Second Floor Bathroom Remodel

[PBFR20]

I'm in the design process of a remodel of an existing 2nd flr bath/closet. (I'm trying to leave the bathroom functional until I have a good plan established)

This is the existing bath:

As noted this is the second floor and all necessary flooring will be removed when I begin the project.
The existing toilet, vanity, and shower drain through the 3" PVC straight down into the crawlspace.
The 1-1/2" vent behind the vanity exits through the roof above the accessible attic space.

This is the proposed new layout:

The blue marker is the current 1-1/2" vent location (for reference)
The red marker is the location of the 3" waste to the crawlspace.

For additional reference the 2"x8" floor joists (16"o.c.) run longways (left to right), and the 3" drain is ~5" to center off the lower new vanity wall.
It's not noted on the drawing but I plan on building out a wall behind the new vanity location to help with insulation due to recessed wall niches, as well as space for the new plumbing.
Also as you can see the new shower location is larger than a standard shower pan, (again I have not finalized if I'm going with a custom or standard pan), so the location of the drain will be dependent on how the DWV needs to be accomplished.

Here is a pic of the existing waste line going down to the crawlspace:

I have researched this quite a bit and have a general idea of what is needed, (it's been ~18 years since I did my last remodel), but would appreciate some expert help based on current code requirements.

TIA

 

[John Gayewski]

Looks pretty easy to vent each fixture individually to me. Vent in the walls and trap arm to the fixtures. What plumbing code is used in your area? Ipc? Upc?

 

[Sponsor]

 

[PBFR20]

Looks pretty easy to vent each fixture individually to me. Vent in the walls and trap arm to the fixtures. What plumbing code is used in your area? Ipc? Upc?

We follow the IPC.

The original DWV has a single 1-1/2" vent through the roof for all three items.
I was planning to install a 3"x2" combo tee to vent the toilet and sink and use a 3"x2" side inlet (to replace the 3" 90 going to the crawlspace) for the shower drain with a separate vent.
Would that be acceptable practice, and could both vents still use the single roof penetration?

Thanks.

 

[Jeff H Young]

lav center is 4 ft 6 inches to w/c there is a pocket door at toilet room the lav woud vent the toilet. very simply.
the tub seperately vented likly in side wall perhaps remove the 3 inch 90 and replace with a 3 inch low heel outlet to pick up tub with a street 1/4 bend on top . but looks like a pretty basic job like John says.

 

[John Gayewski]

We follow the IPC.

The original DWV has a single 1-1/2" vent through the roof for all three items.
I was planning to install a 3"x2" combo tee to vent the toilet and sink and use a 3"x2" side inlet (to replace the 3" 90 going to the crawlspace) for the shower drain with a separate vent.
Would that be acceptable practice, and could both vents still use the single roof penetration?

Thanks.

I'm assuming there are roof rafters or an attic space where the vents can joint together and then then utilize a single roof penetration?

IPC is slightly different than upc which I'm more familiar with. But your toilet being the farthest upstream poses a problem with sharing a vent with the lav. Especially when there is no elevation to play with. Assuming you don't want to drill out your joists and your very limited on what can be drilled anyway, this makes me want to say you should just vent the fixtures individually and joint them together up in the ceiling where they can combine for a single penetration.

Wayne might jump in with a better idea, but I tend to over vent rather than the minimum. This ensures full flow velocity and zero issues with siphon age.

 

[Jeff H Young]

a 3 inch line with a 3x3x2 combi on its back or 45 can easily legaly continue on for a toilet with out additional vent the combi picks up lav and vents both. very standard practice

 

[PBFR20]

I'm assuming there are roof rafters or an attic space where the vents can joint together and then then utilize a single roof penetration?

IPC is slightly different than upc which I'm more familiar with. But your toilet being the farthest upstream poses a problem with sharing a vent with the lav. Especially when the no elevation to pay with. Assuming you don't want to drill out your joists and your very limited on what can be drilled anyway, this makes me want to say you should just vent the fixtures individually and joint them together up in the ceiling where they can combine for a single penetration.

Wayne might jump in with a better idea, but I tend to over vent rather than the minimum. This ensures full flow velocity and zero issues with siphon age.

Yes, the roof is rafter construction (not truss) with a floating ceiling above the space. I'm removing the existing flat ceiling and going with a vaulted ceiling for more visual space. So connecting the vents shouldn't be an issue.

lav center is 4 ft 6 inches to w/c there is a pocket door at toilet room the lav would vent the toilet. very simply. the tub separately vented likely in side wall perhaps remove the 3 inch 90 and replace with a 3 inch low heel outlet to pick up tub with a street 1/4 bend on top . but looks like a pretty basic job like John says.

Yeah, I was planning on running the vent ~3' from the toilet to allow space behind the lav for a niche in the wall.

I've been researching my shower options some more and not entirely sure where the drain might end up, so not sure if the 2" side inlet or low heel inlet would be the best.

If I have to run through the floor joists there is a supporting wall down below and with some additional reinforcement I believe it should be fine.

Any preference on the side inlet or low heel inlet all things being equal?

 

[Jeff H Young]

I was thinking it was a tub but looking at it now looks like a shower framed . I know the drawing might not be final plan but i find that type shower kind of claustrophobic , so based on that and not knowing where drain is going or if there is wall there or a glass enclosure not sure where vent or p trap would be so not sure how to rough in the shower

 

[PBFR20]

I was thinking it was a tub but looking at it now looks like a shower framed . I know the drawing might not be final plan but i find that type shower kind of claustrophobic , so based on that and not knowing where drain is going or if there is wall there or a glass enclosure not sure where vent or p trap would be so not sure how to rough in the shower

I'm glad I posted this here.

If you think that is claustrophobic you should try the existing one.
You make a good point, may have to create a mock-up to get a better feel for it or ask the boss.

 

[wwhitney]

Wayne might jump in with a better idea

Not sure if my ideas are any better, but since you invoked my name and I happened to notice I'll give my thoughts. : - ) I think if you use @wwhitney I might actually get a notification to that effect.

With 2x8 floor joists, fitting a 2" shower trap in the joist bay can be tricky, as the center line of the outlet of a solvent weld 2" trap is 5-15/16" above the bottom of the u-bend. [That puts the top of the outlet pipe at 7-1/8" above the bottom of the u-bend, and the hub adds approximately another 1/4", or possibly taller than the joist.bay]. Or with a special "low profile" 2" trap it's 5-3/4". [Now it at least fits in a 2x8 joist bay, which is probably the reason this fitting exists.] This is per the Charlotte catalog, I have not seen the low profile version in person.

Also, a 2x8 floor joist with a 2-1/2" hole in it requires a repair/reinforcement for the hole, unless it's an old 2x8 that's at least 7-1/2" tall. Even then the maximum height at center for a prescriptive 2-1/2" hole on a 7-1/2" tall joist is 4-1/4" above the bottom of the joist. Which is only marginally compatible with the minimum trap outlet height.

One way to deal with this is to use a 1-1/2" trap on the shower, which the IPC allows if the shower head flow is 5.7 gpm or less. Then your trap outlet height is 4.8" above the bottom of the u-bend, and a 2" hole can be put in any 2x8. But a 2" trap is generally preferred.

Another way to deal with this is to put the shower drain at the bottom of the page in the same joist bay as the 3" WC drain and the 3" stack below. Then no joists need drilling. You could do a mono-slope shower with a trench drain at the bottom of the page. You'd still need to check the height of the drain assembly, as the inlet of a 2" regular solvent weld trap is 3-7/16" above the bottom of the u-bend (low-profile is 1/8" higher), not counting the hub. Plus you don't want the trap weir (level of water in the trap when not draining) to be above the bottom of the trench; the trap weir on a 2" regular solvent weld trap is 4-3/4" above the bottom of the u-bend (low profile is 3/16" lower).

Regardless, once you have the lav drain, the WC drain, and the shower drain all in the same joist bay, you can wet vent everything from the lav drain if you desire. Under the IPC, the WC drain doesn't have to be last on a horizontal wet vent, and there's no limit to the length of its trap arm. So you can join the lav to the WC to wet vent it, and the combined drain can join the shower horizontally to wet vent it. The resulting shower trap arm is limited to one pipe diameter of fall, which also means 6' of length for a 1-1/2" trap or 8' of length for a 2" trap if you perfectly achieve the minimum allowable slope of 1/4" per foot. If you have a section of sold wall between the vanity and the shower you could also dry vent the shower trap arm as it passes under that wall, should that end up easier for some reason.

One complexity here is the configuration in the joist bay just above the 3" stack. If all 3 fixtures were on the same side of the stack, their drains could combine horizontally and just go to a quarter bend at the top of the stack. But you have the shower on the opposite side of the stack, and it needs to combine horizontally with the lav/WC, and then everything has to go to the stack. This post is already long, so we can come back to that issue if everything else gets settled and that is the sticking point.

Cheers, Wayne

 

[PBFR20]

Not sure if my ideas are any better, but since you invoked my name and I happened to notice I'll give my thoughts. : - ) I think if you use @wwhitney I might actually get a notification to that effect.

With 2x8 floor joists, fitting a 2" shower trap in the joist bay can be tricky, as the center line of the outlet of a solvent weld 2" trap is 5-15/16" above the bottom of the u-bend. [That puts the top of the outlet pipe at 7-1/8" above the bottom of the u-bend, and the hub adds approximately another 1/4", or possibly taller than the joist.bay]. Or with a special "low profile" 2" trap it's 5-3/4". [Now it at least fits in a 2x8 joist bay, which is probably the reason this fitting exists.] This is per the Charlotte catalog, I have not seen the low profile version in person.

Also, a 2x8 floor joist with a 2-1/2" hole in it requires a repair/reinforcement for the hole, unless it's an old 2x8 that's at least 7-1/2" tall. Even then the maximum height at center for a prescriptive 2-1/2" hole on a 7-1/2" tall joist is 4-1/4" above the bottom of the joist. Which is only marginally compatible with the minimum trap outlet height.

One way to deal with this is to use a 1-1/2" trap on the shower, which the IPC allows if the shower head flow is 5.7 gpm or less. Then your trap outlet height is 4.8" above the bottom of the u-bend, and a 2" hole can be put in any 2x8. But a 2" trap is generally preferred.

Another way to deal with this is to put the shower drain at the bottom of the page in the same joist bay as the 3" WC drain and the 3" stack below. Then no joists need drilling. You could do a mono-slope shower with a trench drain at the bottom of the page. You'd still need to check the height of the drain assembly, as the inlet of a 2" regular solvent weld trap is 3-7/16" above the bottom of the u-bend (low-profile is 1/8" higher), not counting the hub. Plus you don't want the trap weir (level of water in the trap when not draining) to be above the bottom of the trench; the trap weir on a 2" regular solvent weld trap is 4-3/4" above the bottom of the u-bend (low profile is 3/16" lower).

Regardless, once you have the lav drain, the WC drain, and the shower drain all in the same joist bay, you can wet vent everything from the lav drain if you desire. Under the IPC, the WC drain doesn't have to be last on a horizontal wet vent, and there's no limit to the length of its trap arm. So you can join the lav to the WC to wet vent it, and the combined drain can join the shower horizontally to wet vent it. The resulting shower trap arm is limited to one pipe diameter of fall, which also means 6' of length for a 1-1/2" trap or 8' of length for a 2" trap if you perfectly achieve the minimum allowable slope of 1/4" per foot. If you have a section of sold wall between the vanity and the shower you could also dry vent the shower trap arm as it passes under that wall, should that end up easier for some reason.

One complexity here is the configuration in the joist bay just above the 3" stack. If all 3 fixtures were on the same side of the stack, their drains could combine horizontally and just go to a quarter bend at the top of the stack. But you have the shower on the opposite side of the stack, and it needs to combine horizontally with the lav/WC, and then everything has to go to the stack. This post is already long, so we can come back to that issue if everything else gets settled and that is the sticking point.

Cheers, Wayne

Thanks guys for all the input.
I'll check back once I confirm the drain location for the shower, and any other obstacles/questions that may arise.