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Mike_Fox · Nov 6, 2011, 03:59 PM

I'm getting ready to rough in a new bathroom in my basement and I have a few questions. I would really appreciate any advice.

I will be breaking into an existing 4" sewer pipe under the floor. Does the connection to this pipe (3" from my new bathroom group) have to enter the existing pipe above center? I will be connecting with a 4X4X3 reducing wye.

Same question further up the line when the 2" drain pipe from the shower/lav connects to the 3" from the WC. This one will be wet venting.

I'm a bit concerned about depth. If all of the connections need to be above center I may run out of floor to bury my pipe in.

I will provide a scetch once I get a few basics out of the way.

Another question regarding closet flanges...

How do I install the toilet flange after I repour the floor? The ones I have seen a meant to go outside the 3" pipe that would be sticking up. I do not know how thick my floor will be once I level and tile. It seems like I might have to chip away some of the new floor to get the flange over the pipe after I level and tile. Am I missing something?

Thanks in adavance,

Mike

puffmugs · Nov 6, 2011, 08:06 PM

My code calls for 1/8" pitch per foot for 1 1/2 and 2" pipe. Some places do not allow 1 1/2 pipe underground and 1/4" to the foot for 3"pipe. For a 3" toilet pipe they make a a styrofoam or plastic cover to go over the 3"pipe and you just bust it out after the floor is poured and slip the 3" female flange on the pipe with the space created by the cover and secure the flange to the floor. If you are using PVC a trick that I use that is not considered legal but works great is use a 3 by 4 ell on the 3" underground and bring 4" thru floor for toilet, after floor is poured cut 4" off level with floor and slip a 3" female flange into 4" pipe, makes a very secure job to set the toilet on.

Mike_Fox · Nov 6, 2011, 10:49 PM

puffmugs · Nov 7, 2011, 05:46 PM

Codes are different everywhere, according to code in my area when you wet vent, the 3x2 wye going to the lav and shower must come off from the 3" horizontal branch going to the toilet, instead of the tee on the veritcal riser to the toilet. This will also save you some depth problems,otherwise your drawing is is fine. Good Luck with your project.

massplumber2008 · Nov 7, 2011, 06:38 PM

I agree with puffmugs... take the wet vent off the horizontal being sure to roll it above the center line. You also don't need to increase the toilet from 3" to 4" (unless your code states otherwise, of course)... 3" is fine for the toilet, lav., and floor drain.

I also see that you reduced the wet vent back to 1.5" at the lavatory. Here, the wet vent must remain a 2" vent all the way until it connects into a 2" or larger vent or goes out the roof full-size 2".

Finally, in my area and most that I know of, you want 1/4" pitch per foot of pipe for 1.5", 2" and 3" (1/8" per foot for 4" and larger), but again you want to check local requirements as codes definitely differ region to region, OK?

Otherwise, all else looks good!

Mark

PS: Where did you get the pipe drawing stuff... nice?

Mike_Fox · Nov 8, 2011, 05:55 PM

Thanks for the feedback.

I have a few more specific commments/questions...

Just to confirm that joint 1 is OK to be attached near center because there is no venting going on but joint 2 needs to be more above center because it is wet venting. Did I get this right?

I do understand that everything has to slope 1/4" per foot.

Are my pipe sizes correct? I sized the lav/floor drain pipe at 2" because it is also the vent but then I sized the vent itself at 1 1/2". The smaller vwent pipe will help me out in the ceiling.

I love the 4" X 3" closet elbow with the flange inside! Thanks puffmugs!!

I think I will move the shower/lav drain to connect to the horizontal pipe. It will definitely help reduce depth. I just thought that the flow from the shower might help prevent clogs because the wife wants a low flow toilet.

I think I will need to keep the shower vent because it is near 10ft from the shower trap to the lav vent. Unfortunately my bathroom wraps around the chimney so I don't have much option to shortcut!

Will the shower drain fit inside the 2" drain pipe or do I need to accommodate for that when I re-pour the floor?

Sorry I'm an engineer and it makes me a bit obsessed with details. Lol

Thanks again for the great input.

Mike_Fox · Nov 8, 2011, 05:59 PM

Not sure why my pics keep getting cut off.

Joint 1 is at the bottom LH of the first pic.

I modeled the pipes in a mechanical design software called Solidworks. I got the 3d models on a free CD from Charlotte pipe & Foundry.

You are probably thinking that I have too much time on my hands but its not true. Lol. I just want to get this right.

puffmugs · Nov 8, 2011, 10:12 PM

You can use the same plastic or styroform cap for the shower that you would have used for toilet, or you can just wrap the 2" pipe above the trap with cardboard or make a small wood frame with sand in it around the pipe. The type of drain you use depends on the type of shower you use. If you use a tile shower with a pan you would use a 2" female shower dish over the 2" pipe. If you use a fiberglass unit you would use a shower drain in the unit that drops over the 2" pipe, but you still need a space for the nut on the bottom of strainer to fit into, either way you need a space in the cement for the shower drain. In this area the 1 1/2" vent is OK, but alot of other areas require 2", 1 1/2" vent will work but will not pass inspection in some places if you are getting one. Just to remind you it is important to take the other fixtures off the 3" horizontal branch going to the toilet, then if you want to, use the 3x4 ell on the end of the branch going to the toilet.