Vertical 110mm junction below a ground floor, allowed?

[epsilonGreedy]

I understand that horizontal drainage junctions below a ground floor are frowned on and require independent external rodding points for each branch.

 

My current drainage planning would be simplified if one drainage pipe could drop down into another as a vertical branch, this would be in the void below a block and beam ground floor.

 

There are two different scenarios:

 

1. Ground floor toilet --> large rest bend --> 2.5m run of 110 pipe @ 1:60 gradient under floor void --> washhand basin drain drops vertically through floor void into 110m pipe --> 110mm pipe continues @1:60 out through cavity footing wall into garden. 
2. Kitchen dishwasher & sink --> rest bend  --> 4.0m run of 110 pipe @ 1:60 gradient under floor void --> soil pipe from en-suit on first floor drops vertically through floor void into 110m pipe --> 110mm pipe continues @1:60 out through cavity footing wall into garden.

 

[Oz07]

Think number one is okay. It's only a basin. I'd have a 110mm branch with pipe coming up thru floor in 110mm. Suppose the rules might be there in case future occupants connected different appliances. 

 

Number 2 id  prefer rest bend bottom of wc with sink and dishwasher connecting into top of this. Same as above connection wise

Edited August 4, 2019 by Oz07

[PeterW]

5 hours ago, epsilonGreedy said:

soil pipe from en-suit on first floor drops vertically through floor void into 110m pipe

 

Definitely not ..!! Will create poo mountain in the lower pipe and you can’t drop a vertical pipe from first floor without a rest bend. 

 

Correct way is a rest bend in the bottom of the 1st floor stack and then run it into a 45 degree Y junction under the floor - pick the most used leg for the main run.