Bathroom planning advice (venting questions primarily)

[dayster]

Hi folks, I am long time reader/lurker on this great site.

I am planning a bathroom reno that will include a tub, separate shower, WC, and sink (nothing innovative there!) All piping will be new. The bathroom is above my kitchen, and i am aiming to maximize kitchen ceiling height, so have planned the fixture branches to all run "west" between the floor joists to a "north-south" oriented main drain line which then hooks into the stack. I will need to build a chase in the kitchen ceiling to conceal this main drain line.

Anyhow - i am attaching a bathroom floorplan and my planned drain and vent plan. I have two key questions:

1 - the toilet is 7ft from the stack. does it need any venting of its own? I think its OK without.
2 - the tub drain would be about 4ft from the stack - does it need any venting of its own? I suspect it does, because having the toilet drain past could siphon the tub p-trap.

Location is Vancouver BC if that matters. Bldg department told me that there is nothing in the code that says the stack cannot be outside the building (and I checked the code and agree). The current stack is on the outside, I plan to remove that one and install the new one I show on the drawings.

Thank you for your assistance all!

http://imgur.com/gjqse5c
http://imgur.com/9YMw3bn

 

[Stuff]

Toilet is wet vented by lav drain so should be fine as long as upsized to 2".

Shower and tub have horizontal dry vents under floor which is bad. Maybe take shower to the right to catch vent. Then circle back to tub?

Assume 1st floor and basement are vented separately.

 

[Sponsor]

 

[dayster]

Thanks Stuff.

I presume the horizontal dry vents are bad because they are subject to clogging if they get backed up? That said, are they typically allowed? I'm loathe to drill the joists to take either vent in a direction perpendicular to the joists, as they are only 2x8s.

Yes 1st floor and basement are vented separately.

 

[Stuff]

BC may have different rules but horizontal dry vents are not allowed in most places below the flood level of the fixtures served.

According to your diagram you are already putting holes in the joists for the dry vents. This would be routing the drain through the same holes just upsized to 2". May need a cleanout, though.

 

[dayster]

I wasn't intending to put holes in the joints for the dry vents, I was intending to keep each P-trap and its corresponding vent within the same joist bay. But I see how you could read my diagram that way.

I have attached a revised drawing, with revisions to the tub and shower venting:

http://imgur.com/4EN45BR

Shower - move the drain and dry vent such that there's little or no horizontal dry vent. Still not sure that all this can fit without protruding below the bottom of the joists. If it can't then I may take the shower drain the opposite direction and install a vertical drain to the basement with vent above in the wall to the right (basically a dead standard approach i think).

Tub - use a 3x3x2 San Tee with a 2" or 1/2" inlet. Use the inlet to vent upwards. The only thing about this is that the vent will be venting the 3" branch line as much as it is venting the tub line - but I would think that should not matter, what matters is that the air is available so the tub's P trap doesn't siphon.

http://www.supplyhouse.com/Nibco-I4...-Hub-ABS-Sanitary-Tee-with-90-Left-Inlet-5871

What do you think of this? Thanks for helping, it is truly appreciated.

 

[Stuff]

Good idea for tub but normally a san-tee can not be used on its side as the bend is too tight. I don't think they make a combination fitting that does what you need. Probably need a long sweep 90 then a tee-wye for venting and finally a 3x3x2 wye.

"Dead standard approach" for shower sounds like the easiest compliant solution. Also showers are now 2" drains/traps with 1 1/2" vent.

 

[hj]

Is the sink trap under the floor, which is what it looks like? WHERE are you going to find a 3x3x2x1 1/2 tee, even if you were allowed to use it?