Soil stacks

[Cgas]

hi all,
In regards to regs I have two stacks in my house. One looks like this;

Goes straight into the toilet, and downwards it disappears into ground and into drains.

The other is a full height stack with an open vent.
Question is I'm renovating and just got to this second bathroom, can I just run it straight into the bog or does this have to be an open vent too? or is there no need ? I thought u only needed an open vent every 4-5 houses ? any help appreciated!
Cheers
Cgas.

 

[polesapart]

Should be OK if on ground floor. After all the existing worked, did it not?

An alternative is the stub stack i.e. a branch in place of the access bend pictured with a short bit of pipe terminating in an access cap just above the height of the w.c. pan.

 

[Cgas]

Should be OK if on ground floor. After all the existing worked, did it not?

An alternative is the stub stack i.e. a branch in place of the access bend pictured with a short bit of pipe terminating in an access cap just above the height of the w.c. pan.

True the existing did work. The house is split level so it's hard to explain. It's ground level for that side of the house but we have a void under the floor, the previous owners literally bodged everything so I'm planning to cut the stack in the void and start again, but I don't want to run it through the roof just to vent, and seeing how they've done it I am just curious if it will be a problem ?