Basement bathroom venting puzzle

[BenjaminCoop]

Hi all,

I'm putting a bathroom in my basement and am currently working on the plans to submit to the city. With my layout, I am planning to use an AAV behind (in the wet wall of) the shower, in a 12" wide space that will likely double as a narrow storage cabinet. This will vent the shower and, ideally, serve as a wet vent for the toilet, as per the following diagram:

My question regards the turn from the shower drain past the AAV vent takeoff. Per the Ohio Revised Code:

708.1.4 Changes of direction. Where a horizontal drainage pipe, a building drain or a building sewer has a change of horizontal direction greater than 45 degrees ( 0.79 rad), a cleanout shall be installed at the change of direction. Where more than one change of horizontal direction greater than 45 degrees ( 0.79 rad) occurs within 40 feet (12 192 mm) of developed length of piping, the cleanout installed for the first change of direction shall serve as the cleanout for all changes in direction within that 40 feet (12 192 mm) of developed length of piping.

Does my shower drain meet the criteria of a cleanout in this situation? It seems to me that without a cleanout meeting the above requirements, I will need to reimagine my DWV layout.

Thanks for any input!

Benjamin

 

[wwhitney]

Image not showing. Wayne

 

[Sponsor]

 

[BenjaminCoop]

Sorry about that! Let's try again:

 

[Reach4]

The change of direction is usually going to be primarily in the trap.

Your drawing is too Picasso, and not enough da Vinci. Is the trap swivel doing the bending? If so, you are not too sharp. If it is elbows, you might be too sharp.

Vertical trap takeoff can be santee or combo, with the bend sloping with the flow.

 

[BenjaminCoop]

Thanks for your reply, although "Picasso" is too kind for my scribbles! I think I had a major brain fart and forgot I could run the trap arm north ("up" in my picture) to the point where I could use the trap swivel to do the 90 degree (or so) bend and then pick up the vent. Does this look better?

 

[Reach4]

I think so. Is the santee placement for the AAV due to where a wall is? I am not a pro.

 

[BenjaminCoop]

I think so. Is the santee placement for the AAV due to where a wall is? I am not a pro.

Yes, there will be a wall bump-out there (coming down from the top of the picture) specifically to create a small space to house the AAV and maybe some extra toilet paper. Thanks for you input!

 

[wwhitney]

Generally the shower trap should be directly below the shower drain. While the horizontal offset you have drawn is allowed, I believe, it is unusual and would probably be a place for shower scum to accumulate. And unlike the plumbing under a sink, you won't be able to access and disassemble it for cleaning.

A floor plan showing the shower, the walls, the shower drain, the closet flange, and any existing drain you need to meet up with would be helpful for making suggestions. Is there not a nearby lavatory that could be conveniently plumbed with its drain running into the shower fixture drain to wet vent both the shower and WC?

Cheers, Wayne

 

[BenjaminCoop]

Thanks Wayne. I'm not super interested in providing our basement with more dank odors so I see why avoiding the horizontal offset between the fixture drain and trap is ideal. Here is my layout:

As you can see, the lav is on the wrong side to provide a convenient wet vent. My existing sewer line is not very deep and the floor slopes slightly toward the floor drain, so having the flow go left is not really an option. I am planning to vent the lav and laundry separately (either individually or with a common vent - still working on that) and tie those drains into the new proposed 3" branch.

 

[wwhitney]

So the cross hatched walls are concrete and you can't run any plumbing in them? Because if you could, then you have the option to run the lavatory drain horizontally through the wall(s) and enter the slab between the shower and WC. Which would make wet venting simple. [The space is big enough that you could consider framing out the wall behind the WC to contain the lav drain to allow this.]

On option you could consider is sending the 2" shower trap arm straight to the right; it just needs to be vented within 8' if you maintain a perfect 1/4" /foot slope. The IPC allows the WC to be upstream of the shower on the wet vent. So the WC drain would also start off to the right from the closet flange, then turn 45 degrees to join the shower trap arm with a wye just before the 8' mark. Then the lav could enter the slab and only briefly have to go to the left to hit the WC drain, wet venting it and the shower trap arm. [The geometry might work for you to conceal the lav drain in the vanity or its toespace and enter the slab at the upper left corner of the vanity, heading down and to the left to hit the WC drain with a flat combo.]

If you want to use an AAV in the area indicated, you could send the shower trap arm up on the page (and possible a little to the left of center, just what you can get with the u-bend), then hit a LT90 to turn to the right, under the marked area, and then an upright combo for the AAV takeoff. (IPC allows a san-tee on its back, but if you have room a combo is better).

Hopefully the window in the shower is a fixed window with a non-wood frame that you will integrate into the shower wall waterproofing system behind the tile.

With the washing machine, bear in mind the IPC requirement (406.2?) that if you use a standpipe, when the standpipe drain joins another drain, the combined drain needs to be at least 3". If you drain the laundry machine through the laundry sink, this doesn't apply.

Cheers, Wayne

 

[BenjaminCoop]

So the cross hatched walls are concrete and you can't run any plumbing in them? Because if you could, then you have the option to run the lavatory drain horizontally through the wall(s) and enter the slab between the shower and WC. Which would make wet venting simple. [The space is big enough that you could consider framing out the wall behind the WC to contain the lav drain to allow this.]

The cross-hatched walls shown are my 2x4 stud walls, and behind them is concrete to the north (up) and west (left). I need to put R-13 in those stud walls so I can't run plumbing through them, but I would consider furring out that north wall behind the WC or making it 2x6 to allow for one of your suggestions.

On option you could consider is sending the 2" shower trap arm straight to the right; it just needs to be vented within 8' if you maintain a perfect 1/4" /foot slope. The IPC allows the WC to be upstream of the shower on the wet vent. So the WC drain would also start off to the right from the closet flange, then turn 45 degrees to join the shower trap arm with a wye just before the 8' mark. Then the lav could enter the slab and only briefly have to go to the left to hit the WC drain, wet venting it and the shower trap arm. [The geometry might work for you to conceal the lav drain in the vanity or its toespace and enter the slab at the upper left corner of the vanity, heading down and to the left to hit the WC drain with a flat combo.]

I will have to look into this and do some sketches to figure out what all it entails.

If you want to use an AAV in the area indicated, you could send the shower trap arm up on the page (and possible a little to the left of center, just what you can get with the u-bend), then hit a LT90 to turn to the right, under the marked area, and then an upright combo for the AAV takeoff. (IPC allows a san-tee on its back, but if you have room a combo is better).

Wouldn't this require a cleanout at the LT90 per the code reference in the OP?

Hopefully the window in the shower is a fixed window with a non-wood frame that you will integrate into the shower wall waterproofing system behind the tile.

Yes, and that is one reason for the chosen layout: to incorporate a window into the shower.

With the washing machine, bear in mind the IPC requirement (406.2?) that if you use a standpipe, when the standpipe drain joins another drain, the combined drain needs to be at least 3". If you drain the laundry machine through the laundry sink, this doesn't apply.

Thanks - I had recently discovered this little tidbit. Apparently some AHJs in Ohio let a 2" drain pass for both washing machine and laundry sink, but better safe than sorry. That's the part of the layout where I have the most room and flexibility anyway.

I appreciate you taking the time to weigh in, and will see what I can do with your suggestions!

Benjamin

 

[wwhitney]

I need to put R-13 in those stud walls so I can't run plumbing through them

That doesn't follow, it's done all the time. If you're using batts you just split the batt to go around the pipe and compress it a bit on each side. So obviously it's not R-13 at that one point, but overall it hardly affects the thermal performance of the wall.

A couple comments: R-13 in a 2x4 wall is a dead minimum, a higher density fiberglass batt would get you R-15, if I recall. And when insulating a wood frame wall in front of a concrete basement wall with earth on the outside, the details of the vapor barrier(s) and where they go are very important. You don't want moist air from the shower penetrating through the drywall and batts to condense on the concrete; nor do you want any ground moisture coming through the concrete.

So if you haven't considered this issue, read some of the threads on it here, and Dana know a lot so believe anything he posts.

Cheers, Wayne

 

[wwhitney]

P.S. The IPC has a detail for a laundry sink next to a washer standpipe to share the same trap, which would negate the need to upsize the drain to 3" at that point.