new bath drain venting quesion
#1
02-17-21, 02:26 PM
new bath drain venting quesion
I'm going to be adding a drain for a freestanding tub about 3' from an existing shower drain, parallel to the wall where it connects to the sanitary drain. I won't be extending the 2" ABS from the shower drain as the joists run opposite direction. So, I figure I'll run a new 2" drain from tub to the sanitary line in the wall.
I'm still wrapping my head around the varying venting requirements, etc. Any insight on that? I figure I'll have to have the new 2" line vented (I think?), but can I join that new venting to an existing vent in the attic before it heads out the roof? Any good references out there to read up on/watch? Every Ptrap needs a vent right? Thanks!
I'm still wrapping my head around the varying venting requirements, etc. Any insight on that? I figure I'll have to have the new 2" line vented (I think?), but can I join that new venting to an existing vent in the attic before it heads out the roof? Any good references out there to read up on/watch? Every Ptrap needs a vent right? Thanks!
#2
02-18-21, 05:07 AM
Group Moderator
First thing to come to mind is what is the pipe length from your new trap to the existing vent? If it is less than 8' and you properly do 1/4" per foot fall there is a chance the existing vent can be used as the vent for your new fixture.
#3
02-18-21, 11:21 AM
I haven't decided exactly on whether or not to run the new vent pipe in the wall up and then horizontally toward the shower vent which would be about 3-4' and through 3 studs (if that's even an option) or, straight up into attic and then over to the vent going out the roof. If straight up to attic then over, would I measure the entire length? Or just the horizontal distance? If I go into the attic, it's over 8' from the new trap.
Thanks as always!
Thanks as always!
Last edited by sethlit; 02-18-21 at 11:38 AM.
#4
02-19-21, 10:02 AM
Usually bath drains are 1.5". That size pipe allows 6' from the trap to the vent (horizontally). So if you can run the drain pipe from the tub to the wall and into the main stack, and the distance is less than 6', you can use the stack as a vent -- IF there's nothing else draining into the stack above it.
If the drain is longer than 6', has a vertical portion, or connects to the stack where there are fixtures above, you'll need to separately vent it. Usually it's easiest to vent straight up into the attic and back-vent (connect) to the existing vent in the attic. There's more room to work and run the pipe in the attic rather than through studs and connect in a wall.
A sketch or a few pics would probably help confirm everything is planned out correctly.
If the drain is longer than 6', has a vertical portion, or connects to the stack where there are fixtures above, you'll need to separately vent it. Usually it's easiest to vent straight up into the attic and back-vent (connect) to the existing vent in the attic. There's more room to work and run the pipe in the attic rather than through studs and connect in a wall.
A sketch or a few pics would probably help confirm everything is planned out correctly.
#5
02-19-21, 10:09 AM
Group Moderator
It's been mentioned in my and Zorfdt's post. The distance from the trap to vent tie in depends on the size of the pipe. Larger diameter pipes are permitted to run a longer distance before tying into the vent. 1 1/2" is perfectly OK and code approved for a tub (a shower must be 2" minimum) but you can upsize to 2" if you need the extra distance to make it to the vent tie-in.
#6
02-19-21, 10:35 PM
Thanks for both of the replies, very appreciated. I will be able to take some pictures in a few days to give a better view. But just to clarify, if I can run 2" drain pipe from the tub horizontally into wall and reach the stack within 8' (would be more like 4'), then I wouldn't need to add any venting, as the vent that is already in the stack *higher than where my drain would connect) would be suffice?
Side note, I'm installing a freestanding tub, with using the Jucuzzi MZ20000 drain that comes in a 2". And I have a ton of 2" ABS laying around. So I figure, why not run the drain for the tub with 2" pipe anyway. Thanks again
Side note, I'm installing a freestanding tub, with using the Jucuzzi MZ20000 drain that comes in a 2". And I have a ton of 2" ABS laying around. So I figure, why not run the drain for the tub with 2" pipe anyway. Thanks again
