Planning Basement Bathroom in MN

[newBasementMN]

We're almost ready to start breaking up the floor, but have some questions. This forum has been invaluable as a reader, and I was able to answer so many questions just by reading what everyone else had to say! I've done plenty of supply lines as an amateur, but never DWV. We're in urban Minnesota, and everything will be permitted/inspected. Basement on slab, built 1950s

(1) we want to remove the current floor drain. Do we have to remove all the pieces, or can we just cap and bury any parts that aren't in our way?
(1b) would it ever be allowed to leave the connection between the old floor drain and the main drain line? This won't be protected by the backwater valve, but would be capped.

(2) we need to add a backwater valve. Do we want a cleanout upstream, downstream, or both? What's code vs. what makes best sense?
(2b) where do we need cleanouts on this whole thing? Under the vanity, right? And then just about everything accumulates 135 degrees before joining the main line, so where else? Does the floor drain count as a cleanout?

(3) Does the floor drain need its own vent? (edit: inspector says yes). Since drain is in the middle of the room, can the vent follow our trench back "upstream?" Like we run two pipes side by side, one waste, one vent, in the trench and it exits closer to the laundry standpipe? I don't really understand wet venting, but does that apply here at all?

(4) Can the laundry standpipe also receive water softener discharge? Is the answer here just to do two standpipes, side by side, vented separately? (edit: inspector says air gap then into floor drain for this, but that sounds like it'll just splash everything. Would it be better to share one standpipe or build two?)

(5) When everything drains into the main line, does it need to be at the same elevation? Or can it come from above and "dump" into a WYE that's rotated at least 45 degrees toward vertical? This questions depends on how deep the drain line is, but if we have the opportunity to save some digging by adding a vertical drop, I'm all for it! (yes everything will be sloped properly, this is more "can we go horizontal to vertical to horizontal like that?")

(6) With this drawing, the toilet needs its own vent, right? Should we switch to a right-hand bathtub so that the toilet can share its vent?

(7) What other changes would you suggest for this plan?

Sorry if that's a lot all at once. I really appreciate all your help.

 

[Reach4]

MN adopts with amendments
UPC 2018

 

[Sponsor]

 

[wwhitney]

1) In all cases it makes sense to remove as much of the branch drain serving the existing floor drain as possible.

If you further disconnect the branch drain from the building drain, you could abandon individual segment(s) of pipe under the slab, but it would be prudent to cap the ends of those segment(s), rather than leave a void space under the slab where soil could migrate into, resulting in a void under the slab.

You don't have to disconnect that branch drain from the building drain, but if you don't, you must properly cap the free end. And as you are installing a back-water valve, you'd want some confidence that the drain you leave and the cap you use is watertight.

2) I have no particular knowledge about this; see https://up.codes/viewer/minnesota/upc-2018/chapter/7/sanitary-drainage#710.0
on the backwater valve, and https://up.codes/viewer/minnesota/upc-2018/chapter/7/sanitary-drainage#707.0 on the cleanouts.

3) Dry vents may not be horizontal under the floor, although there is a limited exception that could apply here. But the simplest way to vent the floor drain would be to design the branch drain from the WC's vent takeoff to the floor drain as a circuit vent; see https://up.codes/viewer/minnesota/upc-2018/chapter/9/vents#911.0

The WC will need a vent connection within 6' run measured along the pipe from the closet flange. That could be a dry vent taken off under the wall between the tub and the WC. That dry vent would then let the tub and the floor drain be circuit vented. The lav and standpipes would need their own dry vents, as their traps are above the floor.

4) I believe you could use one standpipe to receive both discharges, and there are devices to facilitate this. Or you could use two standpipes that share one dry vent takeoff. No opinion on the merits of the two different approaches.

5) No need for your new branch drain to meet up with the building drain at the building drain's elevation. But if you use circuit venting, the portion of the drain that is a circuit vent has to all be sloped at between 1/4" per foot and 1" per foot, i.e. no jogs downwards. After the floor drain you could jog downward, e.g. by a 45 to an upright wye added to the building drain.

6) If you use circuit venting, that can vent the bathtub.

Cheers, Wayne

 

[Reach4]

Repiping to bring the upstairs drainage to the downstream side of the backwater valve is the better ay. Do you ever get sewer backups? If yes, consider "overhead sewers". There may be a government program to contribute to that.

 

[wwhitney]

Repiping to bring the upstairs drainage to the downstream side of the backwater valve is the better ay.

No sure what you mean, the proposed plan does have the upstairs drainage connected downstream of the backwater valve. The stack from upstairs is mislabeled SP for main standpipe.

Cheers, Wayne

 

[Reach4]

No sure what you mean, the proposed plan does have the upstairs drainage connected downstream of the backwater valve. The stack from upstairs is mislabeled SP for main standpipe.

Cheers, Wayne

I had not followed that aspect of the diagram, but good. Backwater valve that is "normally open" is much better than a flapper valve. Flapper valves are pretty much guaranteed to leak with time.

With "overhead sewer" there is a vented septic pit with pump (grinder pump if toilet) added to handle the basement waste. Also, they make a new sewer exit thru the side wall and feed the city sewer thru that. I don't know if that is always implied by "overhead sewer", but in the programs I have read about, it was a requirement. That may have been in case an under-floor pipe had a leak.

 

[newBasementMN]

I apologize about my abuse of terminology. Still definitely learning! Yes, what I labeled as "main standpipe" is the stack that drains all upstairs fixtures and eventually sticks out of our roof. The backwater would only protect the new basement plumbing. We have zero concerns about backups, but we need to add it per code.

I apologize for my talk about a horizontal, under-slab vent. That was silly of me and I know better. Trying to stuff this much technical information into my head all at once gives me even more appreciation for professional plumbers than I had before!

I'm including a new top-down plan for our bathroom that includes a vent for the floor drain (and the rest of the vents marked as well). There should be just enough clearance to run the vents above the bathroom door, and if that doesn't work, I'll leave them exposed in the utility room instead to maintain slope.

How terrible is this plan for the floor drain? Taking 180 degrees in quick succession like this doesn't seem like a good idea, but we can use the cleanout under the vanity if needed. The alternative, as far as I can tell, is to have a vertical vent pipe sticking up out of the slab somewhere, and I'm just not finding a good place for it. (Best option we've come up with is moving floor drain to the other side of the existing drain line, about halfway between water softener and water heater, and adding a second backwater valve to protect it). If we go that way, any idea whether an in-fixture backwater like this one https://www.menards.com/main/p-1444421393226.htm would meet code or might be accepted by AHJ?

I tried to read about Circuit Venting, but almost everything I found pertained to commercial installations with rows of water closets. It's important to me to be able to understand how my installation meets code. I'm not sure I could explain it to an inspector if they have doubts. At least one specific technical question we've asked the city so far has been met with "that might be okay, we'll see during inspection" type responses, which do not really inspire confidence. I just really want to get this right the first time!

One more question: What specific connection pieces do we need to make the "vertical" drop into the existing line? I've attached a diagram of what I'm picturing. Can we do it like this where the two drain lines cross perpendicular? Or is it better to go back to my previous plan where I had them running parallel before the drop? And how is a drop best executed? Pair of 45s into the WYE, or a long sweep 90? Something else? Thanks again.

 

[wwhitney]

On the "Final Junction" if the upper drain is exactly perpendicular in plan from the lower drain, you can use a quarter bend rolled 45 degrees from having its outlet pointing straight down to dump the upper drain directly into the branch inlet of a wye on the lower drain with its branch inlet rolled upwards most.

As to the layout, how about something like the attached (ignore your green lines that I left in and just drew on top of)? Blue circle = 2" vent takeoff, green circle = 1.5" vent takeoff, blue = 2" drain under the slab, red = 3" drain under the slab. You have dry vent takeoffs for each fixture, with the exception of the floor drain, which is wet vented by the lav.

Cheers, Wayne

 

[newBasementMN]

I want to thank you for your help. It has been really valuable. I actually saw your response within an hour of posting, but unfortunately my computer had some issues and sick kids etc etc. Since then I have broken open the slab and have started routing some lines and dry fitting everything. The existing drain line isn't as deep as I had hoped, so we will meet it at the same elevation instead of "dumping" down into it. Two questions have come up.

First, can the bathtub be wet vented by the laundry standpipe? Does the answer change if I use 2" for that vent instead? And If I add a second standpipe right next to it for the water softener discharge, could all three share a single 2" vent attached right after the first standpipe? Now that I'm handling real fittings in the real space, I'm not sure I have room to do a dedicated vent for the tub without moving the laundry (which would be a terrible idea with the floor open!).

I'm attaching a very crude sketch. The standpipe tees have to happen inside the wall, so their waste lines will happen under the wall. I don't think I have space for both the WYE that joins the bathtub drain to this waste line and another fitting on the trap arm that will vent the bathtub. There isn't much space at all to run the waste line closer to the existing laundry (outside the footprint of the stud wall). Would it be acceptable to connect a vent at point A or B marked on the drawing? They both look silly to me, but i guess which is "less silly" if wet venting the tub past the standpipe doesn't work?

Second, why is my Fernco coupler leaking? I have 4" iron pipe. I glued stubs of 4" PVC into the fitting that will drain the new bathroom. Then I removed a length of iron pipe and screwed on the couplers. I got the shielded kind with four band clamps, marked for CI-Plastic (had other acceptable pairings, like CI-CI, but that's the one that matters to me!). It's a tight fit on the PVC and also difficult to slide onto the iron. I tightened down the clamps, and turned on all the water upstairs. There was a small stream coming out of both Ferncos.

I removed the Fernco and used an old sanding belt to remove the lumpy/dirty parts of the iron pipe, cleaned everything, and put it together again. Still dripping, but not as much. Since then I've really let the clamps have it, and they're probably beyond the 60 in-lb recommended, but tightening them seemed to reduce the dripping. At this point when I dry off the pipe then run water upstairs, a paper towel on the pipe will still pick up a drop or two of moisture.

Ideally we don't want any moisture leaving that pipe, right? So what are my options? My cuts on the iron aren't perfect because a sawzall can wander, but is that enough to cause an issue? The Fernco is 4" wide and definitely covers all of the small "gaps" by more than an inch. When lowering the PVC into place, if it was anything other than perfectly straight it wouldn't fit. I could try to cut them again more cleanly (and glue up a new fitting), but what kind of tolerance is there in these connections? Should I consider any additional chemical or mechanical fasteners? Silicone? Epoxy?

Thanks again for everything. Even when I'm not posting my own questions, I've been searching other people's to find great answers to other issues that have come up.

 

[Jeff H Young]

tub needs its own vent must not be Horrizontal wet vented by non bathroom fixtures

 

[wwhitney]

First, can the bathtub be wet vented by the laundry standpipe? Does the answer change if I use 2" for that vent instead? And If I add a second standpipe right next to it for the water softener discharge, could all three share a single 2" vent attached right after the first standpipe?

No, and no. The bathtub could only be wet vented via a drain that carries only bathroom fixtures (that excludes the laundry and the softener discharge) and which carries a dry-vented bathroom fixture (typically the lavatory).

Now that I'm handling real fittings in the real space, I'm not sure I have room to do a dedicated vent for the tub without moving the laundry (which would be a terrible idea with the floor open!).

I'm finding that hard to believe. To dry vent the tub, you just need to put a combo under the wall that has a 1.5" branch inlet pointing up for the vent, and a 2" horizontal outlet for the tub drain. The inlet can be 1.5" or 2" depending on whether you use a 1.5" or 2" trap for the tub, and the inlet receives just the tub trap arm (no other drainage). The upside of the 2" tub trap is that the trap can be up to 5' from that vent; with a 1.5" tub trap, the trap needs to be within 42" of the vent.

If you're having trouble fitting everything in that wall, make a scale elevation drawing of the wall.

It should be possible for the laundry and water softener to share a single standpipe, I would think; it's just a matter for having a way to secure both discharges to the standpipe inlet, and I seem to recall there are products made to do that. Although perhaps those are just for a slow discharge like a gravity A/C condensate drain, not a faster pumped discharge.

Second, why is my Fernco coupler leaking?

No opinion on this one, maybe someone with more hands on experience can help.

Cheers, Wayne

 

[Jeff H Young]

sounds like a few possible causes of leaks the cast iron pipe or fittings can have a seam or parting line on it that needs to be ground off and made round letters stamped on fittings as well. I used a sticky kind o9f mastic called black swan years ago because as Journeyman we were ordered to on certain places that had leaked or expected to not hold test some co workers thought it was good stuff I not a fan of that type stuff or silicone but something tacky like permatex high tack gasket sealer might work
having around inch shy of bottomed out is kinda short also be sure youve got correct band 3000-44 be good for 4 inch castiron to 4inch plastic

 

[newBasementMN]

It looks like I bought shielded 1056-44 instead of the 3000-44. Mine is listed with I.D. 4.58" and the 3000 says 4.36"/4.44" so maybe the extra one or two tenths would make the difference. I had a lot of trouble sliding it off of the PVC onto the iron, but I suppose I only ever have to do it one more time if I get it right! I will also check and see if there's anything else keeping it out of round. Staring at all the Fernco options at the store, I guess I figured the one that was twice as long (and three times as expensive) would work better, but it sounds like that might not be accurate here.

For the bathtub vent, I appreciate the strong "No!" answers. I wasn't finding anything definitive in my searches but it's good to know I was on the wrong track. I think I'm explaining the situation poorly, so I drew a (hopefully better) picture.

If I had removed the laundry before breaking up the floor, this wouldn't be an issue. I could have routed the drain line parallel to the stud wall where the dryer is. Among other discoveries, our slab has what might be a very large patch but it's only about 1" thick cement versus the 3-4" thick concrete everywhere else. The seam between them is irregular but also right under the laundry so I don't want to go any closer than I have to. Because I'm foolishly optimistic sometimes, we're talking about clearances of only a couple inches between the stud wall (which will remain unfinished on the outside face) and the laundry, which is moved as far as it can go in that direction.

So yes, ideally there would have been plenty of room to make everything work. Instead I will need to run the drain for the standpipe directly under the 2x4 plate of the stud wall. I just can't see a way to make all the connections I need in there. I've seen side inlet WYEs, but I don't think one exists that is 2 inches everywhere and I'm not sure it would be code if it did exist.

I can take actual pictures if needed, but at this point that part of the room is still just sand.

 

[wwhitney]

If I had removed the laundry before breaking up the floor, this wouldn't be an issue.

So why not remove it now and break up under the laundry? If some of your existing slab is only 1" thick, that deserves to be replaced during this project.

If in your last diagram the pink rectangle is really a no excavation zone, then my first question would be do you have extra depth? If you do, you could run the standpipes drain under the tub drain, and after the tub gets its vent takeoff, it can turn down with a 45 into an upright wye.

Or another possibility is to run the two drains side by side for a short segment, and then join them with a horizontal arrangement of a street 45 into a wye. That arrangement works if the parallel drains are 4-1/4" apart center to center, which means their joint footprint is 6-5/8" wide. Putting the edge of the standpipe drain at the edge of the 2x4 puts the edge of the tub drain 3-1/8" outside of the 2x4 footprint. But your vent take off on the tub drain could be a combo (or wye) rolled 45 degree off vertical, going to a 45 (or 60) to turn up to vertical. As long as your drains are deep enough, that should allow your vent to emerge out of the slab under the wall, rather than in front of the wall.

In some sense these two options are really the same, in that if you use an arrangement of a street 45 going into a wye to join two parallel drains at the correct center-to-center distance, that center-to-center offset doesn't have to be purely vertical or purely horizontal, it can be at any angle.

Cheers, Wayne

 

[Jeff H Young]

figured the wrong band was possible or likely you are doing good on this job.
Late to this party but if there is space to put combi with vent close to wall but clear of bathtub why fight it ? rise up through slab thgrow a couple 45s to get vent in wall . and btw the 2 stand pipes I see as un nesesary Id put a wye in the stand pipe and second small box for the softner drain or brainstorm something else I didnt look where this softener was of cource your 2 stand pipes works fine if you prefer