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Valiant422

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whats the minimum acceptable diameter for pipe for a toilet?

I want to put one upstairs, and will probably run 2 drains, one for a shower, and sink, the other for the toilet.

The only wall I can drop it through is a 2X4 wall, so is 2" ok?

also, should I add a vent for this, or is the one in the house acceptable?

Thanks in Advance :toothy4:
 
I would think you would want to go as big as you can even if it Menes building a box around the pipe.as far as avent I'm sure you are going to need it.I'm not a plumber but what i have dun i never had a problem with it..2" is good for the sink and shower.
 
I'd be hesitant to run less than 3" for anything that will see solids. Not sure on running a vent for that pipe. It's been a while since I've done anything but fix what's already there.
 
I've seen two inch turds*, so two inch is out. Go to your local home depot or lowes and ask their expert, so a) it will work and b) you'll be in code just in case there is ever an inspection. I think waste out is 4 inches. You must have a vent or it will not drain properly.




* I am a teacher, and have had to go in and flush when the kids come back out of the restroom running from the "turd monster" seems to be some sort of contest to see who can leave the biggest turd, IDK!
 
yes, you need a vent. 3" minimum for a toilet...
Plumbers claim that you can plumb a bathroom no matter where you put it. But the farther you locate the bathroom from your home’s main waste line, the more problems you’ll encounter. The main waste line is a 3- or 4-in. dia. pipe called a “soil stack” when it runs vertically inside the house, and a “building drain” when it runs horizontally underground. On the main floor, it’ll be enclosed inside finished walls, but you can usually locate it by looking in the attic or basement or on top of the roof, where it exits to open air. You’ll have to attach at minimum a 3-in. dia. waste line from your new toilet to this main waste line. The shorter the run, the better, so you don’t have to break into as many walls, floors and ceilings. In extreme cases, you may have to box in a portion of a ceiling for a drainpipe.
 
3" is minimum. Normally you can cut out 4" of the top and bottom wall plate to run a 3" line. Shower drains are 2" and sinks are 1-1/2" which on a bath sink are reduced to 1-1/4" at the sink hookup. A vent pipe is required within 6 horizonal feet of a drain to prevent suction from sucking the water out of a trap and allowing sewer gas into the house.
While staying at a B+B in Stratford on Avon (England) I saw a toilet which the owners had installed to expand their bedroom capacity that had a mulcher or something like a disposal behind the toilet that ground up anything that was flushed and the output line to the sewer was a standard 3/4" copper pipe. Very ingenious way to add a bath anywhere in a house without having to run a 3" line. Check it out

http://www.saniflo.com/SANIGRIND.aspx



Hope this helps, Jim
 
well there is nothing upstairs now, so it will all be new.

a 3" pipe should squeeze in a 2X4 wall, I'm just worried about cutting the sill/top plates.

the existing vent is 1.5"
 
422: This is a car site but by golly there are people on here that do that kind of work to support their habits and i'm one of em so here ya go. At the top floor, or the first toilet in line, the code says that a 3" schedule 40 PVC is acceptable but when you pick up another toilet in that line you then have to bump that size to 4" at the second toilet. There is no need to place a trap under the toilet in that line as the toilet itself is traped. You will need a trap in the 1.5" line under the lavatory. Be sure and run a vent out the roof or it will never flow right. NEVER stub the vent into the attic and leave it there. If you do and your lucky all you will ever realize is the smell of turds but if your unlucky you will notice an explosion of trapped gases. If the 3" pipe is larger than your wall simply fir out one side of it and resheetrock. Place a metal guard across the plates where the pipe runs through them so as not to drive a nail where it will give you trouble later. If your lower bathroom only has a 3" line now you should replace it at that point with a 4" in the remainder of that line. You might get by ok if it only a 3" now, who knows but as i explained this is code in our area. Hope this helps.
Small Block
 
A toilet drain doesn't go in a wall anyway. 4 inch through the floor. The "closet" dimension for a toilet drain is from wall to back edge of hole, not to the center of the hole.
 
For clarification, Redfish, in a residential situation as we're dealing with here you are correct however in many commercial installations they do go in the wall with a wall mounted stool but i think he's refering to the drop that will run down through the wall below as he heads for the existing line at the othet tyin. His closet flange will be mounted in the floor, That is correct. On to the other issues. 422, measure out from the wall/sheetrock 12 " for the center of your hole in the floor unless your useing a 10" unit. Be sure and miss the joist below.
Small Block
 
3 inch PVC should work fine for you. You will need another vent through the roof for the stack. I would have to use 4" in my house though, just to handle the load. :toothy10:
 
Liscensed 30 years so I know what I'm talking about.You need a three inch drain and you can stub three inch up and the same flange that glues inside 4inch will glue over 3 inch . rough in is 12 and a half inches from the wall to center of stub up with half inch Sheetrock wall covering. If you need any advice pm me and I will give you a phone number. I've been plumbing residential new const since 1980
 
thank you for the advise guys

while the sanigrinder thing is a cool idea, I don't have room for it.

looks like I'll be knocking out some plaster or boxing in a pipe, maybe I'll run it outside the house, and well insulate it so my poo won't freeze!

Its a tight space, and a pain to go all the way down stairs to do business in the middle of the night.


Actually come to think of it, the chimney has plenty of space in it, and runs close to where I want to put the 2nd bathroom. Its a faux chimney as the flu is a prefab unit inside a decorative housing.

Does the vent that goes through the roof have to be 3" also?
 
Good info, there.

My worst nightmare would be running a pipe too small and some visitor launching a U-boat.
 
Small Block said:
422: This is a car site but by golly there are people on here that do that kind of work to support their habits and i'm one of em so here ya go. At the top floor, or the first toilet in line, the code says that a 3" schedule 40 PVC is acceptable but when you pick up another toilet in that line you then have to bump that size to 4" at the second toilet. There is no need to place a trap under the toilet in that line as the toilet itself is traped. You will need a trap in the 1.5" line under the lavatory. Be sure and run a vent out the roof or it will never flow right. NEVER stub the vent into the attic and leave it there. If you do and your lucky all you will ever realize is the smell of turds but if your unlucky you will notice an explosion of trapped gases. If the 3" pipe is larger than your wall simply fir out one side of it and resheetrock. Place a metal guard across the plates where the pipe runs through them so as not to drive a nail where it will give you trouble later. If your lower bathroom only has a 3" line now you should replace it at that point with a 4" in the remainder of that line. You might get by ok if it only a 3" now, who knows but as i explained this is code in our area. Hope this helps.
Small Block
Click to expand...
New IRC lets you pick up 3 commodes on a 3 inch line they only flush 1.6 gallons at a time. Thats International Residential Code. IBC Building code approves it too. I would try to shoot across the attic and revent if possible. One 2 inch vent can handle a healthy fixture count if not ,terminate in attic with a quallity air admittance valve like Studor. Penetrating old roofs is asking for trouble
 
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