new bathroom DWV design
#1
08-30-15, 08:09 PM
new bathroom DWV design
Many thanks to everybody here who's provided input into this design so far. Here's the plan I'm getting ready to submit with my permit application. I'd greatly appreciate comments. I also have some questions at the end.
The bathroom I'm designing will fit in a closet that measures 13' x 50". The tub is 48", and there's a 9" tiled bench running along the short wall. Vanity is a standard 48"x18". Toilet might end up being a 10" rough-in if it buys me 2" in front. The wall behind the vanity is attic space.
The drain pipes in the floor are shown in the image below. I have 2x8 floor joists. I'm planning to use the following PVC sizes:
vanity to 1st wye: 1.5"
tub to 1st wye: 1.5"
1st wye to 2nd wye: 2"
toilet back to stack: 3"
all re-vent pipes: 1.5" except for the pipe that goes through the roof, which will be 2"
The horizontal run of 3" PVC from the toilet flange to the stack is shown below. (Note that the image is now rotated 90-degrees from previous images.) The total length is 20-feet. The 3" PVC has a slope of 1/8" per foot to comply with IPC 2012. This allows me to stay within the 2x8 cavity until I reach a 2x12 beam (at a distance of 10-feet from the toilet flange). At that point, the 3" PVC will start to dip below the ceiling, which is ok.
The image below shows in more detail how the 3" PVC will drop below the ceiling before entering the stack. Am I allowed to make connections like this?
The re-vent pipe for the tub is tricky. I'm running a 1.5" pipe through the void space under the bench next to the tub. Is this ok? I can't drill through the joists in this area because the hole would have to be closer than 2" to the edge of the joist.
Some additional questions:
- Where do I need clean-outs?
- Directly below the new bathroom is my hot water heater, and there's a gas supply pipe that runs in the same 2x8 cavity as the vanity waste pipe. Are there any rules that prohibit me from running gas and waste in the same 2x8 cavity?
- I'm planning to use a 4x3 90-degree spigot for the toilet waste pipe. I suspect the spigot will extend past the finished floor. Is it ok to trim the spigot to be flush with the finished floor before installing the flange? If not, what's the solution if my flange sits too high? I can't drop the waste line any lower because of the 2x12 beam.
Thank you!
The bathroom I'm designing will fit in a closet that measures 13' x 50". The tub is 48", and there's a 9" tiled bench running along the short wall. Vanity is a standard 48"x18". Toilet might end up being a 10" rough-in if it buys me 2" in front. The wall behind the vanity is attic space.
The drain pipes in the floor are shown in the image below. I have 2x8 floor joists. I'm planning to use the following PVC sizes:
vanity to 1st wye: 1.5"
tub to 1st wye: 1.5"
1st wye to 2nd wye: 2"
toilet back to stack: 3"
all re-vent pipes: 1.5" except for the pipe that goes through the roof, which will be 2"
The horizontal run of 3" PVC from the toilet flange to the stack is shown below. (Note that the image is now rotated 90-degrees from previous images.) The total length is 20-feet. The 3" PVC has a slope of 1/8" per foot to comply with IPC 2012. This allows me to stay within the 2x8 cavity until I reach a 2x12 beam (at a distance of 10-feet from the toilet flange). At that point, the 3" PVC will start to dip below the ceiling, which is ok.
The image below shows in more detail how the 3" PVC will drop below the ceiling before entering the stack. Am I allowed to make connections like this?
The re-vent pipe for the tub is tricky. I'm running a 1.5" pipe through the void space under the bench next to the tub. Is this ok? I can't drill through the joists in this area because the hole would have to be closer than 2" to the edge of the joist.
Some additional questions:
- Where do I need clean-outs?
- Directly below the new bathroom is my hot water heater, and there's a gas supply pipe that runs in the same 2x8 cavity as the vanity waste pipe. Are there any rules that prohibit me from running gas and waste in the same 2x8 cavity?
- I'm planning to use a 4x3 90-degree spigot for the toilet waste pipe. I suspect the spigot will extend past the finished floor. Is it ok to trim the spigot to be flush with the finished floor before installing the flange? If not, what's the solution if my flange sits too high? I can't drop the waste line any lower because of the 2x12 beam.
Thank you!
#2
08-31-15, 10:26 AM
Overall it looks good, and very nice drawings!
A few comments:
- The vent from the toilet up through the roof needs to be 2". (The bath and vanity need 1.5" as you have planned). In the way you currently have it drawn, I think that means your sink drain and vent would need to be 2" too, which is overkill. Can your toilet vent go straight (or almost) straight up and the sink and shower would join together and into the 2" toilet vent?
- I believe you can get away without the bath vent if the distance between the shower trap and the sink wye is less than 5'. You are allowed to use the sink as a wet-vent.
- You mention switching to 2" pipe after the sink drain. The sink and bath can both use a single 1.5" drain until it hits the 3" main drain.
- Your connection to the main stack looks good. You need to use a combo wye, which is what you have drawn.
- As for the toilet flange, you should be able to get a 3" street flange, that goes into the 3" 90deg elbow. I think you'll be fine in the 2x8 cavity. Also remember to figure in what kind of flooring you'll be using. If you're tiling, you'll probably be adding another 1.5" or so in floor thickness which you can use to your advantage.
- And no issue with gas and plumbing pipes in the same cavity.
Hope this helps!
A few comments:
- The vent from the toilet up through the roof needs to be 2". (The bath and vanity need 1.5" as you have planned). In the way you currently have it drawn, I think that means your sink drain and vent would need to be 2" too, which is overkill. Can your toilet vent go straight (or almost) straight up and the sink and shower would join together and into the 2" toilet vent?
- I believe you can get away without the bath vent if the distance between the shower trap and the sink wye is less than 5'. You are allowed to use the sink as a wet-vent.
- You mention switching to 2" pipe after the sink drain. The sink and bath can both use a single 1.5" drain until it hits the 3" main drain.
- Your connection to the main stack looks good. You need to use a combo wye, which is what you have drawn.
- As for the toilet flange, you should be able to get a 3" street flange, that goes into the 3" 90deg elbow. I think you'll be fine in the 2x8 cavity. Also remember to figure in what kind of flooring you'll be using. If you're tiling, you'll probably be adding another 1.5" or so in floor thickness which you can use to your advantage.
- And no issue with gas and plumbing pipes in the same cavity.
Hope this helps!
#5
08-31-15, 11:56 AM
Zorfdt,
Thank you very much for the comments! Some follow-up questions, mostly related to how I should be interpreting code:
- I will increase the vent from the toilet to 2" and run that through the roof as you suggest. That makes more sense to me anyway. I get very confused reading the codes sometimes. Can you explain what this table is referring to?
- Regarding wet-vents, are you saying that the "vent fitting" would be the wye connecting to my sink drain? Does the length of the branch from the wye back to the sink play any part in the calculation at all when I'm looking at venting the tub?
- Another question regarding the wet vent idea: if I use the sink as a wet vent for the tub, does this table mean I have to increase the pipe size from the sink to 2"?
- Thanks for catching that I can use a 1.5" pipe all the way back to the 3" drain. I confirmed that meet my code. That's going to make it easier to drill through my joists.
- Regarding the flange, is it not common to use a 4x3 elbow? Seems like that would give me some flexibility if I need to trim it. If not, I'll stick with the regular 3" elbow, but I'm nervous about being too high in the end.
Again, thank you very much for your help!
Thank you very much for the comments! Some follow-up questions, mostly related to how I should be interpreting code:
- I will increase the vent from the toilet to 2" and run that through the roof as you suggest. That makes more sense to me anyway. I get very confused reading the codes sometimes. Can you explain what this table is referring to?
- Regarding wet-vents, are you saying that the "vent fitting" would be the wye connecting to my sink drain? Does the length of the branch from the wye back to the sink play any part in the calculation at all when I'm looking at venting the tub?
- Another question regarding the wet vent idea: if I use the sink as a wet vent for the tub, does this table mean I have to increase the pipe size from the sink to 2"?
- Thanks for catching that I can use a 1.5" pipe all the way back to the 3" drain. I confirmed that meet my code. That's going to make it easier to drill through my joists.
- Regarding the flange, is it not common to use a 4x3 elbow? Seems like that would give me some flexibility if I need to trim it. If not, I'll stick with the regular 3" elbow, but I'm nervous about being too high in the end.
Again, thank you very much for your help!
#6
08-31-15, 01:44 PM
Super Moderator
The toilet line to the stack make 3"
The sink vent will act as the vent for the toilet and that additional vent you show is not needed.
Use an inside glue flange that goes inside a 3" elbow. ( If you need maximum height use a 3" st ell and a flange that glues on the st side of the ell..
Install a 3x3x2 Y to the sink. From toilet to sink san tee in wall should all be 2". Coming off the san tee on top you can reduce to 1 1/2 for the vent through the roof.
On the 2" sink line in the floor install a 2x2x1 1/2" Y for the tub. No vent needed if tub is with in 6 ft of the Y. If its more then 6 ft increase tub line to 2" to gain you 8 ft to the Y.
Chapter 9 - Vents
The sink vent will act as the vent for the toilet and that additional vent you show is not needed.
Use an inside glue flange that goes inside a 3" elbow. ( If you need maximum height use a 3" st ell and a flange that glues on the st side of the ell..
Install a 3x3x2 Y to the sink. From toilet to sink san tee in wall should all be 2". Coming off the san tee on top you can reduce to 1 1/2 for the vent through the roof.
On the 2" sink line in the floor install a 2x2x1 1/2" Y for the tub. No vent needed if tub is with in 6 ft of the Y. If its more then 6 ft increase tub line to 2" to gain you 8 ft to the Y.
Chapter 9 - Vents
#8
08-31-15, 02:38 PM
Wow, that really simplifies my vent design.
So that I can explain this to my code inspector, let me be sure I understand:
1. When you say that no vent is needed to the tub if it is within 6ft of the wye, you're talking about the wye connecting the 1.5" pipe to the 2" pipe, correct?
Can you explain what this section of the code is telling me? I just don't get it.
2. Table 912.3 in the codebook shows the wet vent pipe size per DFU. Is this the right table to use to determine the size of pipe back to the sink? It seems the DFU on the wet vent in my case is the toilet (3) + tub (2) = 5. So why don't I need a 2.5" drain pipe from the wye to the sink?
Thanks a lot for your help!
So that I can explain this to my code inspector, let me be sure I understand:
1. When you say that no vent is needed to the tub if it is within 6ft of the wye, you're talking about the wye connecting the 1.5" pipe to the 2" pipe, correct?
Can you explain what this section of the code is telling me? I just don't get it.
912.1 Horizontal wet vent permitted.
Any combination of fixtures within two bathroom groups located on the same floor level is permitted to be vented by a horizontal wet vent. The wet vent shall be considered the vent for the fixtures and shall extend from the connection of the dry vent along the direction of the flow in the drain pipe to the most downstream fixture drain connection to the horizontal branch drain. Each wet-vented fixture drain shall connect independently to the horizontal wet vent. Only the fixtures within the bathroom groups shall connect to the wet-vented horizontal branch drain. Any additional fixtures shall discharge downstream of the horizontal wet vent.
Any combination of fixtures within two bathroom groups located on the same floor level is permitted to be vented by a horizontal wet vent. The wet vent shall be considered the vent for the fixtures and shall extend from the connection of the dry vent along the direction of the flow in the drain pipe to the most downstream fixture drain connection to the horizontal branch drain. Each wet-vented fixture drain shall connect independently to the horizontal wet vent. Only the fixtures within the bathroom groups shall connect to the wet-vented horizontal branch drain. Any additional fixtures shall discharge downstream of the horizontal wet vent.
Thanks a lot for your help!
#9
08-31-15, 03:25 PM
Attempting to answer my own question #2 here:
I think I was interpreting 912.3 backwards. The wet vent for the toilet is DFU=sink+tub=3. So that's a 2" pipe back to the wye. But the wet vent for the tub is just DFU=sink=1. So why couldn't I use a 1.5" pipe from the wye back to the sink?
I think I was interpreting 912.3 backwards. The wet vent for the toilet is DFU=sink+tub=3. So that's a 2" pipe back to the wye. But the wet vent for the tub is just DFU=sink=1. So why couldn't I use a 1.5" pipe from the wye back to the sink?
#10
08-31-15, 04:04 PM
Super Moderator
1. When you say that no vent is needed to the tub if it is within 6ft of the wye, you're talking about the wye connecting the 1.5" pipe to the 2" pipe, correct?
Can you explain what this section of the code is telling me? I just don't get it.
Any combination of fixtures within two bathroom groups located on the same floor level is permitted to be vented by a horizontal wet vent. The wet vent shall be considered the vent for the fixtures and shall extend from the connection of the dry vent along the direction of the flow in the drain pipe to the most downstream fixture drain connection to the horizontal branch drain. Each wet-vented fixture drain shall connect independently to the horizontal wet vent. Only the fixtures within the bathroom groups shall connect to the wet-vented horizontal branch drain. Any additional fixtures shall discharge downstream of the horizontal wet vent.
Example if you tied the tub separately to the 3" line then a separate vent as you show would be required..
2. Table 912.3 in the codebook shows the wet vent pipe size per DFU. Is this the right table to use to determine the size of pipe back to the sink? It seems the DFU on the wet vent in my case is the toilet (3) + tub (2) = 5. So why don't I need a 2.5" drain pipe from the wye to the sink?
912.3 Size.
The dry vent serving the wet vent shall be sized based on the largest required diameter of pipe within the wet-vent system served by the dry vent. The wet vent shall be of a size not less than that specified in Table 912.3, based on the fixture unit discharge to the wet vent.
Ill have to look into that to give you the answer why. IMO you dont count the toilet only the items flowing into the 2" line which is the tub and sink. Says 4 fixture units. Sink is 1 I believe and tub is 3?
Its been a while for me to cite code. I just know how to pipe it in my head..
If I ever had to get my plumbing license @ 49 years old I would probably fail it horribly. I can pipe it in my head but sometimes cant explain why...
#11
08-31-15, 04:10 PM
Super Moderator
Attempting to answer my own question #2 here:
I think I was interpreting 912.3 backwards. The wet vent for the toilet is DFU=sink+tub=3. So that's a 2" pipe back to the wye. But the wet vent for the tub is just DFU=sink=1. So why couldn't I use a 1.5" pipe from the wye back to the sink?
I think I was interpreting 912.3 backwards. The wet vent for the toilet is DFU=sink+tub=3. So that's a 2" pipe back to the wye. But the wet vent for the tub is just DFU=sink=1. So why couldn't I use a 1.5" pipe from the wye back to the sink?
If you think of the reason for this is because who has a 2x 1 1/2 x 1 1/2 Y on thier truck.
Just carry 2 " y's and simplify.
2x2x 1 1/2 are more of a standard to carry for the tub..
Otherwise you need to carry bushings.
But what I said below about the tub and sink is the reason..
#12
08-31-15, 05:48 PM
Fantastic! I can't thank you enough... you have saved me a ton of work running unnecessary re-vent pipes! I know exactly what you mean about using what you have available. There's no good reason not to run 2" pipe to the sink.
Now that I'm home I can check distances on my 3D model, and I see that the length of pipe from the tub trap to the wye is 6'4". So I'll need to make that a 2" pipe if I'm going to use the sink drain as a wet vent. Or maybe I could just reverse it and make the tub the dry vent, right? I haven't searched very hard, but I'm concerned about fitting a 2" p-trap in a 2x8 cavity.
The wall that the tub drain is on is in a section of the attic in which I have access to the cast iron stack from the other upstairs bath. Could I run a vent pipe into the attic and tie into that stack? That may be way more effort than just punching a new hole in the roof, but I'd like to know if it's an option.
Now that I'm home I can check distances on my 3D model, and I see that the length of pipe from the tub trap to the wye is 6'4". So I'll need to make that a 2" pipe if I'm going to use the sink drain as a wet vent. Or maybe I could just reverse it and make the tub the dry vent, right? I haven't searched very hard, but I'm concerned about fitting a 2" p-trap in a 2x8 cavity.
The wall that the tub drain is on is in a section of the attic in which I have access to the cast iron stack from the other upstairs bath. Could I run a vent pipe into the attic and tie into that stack? That may be way more effort than just punching a new hole in the roof, but I'd like to know if it's an option.
#13
08-31-15, 06:17 PM
Super Moderator
and I see that the length of pipe from the tub trap to the wye is 6'4". So I'll need to make that a 2" pipe if I'm going to use the sink drain as a wet vent. Or maybe I could just reverse it and make the tub the dry vent, right? I haven't searched very hard, but I'm concerned about fitting a 2" p-trap in a 2x8 cavity.
Show the inspectoes your plan and post back. When you submit for the permit they will approve or not..
Dont worry..; But let us know
Could I run a vent pipe into the attic and tie into that stack?
