread but what is the reason for the 'no connections below 450mm rule'?