Soil pipe queries - vent stack location, order, distances.

[Richycsurfer]

Hi everyone. Apologies if this isn't the perfect section and it should be in plumbing, I realise it has both regs/plumbing queries.

I'm a new home owner looking to move my bathroom from one side of the house to the other. The current soil system has the vent pipe outside the rear of the house next to the bathroom. The inspection chamber shows 3 branches, one for WC, one for basin in the bathroom and one for sink in the kitchen.

Our plans for the place (rear extension) mean that we will be moving the bathroom to the other side of the house (shown in red outline) and getting rid of the current bathroom. 1) Is it possible to route the 110mm soil pipe as i've shown in the picture below, having the vent stack upstream of the toilet branch (or using a Y connector?). We don't want to keep it at the rear due to the extension we will begin soon meaning we would have to move the vent pipe anyway.

2) Can the new bathroom's shower and basin share this same soil pipe or do i need to run separate 50?mm drainage for them from the new bathroom to the respective branches on the inspection chamber?

I'm unsure of which branch of 3 within the inspection chamber the vent attaches to - will it always be the one with a WC connected or can they be off any to vent the system?

Thanks for any help and guidance.

 

[^woody^]

This work would require building regulation approval - normally on the same application as the extension.

I can't fathom what is happening there from that plan, as to where the new stack can be. But there may be potential options for a stub stack and air admittance valve, or the stack terminating the roof space.

And generally you can't tend to run 100mm soil pipes across a house at first or ground floor levels, due to the practicalities of getting falls and changes in direction.

 

[Richycsurfer]

Thanks for the reply. The house is a bungalow. There is a slope to the site which means there's sufficient space under the floor to get a good fall on the soil pipe.

The blue ring is meant to show the soil vent stack, outside the 'left' of the house. Red ring is the toilet in the (new) downstairs bathroom. The green square shows the location of current inspection hatch which will later require moving further down the garden.

We bought the property with planning approval.

 

[Richycsurfer]

Ah yes sorry. The floor plan shown is pre-extension. I stuck the red around where the new bathroom would be.

 

[oldbutnotdead]

Thanks for the reply. The house is a bungalow. There is a slope to the site which means there's sufficient space under the floor to get a good fall on the soil pipe.

The blue ring is meant to show the soil vent stack, outside the 'left' of the house. Red ring is the toilet in the (new) downstairs bathroom. The green square shows the location of current inspection hatch which will later require moving further down the garden.

We bought the property with planning approval.

Planning permission and building regs are completely different things. You have pp for the work- fab. Before you start you have to tell Building Control what you're doing, they'll tell you whether the details comply.

 

[Richycsurfer]

It's more a case of getting plans together beforehand at the moment.

 

[Richycsurfer]

I've spoken to building control and they say to go ahead with the work but don't cover up the new soil system so it can be inspected. So at this point I suppose I need the plumbing section to ascertain what routing/order I'm allowed by regs and what works practically?

Is the wc allowed to connect lower down on the drain invert than the vertical portion of the vent stack? I see in part H that the lowest connect need be 450mm if on a stack but struggling to find the answer of my question. I see no practical reason it wouldn't be allowed.

Can a vent stack be anywhere in the soil system - just off an inspection chamber for instance? I have seen evidence of this in other build threads but on historic installs.

Finally can all drains (shower/basin) be clamped onto this new soil pipe under the bathroom. Again I see no practical reason why not but it's worth asking since they are currently on separate drains to my I/C.

Thanks!!!

 

[Richycsurfer]

The toilet is going to sit in the bottom right of this picture... The current toilet is behind the wall top left.

I pulled some of the floor in the bathroom and the current toilet has an unvented clay soil pipe straight out the bottom of it, 900mm, then a ~90° turn to the invert which takes it around 3m to the inspection chamber.

Does anyone know if my route above which will introduce a further ~5m of pipe and another 92.5 elbow (I'd cut the clay pipe and attach some plastic with an elbow toward the new bathroom) would be passable by BC?

 

[Richycsurfer]

Crudely phone drawn...