I am doing the rough-in on a bathroom remodel (trying to save some money). It is actually 2 small bathrooms back to back that share a 2x6 common wall - sink, toilet, shower with the mirror image on the other side. Each fixture will share common venting/drainage with its mirror fixture (sink-sink, etc.) Here is what I want to know:
1)What vent/drain size for each shared set of fixtures. (e.g. each sink would have 1 1/4 trap, but since there are two, do I need a 2" drain and vent?) Same with shower/toilet?
2) Is a 3" stack vent adequate (no other fixture on this vent)?
3) Do I need a 3" or 4" main drain line to sewer (only a kitchen sink also on this line - no washers)?
4) The venting layout I can picture in my head, but I am a little confused about how to connect all the drains. (e.g. I will have 3 shared drains coming out of the bathroom [sinks, toilets, showers], at what point and how should I connect them all?
5) Can I use a 3-3-3 waste cross for the two shared toilets?
Thanks for your time! Anyone who can recommend a good book on the subject would be appreciated (all the stuff at home depot is for unclogging drains, not actual planning)

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Originally Posted by jessechenven

I am doing the rough-in on a bathroom remodel (trying to save some money). It is actually 2 small bathrooms back to back that share a 2x6 common wall - sink, toilet, shower with the mirror image on the other side. Each fixture will share common venting/drainage with its mirror fixture (sink-sink, etc.) Here is what I want to know:
1)What vent/drain size for each shared set of fixtures. (e.g. each sink would have 1 1/4 trap, but since there are two, do I need a 2" drain and vent?) Same with shower/toilet?
2) Is a 3" stack vent adequate (no other fixture on this vent)?
3) Do I need a 3" or 4" main drain line to sewer (only a kitchen sink also on this line - no washers)?
4) The venting layout I can picture in my head, but I am a little confused about how to connect all the drains. (e.g. I will have 3 shared drains coming out of the bathroom [sinks, toilets, showers], at what point and how should I connect them all?
5) Can I use a 3-3-3 waste cross for the two shared toilets?
Thanks for your time! Anyone who can recommend a good book on the subject would be appreciated (all the stuff at home depot is for unclogging drains, not actual planning)

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Hey Jesse,

(1) 2" drain and vent on the lavatorys. 2" on the shower drain. On the toilet, 4" if a basement rough in and 3" if a first floor rough in.
(2) The 2" lavatory vent will serve as a wet vent for your group unless you wish to tie the lavatories into the pipe coming out of the cross that picks up both toilets and wet vent the group through that.
(3) you failed to mention where this will be going down. 4" main in the basement, 3" if upstairs.
(4)If you can furnish me with a drawing, complete with wall and floor measurements, of the rooms, existing pipes and your fixture placements I will lay out the drainage for you according to the Standard Plumbing Code Book.
(5) You may use a cross,( 4" basement, 3" upstairs" to connect the toilets

The best books (three of them) can be ordered from the Audel Division of Howard W. Sams & Co. of Indianapolis, Ind. Or checked out at your local library. The set is called, The Plumbers and Pipefitters Library by Jules Oravetz, Sr. This set of books covers it al, in language you can understand.
Good luck, Tom

Hi, check out the attached layout of the bathroom. The house is one story, with a crawlspace. The only other line that exists is a 2" from the kitchen.
Jesse

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Originally Posted by jessechenven

Hi, check out the attached layout of the bathroom. The house is one story, with a crawlspace. The only other line that exists is a 2" from the kitchen.
Jesse

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Good morning Jesse,
Thank you for the detailed drawing of the fixture lay out. However before I can lay out a drainage system I have to have some place to drain it to and which direction to slope the pipes. Show me on the drawing where you plan on connecting the two bathrooms, the size and material of the main and which way it slopes. Will you be converting to PVC? From what? Plastic? Cast iron? At what point will you be tieing in the two bathroom groups?
I'll wait on your answer. Tom

Okay, here is a revised picture. It shows the red main outside the house. The main is ceramic, 80+ years old, with an ID of 4+". There is absolutely no plumbing in the bathroom now, I tore everything out and reframed it. I plan to run all DWV lines (including a new main vent stack) with ABS, which is permitted by code here in New Mexico. From the subfloor to the main outside is about a 3' drop over 8-10 feet. I would like to connect the two bathrooms right under the new 2x6 wall if possible, and then connect the 3 separate fixture drains (showers, WCs, sinks) before they head under the footing. The only other drain is a 2" galvanized kitchen drain in the upper left side of the drawing. I plan on connecting this to the new ABS stuff as they head out.
Thanks!

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Originally Posted by jessechenven

Okay, here is a revised picture. It shows the red main outside the house. The main is ceramic, 80+ years old, with an ID of 4+". There is absolutely no plumbing in the bathroom now, I tore everything out and reframed it. I plan to run all DWV lines (including a new main vent stack) with ABS, which is permitted by code here in New Mexico. From the subfloor to the main outside is about a 3' drop over 8-10 feet. I would like to connect the two bathrooms right under the new 2x6 wall if possible, and then connect the 3 separate fixture drains (showers, WCs, sinks) before they head under the footing. The only other drain is a 2" galvinized kitchen drain in the upper left side of the drawing. I plan on connecting this to the new ABS stuff as they head out.
Thanks!!

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Thanks Jesse'

I could make the layout much simpler if you would exchange places with the toilets and the showers. That way I could take one 3" vent off the lavatory cross and vent both bathrooms with just the one vent. I take it the terra-cotta sewer runs past the 2 X 6 wall so all you need is the two bathroom groups and the kitchen sink terminated just outside the house ready to tie to the sewer. Is there a reason you're using ABS instead of PVC? Tom

Hi Tom,
1)Switching the shower with the toilet would put it in the middle in an awkward place, so if I can get away without moving the shower, it would be best. I don't mind switching the sink and toilets though if that would help.
2)Yes, the terra cotta sewer starts right outside the exterior wall (I already removed all the old sewer pipes that ran out there), and goes west (left). So, I just need to terminate all the drains out there.
3)I've worked with ABS before, and it is cheap and easy to find out here (literally everyone uses it). But, I have nothing against PVC, I know it is supposed to be better.
NEW QUESTION: Not to get side tracked, but: I don't want to completely tear out the old 80' of terra cotta waste line running through the yard. But, it is old, and will eventually need to be replaced. Do they make any kind of plastic sleeve that I could slip inside of the existing pipe (which has an ID of 4"), rahter than running 80 new feet?
Thanks for all your help and advice,
Jesse

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Originally Posted by jessechenven

Hi Tom,
1)Switching the shower with the toilet would put it in the middle in an awkward place, so if I can get away without moving the shower, it would be best. I don't mind switching the sink and toilets though if that would help.
2)Yes, the terra cotta sewer starts right outside the exterior wall (I already removed all the old sewer pipes that ran out there), and goes west (left). So, I just need to terminate all the drains out there.
3)I've worked with ABS before, and it is cheap and easy to find out here (literally everyone uses it). But, I have nothing against PVC, I know it is supposed to be better.
NEW QUESTION: Not to get side tracked, but: I don't want to completely tear out the old 80' of terra cotta waste line running through the yard. But, it is old, and will eventually need to be replaced. Do they make any kind of plastic sleeve that I could slip inside of the existing pipe (which has an ID of 4"), rahter than running 80 new feet?
Thanks for all your help and advice,
Jesse

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OK Jesse,

Here's how I see it Your main will be 4". Your main vent will be 3" from the lavatory. The branches and the revent will be 2" with the exception of the toilet which will be 4" to the flange. Starting at the lavatory vent. Revent to the showers with a 3 X2 inverted tee on the main vent 4' off the floor. Lavs will be picked up with a 3 X 2 double drainage tee and drain into a 3 X 4 short sweep. The toilets will be picked up by a 4"double wye off the 4" main. The showers will be picked up by a 4 X 2 double combination wye and eighth bend. Just ahead and upstream from the combo you will place a 4 X 2 drainage tee on its back and come up 47 1/2" and elbo back into the inverted tee to vent the showers. The sink will tie into the 4" main by 45ing over to the main where it will be picked up by a 4 X 2 wye.
that oughta do it. Cheers, Tom