toilet soil pipe advice?

[johnleddo]

Hello,
I'm installing a ground floor toilet soil pipe into a new extension I'm having built and had a few queries that i'd be very grateful for any advice about, before the pipe work is concealed under a concrete floor!

At the moment I have the 110mm soil pipe running from out side the new extension wall where I will connect it up to a nearby inspection chamber at a later date to an equall T the upright will connect directly to the toilet outlet through the floor with a length of 110mm pipe the other opening continues a further 300mm to a 90degree elbow which will come up through the floor and be fitted with an internal air admittance valve for the sub stack.

I'm wondering if there is anything wrong with this set up? and secondly I have set up all the pipe work so that it has half a bubble of fall on it using my spirit level so I'm wondering if that's enough fall or not? If the toilet soil and sub stack are ok I will also be connecting the sink waste into the sub stack.

any advice or thoughts would be greatly appreciated.
Many thanks
John

 

[Hugh Jaleak]

It sounds ok. The AAV is not entirely necessary, if required you can connect a W.C. directly to the drain provided the drain is no deeper than 1.3m from the bottom of the W.C. outlet. If preferred use a pan connector with a 32mm boss for the basin waste connection. Half a bubble fall should be fine.

 

[johnleddo]

Thanks very much for that info. Does the 1.3m rule comply with building regs? if thats the case I could probably just connect the toilet with a long radius 90 degree bend, which i think the building inspoector will be pleased to see.

Is the 1.3m from the toilet connection to the outlet in the inspection chamber? I would just need to check this height but I suspect I might have a greater height than this.

Having thought about it today I think if I'm required to fit an air admittance valve I might be better off attaching a Y connector to the soil leading to the inspection chamber and connecting a long radius bend to one in let to connect the toilet to and directing the other to the air admittance valve?

Thanks again for your help

 

[Hugh Jaleak]

The 1.3m refers to the height from the bottom of the outlet on the W.C. pan to the invert (bottom of the pipe) in the drain. If the sewer you plan to connect to is fairly deep, then to avoid excessive digging, look at fitting a backdrop outside the manhole. This allows the drain to connect at the right level in the manhole, then run at a shallower depth to the building, whilst still providing rodding access.

May not need a long radius bend, these are usually required at the foot of a soil stack to allow a gradual flow round into the drain. I'd try and avoid putting any 'horizontal' pipework past the W.C. connection to the drain. Should the drain ever block up then you could be left with a 'plug' of waste in this section that may prove difficult to remove.

 

[johnleddo]

Thanks very much excellent advice. good and bad news following today's investigation, good is that I have a lot less that 1.3m between the toilet outlet and the bottom of the drain, in fact it's less than 1m. Could i connect my sink waste into the toilet waste under ground? And if so is it push fit for sink wastes underground connected to a solvent weld collar?

The not so good news is that when I lifted the manhole I found that some concrete from when we poured the founds has found it's way into the drain and probably halved it's size. Everything above the manhole will be replaced with plastic but I don't know what that means for the section between the manhole and the main sewer in the road.

Anyone have any ideas?

 

[Nige F]

Not the end of the world you highlighted a broken drain feeding the old manhole - just install a plastic manhole and risers/lid etc - run it by Build Control first - and use fernco connectors on the pipes

 

[Hugh Jaleak]

Dont see why you cant connect the sink underground, using a boss pipe would be preferable to a strap boss though IMO. I'd use solvent welded pipe underfloor, but make sure you can get a snake through in case you ever need to. (Provide access points as required, keep bends to a minimum and use bends rather than elbows.)

All of the drain that now contains concrete will need to be sorted or you'll have big problems! If you cant get the concrete out then the pipes will have to be replaced.... Upstream isnt an issue but if the concrete has gone further you'll have to replace the affected section, it'll block very quickly otherwise and continue to block. CCTV survey may be wise now to ascertain how much of a problem you've got.