Drainage for downstairs toilet

[flanagaj]

I want to rework the proposed foul drainage for our bathroom as I currently don't like it, but unsure how I handle the WC shown below.  I am not sure whether I could simply run it under ground and into the proposed stack shown in the right hand corner of the plant room, or whether I need another inspection chamber outside and stack for it.  I wasn't sure whether I could have a stub AAV concealed in the unit that boxes in the wall mounted pan frame or whether the stack would have terminate in the attic.  if that is the case then I will need to reduce the width of the window.

The Technical Architect has proposed the below, but I think it looks **** and pushes the tray  out.  I also don't like the door into the bathroom



My proposed solution was the below, but that with the boxed in toilet frame might also look naff.



It was reworked at the last minute as access to the plant room was from outside and this then meant that although the plant room was inside the thermal envelope it apparently isn't treated as such and the walls needed to have 200mm of celotex.  This then made me think that accessing it from the downstairs bathroom made sense.  I did think to have the door in the downstairs playroom, but that is actually a proposed bedroom.

[Big Jimbo]

I would run the waste from both the W.C. and the shower underground, and into the stack, in the corner of the plant room. i doubt you would need an AV for such a short run, but because i don't know any better, i would hide One in the W.C. boxing, with a durco on the top.

[flanagaj]

19 minutes ago, Big Jimbo said:

I would run the waste from both the W.C. and the shower underground, and into the stack, in the corner of the plant room. i doubt you would need an AV for such a short run, but because i don't know any better, i would hide One in the W.C. boxing, with a durco on the top.

I did think of that, but was unsure whether that would meet building regs.

[Nickfromwales]

43 minutes ago, flanagaj said:

I did think of that, but was unsure whether that would meet building regs.

B Regs will tell you that you 100% defo do NOT need an AAV, if the invert is <1300mm from the pan outlet to the bottom of the manhole it connects to.

 

Furthermore, you wouldn't benefit from fitting one anyways, as the long horizontal run is a natural air break; this means no vacuum can occur so no air needs admitting.

[Nickfromwales]

If the WC pipe drops down, and then disappears underground, then you may have to provision for rodding access at the rear of the WC, if the BCO is the most pedantic git on earth. Just tell then the lid to the boxing in is removable and you can rod down there, by using a T with a rodding eye at the outlet of the pan instead of a bend. Then box the lot in and enjoy your life.

[flanagaj]

9 hours ago, Nickfromwales said:

by using a T with a rodding eye at the outlet of the pan instead of a bend.

Are you able to elaborate or show me an example of a connecter?

[Nickfromwales]

14 hours ago, flanagaj said:

Are you able to elaborate or show me an example of a connecter?

 

 

 

WC goes in to the branch, waste drops down. Rodding access goes in the top. 

[flanagaj]

18 minutes ago, Nickfromwales said:

 

 

 

WC goes in to the branch, waste drops down. Rodding access goes in the top. 

Thanks