Soil pipe modification

[Snowyy]

Hi
I'm wanting to fit a new toilet and relocate the soil pipe n the bathroom and after some advice about doing so. The current soil pipe is as shown:

I'm assuming that the pipework is just push fit together and not glued in?

And what we have on the inside is as shown:

The distance from the current soil pipe to the new location will be 1mtr, currently the bath waste runs under the floor board and comes out the wall and connects to the soil pipe. If possible I would like to run the bath waste above the floor board, was thinking a 90 degree pan connector on toilet then a length of pipe and then an elbow to fit from this pipe onto the existing pipe going out the wall. Questions relating to this are
1) what type of elbow fitting would i need as I have seen double socket and single
2) would the elbow have a boss connector etc so that I could run the bath waste into this and do away with the pipework under floorboard going out of the wall
3) Measured the height of the existing pan at roughly 140mm to the bottom, the pan on the new toilet is 130mm to the bottom as shown below, I understand there has to be a fall in the pipe to allow waste to flow away (1:100?). The new toilet will be sat on plywood and vinyl so this will elevate the pan on the toilet even higher so pipe will pretty much be level-should I try to lower the exisitng pan by disconnecting and chiselling wall down 10mm or will it be ok at the current height?

T

Thanks for any advice

 

[Hugh Jaleak]

You need a minimum 1:40 fall on the soil pipework, anything less is just going to give you a headache, especially with small volume flush on new pans. If you must move the pan position, then alter the pipework to suit, although I am struggling to work out where the new pan position would be on the wall externally. If my suspicions are correct, and it's going to be closer to that internal corner, then look at replacing the current 110mm bend with a corner branch, use the additional socket for the WC connection, and stick a blanking cap in the top. Vent will continue as existing.

I would also seriously consider replacing the waste pipework under the floor with solvent welded waste, the last thing you want is that springing a leak, especially if you're plonking a pan on top of it!

 

[Snowyy]

You need a minimum 1:40 fall on the soil pipework, anything less is just going to give you a headache, especially with small volume flush on new pans. If you must move the pan position, then alter the pipework to suit, although I am struggling to work out where the new pan position would be on the wall externally. If my suspicions are correct, and it's going to be closer to that internal corner, then look at replacing the current 110mm bend with a corner branch, use the additional socket for the WC connection, and stick a blanking cap in the top. Vent will continue as existing.

I would also seriously consider replacing the waste pipework under the floor with solvent welded waste, the last thing you want is that springing a leak, especially if you're plonking a pan on top of it!

Thanks Hugh Jaleak, yes initially I was planning on replacing the bend with a branch and going through the wall but then thought about running the pipe from the pan to the existing outlet internally and boxing in. The only issue with that is getting the gradient of 1:40 so it would still require lowering by cutting about 30mm off the vertical external stack and chiselling a bit more of the brickwork out. I thought this would be easier then creating a new hole, replacing the bend with a branch and replacing the existing WC branch with a straight branch, and I've also got to run a 22mm and 15mm copper pipe on that wall so there will be some boxing in and it made sense to include the soil pipe in the boxing in.

 

[Snowyy]

You need a minimum 1:40 fall on the soil pipework, anything less is just going to give you a headache, especially with small volume flush on new pans. If you must move the pan position, then alter the pipework to suit, although I am struggling to work out where the new pan position would be on the wall externally. If my suspicions are correct, and it's going to be closer to that internal corner, then look at replacing the current 110mm bend with a corner branch, use the additional socket for the WC connection, and stick a blanking cap in the top. Vent will continue as existing.

I would also seriously consider replacing the waste pipework under the floor with solvent welded waste, the last thing you want is that springing a leak, especially if you're plonking a pan on top of it!

Also agree with solvent welding basin pipe that is under floor board and to be under the toilet, it needs modifying anyway as it currently has a shower trap on there as well although there was no shower in there when I moved in so who ever ripped it left in the connection.

 

[Hugh Jaleak]

It's your call, but my concern would be going with anything less than 1:40 across that distance, and given it is immediately after leaving the pan, is solid matter could get stuck in the flat section, giving you repeated problems with a blocked toilet. (Seen it several times before, one in fact where they were actually trying to defy the laws of gravity and get sh1t to flow uphill....)

Modern WC's have a smaller (6 litre) flush, and many I'd think are not powerful enough to push the contents of the pan along an almost flat section of pipework immediately afterwards. Personally I'd be looking to get the correct fall, easier to do now than try and alter afterwards.

 

[Snowyy]

It's your call, but my concern would be going with anything less than 1:40 across that distance, and given it is immediately after leaving the pan, is solid matter could get stuck in the flat section, giving you repeated problems with a blocked toilet. (Seen it several times before, one in fact where they were actually trying to defy the laws of gravity and get sh1t to flow uphill....)

Modern WC's have a smaller (6 litre) flush, and many I'd think are not powerful enough to push the contents of the pan along an almost flat section of pipework immediately afterwards. Personally I'd be looking to get the correct fall, easier to do now than try and alter afterwards.

yep get that so if I go for having a horizontal pipe inside boxed would the process be 1) disconnect vertical soil pipe where it goes into the straight coupler and the basin and bath pipes . 2) cut 40mm off the branched section I just removed 3) chisel brickwork where existing pan was 40mm down so that existing pan is now 100mm away from the floor on the inside instead of 140mm it is currently 4) connect pipes back together and slide vertical pipe above the roof down it’s securing clips by 40mm so that decline from existing pan to pipe work outside is still at its initial fall ratio 5) fit pan 90 to toilet and length of pipe from this to current outlet via a bend (single socket?) this should give a fall of min 1:40 as new pan will be 140mm from floor and where it exits will be 100mm and distance is 1mtr. 6) reconnect bath and basin waste to outside branch

Hope all is correct way of doing things, also with no.6 do they sell a 90 bend that would connect soil pipe to the branch/tee that has a boss connect for a bath waste pipe? Seen them on the 90 pan bends, this would allow me to do away with the bath waste under the floor boards. Then I could blank the bath fitting on the external branch and connect the basin one back up

 

[Snowyy]

yep get that so if I go for having a horizontal pipe inside boxed would the process be 1) disconnect vertical soil pipe where it goes into the straight coupler and the basin and bath pipes . 2) cut 40mm off the branched section I just removed 3) chisel brickwork where existing pan was 40mm down so that existing pan is now 100mm away from the floor on the inside instead of 140mm it is currently 4) connect pipes back together and slide vertical pipe above the roof down it’s securing clips by 40mm so that decline from existing pan to pipe work outside is still at its initial fall ratio 5) fit pan 90 to toilet and length of pipe from this to current outlet via a bend (single socket?) this should give a fall of min 1:40 as new pan will be 140mm from floor and where it exits will be 100mm and distance is 1mtr. 6) reconnect bath and basin waste to outside branch

Hope all is correct way of doing things, also with no.6 do they sell a 90 bend that would connect soil pipe to the branch/tee that has a boss connect for a bath waste pipe? Seen them on the 90 pan bends, this would allow me to do away with the bath waste under the floor boards. Then I could blank the bath fitting on the external branch and connect the basin one back up

Anyone else with some advice?