Fixtures per 2" vent line

[maintenance man]

I am working on a new construction bath and the circumstances of the walls make running vent lines difficult, I would like to run a double sink, shower, and a separate bath tub all into a single 2" vent line. The toilet would be on a separate vent as it is some distance away. Are those 4 fixtures too much for one 2" vent? Also is there a general limit of distance for a horizontal run of the vent line under the floor to tie them all together?

 

[Jadnashua]

Look up 'fixture units'...it let's you know how much can go down a drain and (if I remember properly) what is needed to vent them. Each fixture has a specific number assigned to it. Also, depending on where you live, the actual vent size may need to be increased before it penetrates the roof to prevent frost from closing it off in the winter.

As to vent lines beneath the floor, essentially, you cannot run a vent below a floor UNLESS it is at least 6" above the flood plane of anything it is serving OR 42" above the floor, whichever is higher. Also, any horizontal runs need at least 1/4"/foot slope so that condensation and potential precipitation can drain down to the normal drain lines.

 

[Sponsor]

 

[hj]

"Running a vent under the floor and tying them together" raises a red flag, because that would require a very specific piping arrangement.