What's a good minimum working distance between closet flange and floor joist?

[MG70]

I continue to work on a back to back bath remodel where there was originally a single bath. My initial plan was for a couple of 5'X8' bathrooms, each with a 3'X5' shower at the end, but the floor joists running front to back (perpendicular to the width of the bathrooms and the purchased shower bases) are causing me to have to widen the bathrooms in order to install the toilet/closet flanges at 12 1/2" from the finished walls. As is, it looks like the Left side bath ends at 64" and the Right side bath starts at 70 1/2".

I'm wondering if the pros have any suggestions on how far from a joist I should install my closet flanges? In other words a good, minimum, working distance from the bottom extension of the closet flange to the side of the floor joist? I'll be welding/gluing a 3" PVC pipe inside, not around or outside the closet flange.

Another consideration is I don't want too big a gap behind the toilet tanks. Right now I'm planning for 12 1/2" to the finished wall but if you have a better or more realistic number, please post below. I'd rather be safe than have to fix the subfloor and underlayment! Sticking to the standard 12" toilets as opposed to 10."

Lastly, due to the separation/plumbing wall falling on the 64" floor joist, I'm planning on building a 2X6 stud stall to give me a little more space for fitting pipes and because there's already some wires and stuff underneath. I figure the corresponding space can be used for more width in the shower niche I'll be building later.

Thanks for any and all help and I hope everyone is having a safe weekend!

 

[Reach4]

I suggest you make a sketch and post that.

 

[Sponsor]

 

[MG70]

Reach4, thanks for the quick reply! My sketching abilities and lack of drawing programs on my laptop make me believe actual pictures will be easier to understand.

With that in mind, I'll simply my questions.

Is there a minimum distance that I should install the closet flange seen on the left hand side next to the floor joist, where the orange Home Depot pencil is located?

Is there a minimum distance for a 2" pipe to run next to an adjacent floor joist where the PVC coupler is pictured?

Both these distances and the fact that the proposed wall partially sits on top of a joist (which I think is a good thing since it will be holding some weight in the form of Hardie Backer and tile in the shower stall) are forcing me to make the bathrooms wider than I had planned. I'm sure I'm overthinking this and it's no big deal. I imagine I can install the PVC as close as I can get to the joist, perhaps leaving and expansion gap of 1/4" or something similar. The only real implication to me at this point is making the kitchen area further smaller.

For anyone curious, on the upper left hand corner of the pic there's a black PVC 2" drain and a yellow yard stick marking the location of the 36X60 shower base.

The horizontal tape measure marks the minimum required 30" distance where the toilet would have 15"space on each side.

The vertical tape measure marks where the separation-plumbing wall would be.

Yes, there's still rotten wood to be removed before replacement. Those with a keen eye will notice that the walls were framed over the plywood subfloor and MDF underlayment in the bathroom. On other parts of the house, they were framed over the hardwood floor. Peculiarity of 1970's prefab construction, I imagine. Surprised me, that's for sure.

I hope everyone has a safe weekend!

 

[Reach4]

Reach4, thanks for the quick reply! My sketching abilities and lack of drawing programs on my laptop make me believe actual pictures will be easier to understand.

With that in mind, I'll simply my questions.

Is there a minimum distance that I should install the closet flange seen on the left hand side next to the floor joist, where the orange Home Depot pencil is located?

1. If your computer is Windows, you have Paint.
2. If you cannot run Paint, consider masking tape and a crayon/marker.
3. Many words, and I still don't know where the walls are and which ways the people on the toilets sit.
4. Where you placed the closet flanges does not seem to interfere with the joists. There are reasonable offset closet flanges, but I don't see a need for that.
5. Consider closet bends for the toilet. They will accept an outside 4-inch flange or a combo closet flange glued to the inside. Go for a stainless steel ring, such as https://www.homedepot.com/p/Oatey-F...Cap-and-Stainless-Steel-Ring-435922/305248440

 

[MG70]

It was easier and faster to draw by hand than with Paint which I did find on my computer but have never used. Hopefully the labeling will make it easier to understand. The main focus is if there's anything I should be careful with in the positioning of the "Diving/Plumbing wall" and the closet/toilet flange and 2" PVC pipe coupler (that represents drain and venting) in reference to the joists. I can move things to the right of the drawing but not the left.

I assume the ring for the closet/toilet flange should be fastened to the subfloor and underlayment and not touch the floor joist.

I also assume that the floating vinyl floor I'm planning to install (but have not purchased) is too soft for the weight of the toilet and that perhaps I'll need to buy a rigid extension ring equivalent to the height of the vinyl floor for the toilet flange or simply install a thicker wax ring (I've gone with the flexible silicone or plastic the last couple of times and found it much more forgiving when having to pick up and readjust the toilet...not as big a mess).

In my amateur DIYer eyes, I couldn't find a better solution for this very basic layout, so if anyone sees a better way to put this together, please let me know.

Thanks again and a safe week for all!

 

[Reach4]

I had presumed that the two closet flanges in the first photo were where you proposed to have the them located. Your sketch says not.

You were concerned with the location of the joists with respect to the closet flanges before. Still concerned? I marked up your sketch to show the joists. If you are concerned with that toilet on the left clearing the joist, you could use an offset closet flange such as https://www.supplyhouse.com/Sioux-C...-1-1-2-Offset-Closet-Flange-with-TKO-Knockout That gives a 1.5 inch offset, but will still pass a 3-inch ball.

You could glue that into a https://www.supplyhouse.com/Spears-P330-342-3-x-4-PVC-DWV-90-Street-Closet-Elbow
The 4-inch part goes up, so the photo in that listing is upside down.

Also worth considering are outside compression closet flanges. With glue, you need to get it right the first time. With compression, you get a chance at do-overs. The cast iron 4-inch outside compression Code Blue flanges even have an offset version, which offsets 1 inch.

Also, a 12 inch rough (to the finished wall) would be better than 12.5. A 12 inch rough toilet will actually fit an 11 to 11.5 rough.... so they leave the margin, and you don't want to add your own additional margin.

 

[MG70]

I'm sorry, I didn't have a way to prop up the toilet flange on the right in the pic because I'd torn down the insulation. I'm happy with the layout on top as I didn't lose a whole lot of space. I had measured the joist spacing from the basement before buying the shower bases on sale many months ago, but it was only after I tore the rotten subfloor out that I noticed I'd have to move some things around due to clearance.

I'm looking forward to the actual plumbing, which I usually like. I foresee the shower drains as being the trickiest as they're the farthest from the main drain branch and the closest to the basement exterior wall. I may need to get creative tying them in with the others.

I'm not convinced on the added benefit of a small section of 4" drain pipe when the waste comes out of what looks to be 2 3/4" after having travelled through an even smaller ceramic p trap. But I'll research it some more and exchange parts if I see a benefit.

Thanks for the info. on the 12" rough being better as it'll give me more working room and leave a smaller gap behind the tank. I like to weld/glue parts, including P-traps. I weld/glue whatever I can if it's in my property. I can't stand leaks, especially hidden in cabinets. I don't like water lines to fridges and I'm not even thinking of installing a garbage disposal in this house because they always leak and from the look of things it'll be just me living here and I never use them anyway. It's also my first time living with a septic system so there's an even greater incentive for not throwing solids (or oils and grease) into the kitchen sink drain.

Btw, thanks for the info on supplyhouse. I was made aware of them in another thread where I needed a double fixture fitting for the lavs in this project. I could not find the part locally and they had it for a decent price and shipped it extremely fast.

Thanks again and I hope you have a good evening.

 

[Reach4]

I'm not convinced on the added benefit of a small section of 4" drain pipe when the waste comes out of what looks to be 2 3/4" after having traveled through an even smaller ceramic p trap. But I'll research it some more and exchange parts if I see a benefit.

A 4X3 closet bend would let you use an inside 4 inch glued flange, or an outside compression 4 inch flange or an inside compression closet flange. But a 3-inch medium bend is OK also.

If you use a glued closet flange, those with a stainless steel flange are better than the all-plastic.

 

[MG70]

For your remodel, install the closet flanges at least 2–3 inches from the side of the floor joists. A rough-in distance of 12–12 1/2 inches from the finished wall works well for standard 12" toilets, giving minimal gap behind the tank. Widening the bathrooms slightly to accommodate the flanges and using a 2x6 stud stall for plumbing clearance is a practical solution.

I appreciate your feedback and it's good to know I'm on the right track!