Omitting seperate vent stack

[kvusal]

Dear Experts,
At my project architecture considered small space for shaft of bathroom group waste / soil stack. At this space it is possible to install only one pipe, no space for separate vent stack. What kind of requirement there is to use this waste stack as vent also. (I mean to extend this waste stack upto roof).
Information:
- Building have 15 floor
- Each floor we have 2 bathroom group.

Thanks in advance for recommendations.

 

[Geofd]

Every bathroom group needs a vent to tie into

 

[kvusal]

Dear Geofd, cant we use waste stack as a vent also? Or we need separate stack for vent?

 

[CT18]

If it has waste it is not a vent stack it is a waste stack. You could use it if it had a sink on the floor above. You need a separate vent stack and my area you would need to add a relief vent to that waste stack at every 7 floors I believe it was. I would have to get the current code book to verify. Just imagine using that vented waste stack as a vent if it received waste from toilets. It would not be pretty to have that rolling around the vent lines