pipetree
New Member
I have two water closets back to back, into a 3" stack, one floor, stack straight through roof is this acceptable.
2006 ipc
- Thread starter pipetree
- Start date
Help Support Plumbing Forums:
Dan,
I believe it is. I am in North Carolina but we use the International Plumbing Code (with NC Amendments) and if neither fixture uses a pumping action such as a sump pump or washing machine it is acceptable. I am not sure if New York has amendments that would negate this but I believe you are OK. It is really just the same as using a cross between two lavatories in the same bathroom wall. Check with your local code official or get a copy of the plumbing code and make sure but sounds good to me.
I believe it is. I am in North Carolina but we use the International Plumbing Code (with NC Amendments) and if neither fixture uses a pumping action such as a sump pump or washing machine it is acceptable. I am not sure if New York has amendments that would negate this but I believe you are OK. It is really just the same as using a cross between two lavatories in the same bathroom wall. Check with your local code official or get a copy of the plumbing code and make sure but sounds good to me.
This question jangled some memory bells in my head. So I looked it up.
Florida Plumbing Code is based on International Plumbing Code, so I am assuming that IPC reads the same as Florida Plumbing Code, which is what I will quote from.
706.3 (Snip non relevant wording)Double sanitary tee patterns shall not receive the discharge of back-to-back water closets and fixtures or appliances with pumping action discharge.
Exception: Back-to-back water closet connections to double sanitary tees shall be permitted where the horizontal developed length between the outlet of the water closet and the connection to the double sanitary tee pattern is 18 inches (457 mm) or greater.
So, if I read the code correctly, the answer is No, with the one noted exception. Plus, I think that this is bad plumbing practice anyway.
Florida Plumbing Code is based on International Plumbing Code, so I am assuming that IPC reads the same as Florida Plumbing Code, which is what I will quote from.
706.3 (Snip non relevant wording)Double sanitary tee patterns shall not receive the discharge of back-to-back water closets and fixtures or appliances with pumping action discharge.
Exception: Back-to-back water closet connections to double sanitary tees shall be permitted where the horizontal developed length between the outlet of the water closet and the connection to the double sanitary tee pattern is 18 inches (457 mm) or greater.
So, if I read the code correctly, the answer is No, with the one noted exception. Plus, I think that this is bad plumbing practice anyway.
phish,
i will check my code book in morning. Will be curios to see if our are the same. I have not looked at that passage for some time, but my guess is you are correct. I am curious why you think it would be bad plumbing practice. I have never plumbed that way myself but in case i am ever tempted i would be appreciative of any realworld problems you may have seen from doing 2 toilets this way. I am also curious what 18" would do to make this acceptable to the code authorities. I will keep you posted on NC version of IPC.
Pat
i will check my code book in morning. Will be curios to see if our are the same. I have not looked at that passage for some time, but my guess is you are correct. I am curious why you think it would be bad plumbing practice. I have never plumbed that way myself but in case i am ever tempted i would be appreciative of any realworld problems you may have seen from doing 2 toilets this way. I am also curious what 18" would do to make this acceptable to the code authorities. I will keep you posted on NC version of IPC.
Pat
I think that the concern the writers of the code have is that waste and water can (and will) jump across the double sanitary tee and backwash into the drain line for the other fixture. I believe that the thought is that with 18 inches or more of pipe in between the water closet and the sancross, the water and waste will slow down enough that it won't happen.
My personal issue with sancrosses and twinells comes from my own very bad experiences with them. Years ago, as a project foreman, my project manager loved twinells on apartment building undergrounds. He would have me tun the main drain line down the center of the buildings, with bathrooms and other drains on either side. The front and the back of the buildings were mirror images of eachother, so we would turn a wye up and use a twinell on top of that to catch the drains. The piping on each side of the main drain was the same, and this was a major time saver.
The only problem is, if there is a clog in that main drain line, and you attempt to snake it out from on of the branches, 9.9 times out of 10 the snake will jump across the twinell (same would happen with a cross) and go into the other unit. After a couple of these incidents, I started insisting on running the main drain out of the end of the building and installing a cleanout there, so that it was much easier to clean the main drain.
The last job that I did for him, he designed using a twinell in the overhead drainage to catch two back to back bathrooms. One of these units piped this way got a clog past the twinell, and try as I might, I could not get a snake to make the turn. Long story short, in an occupied unit, I had to cut out a sizable chunk of ceiling, and cut into the piping to clear the clog. Right there, with urine and feces running down my arm, I decided that I don't like twinells, and their use is bad plumbing practice.
My personal issue with sancrosses and twinells comes from my own very bad experiences with them. Years ago, as a project foreman, my project manager loved twinells on apartment building undergrounds. He would have me tun the main drain line down the center of the buildings, with bathrooms and other drains on either side. The front and the back of the buildings were mirror images of eachother, so we would turn a wye up and use a twinell on top of that to catch the drains. The piping on each side of the main drain was the same, and this was a major time saver.
The only problem is, if there is a clog in that main drain line, and you attempt to snake it out from on of the branches, 9.9 times out of 10 the snake will jump across the twinell (same would happen with a cross) and go into the other unit. After a couple of these incidents, I started insisting on running the main drain out of the end of the building and installing a cleanout there, so that it was much easier to clean the main drain.
The last job that I did for him, he designed using a twinell in the overhead drainage to catch two back to back bathrooms. One of these units piped this way got a clog past the twinell, and try as I might, I could not get a snake to make the turn. Long story short, in an occupied unit, I had to cut out a sizable chunk of ceiling, and cut into the piping to clear the clog. Right there, with urine and feces running down my arm, I decided that I don't like twinells, and their use is bad plumbing practice.
phish,
you know, in this industry every idiot has the answers and never listens to anybody. I always promised myself that I would ask every more experienced plumber I met for his tips and tricks and it has served me well to not be a young punk know it all. Thank you for your advice... very good reasoning and I appreciate it. I love to suck up info like this. I have only been plumbing 12 years and in my opinion I know a lot but am still a baby in industry. I always get good info from your posts. Keep em coming. Patrick
you know, in this industry every idiot has the answers and never listens to anybody. I always promised myself that I would ask every more experienced plumber I met for his tips and tricks and it has served me well to not be a young punk know it all. Thank you for your advice... very good reasoning and I appreciate it. I love to suck up info like this. I have only been plumbing 12 years and in my opinion I know a lot but am still a baby in industry. I always get good info from your posts. Keep em coming. Patrick
Now you gone and done it. Ol' Phish's head is going to be so swollen that he won't fit through the front door! 
