Tiny sink, tiny bathroom. 2" cast iron right there. Any reason not to use rubber T?

[CanOfWorms]

I have a very small powder room that I want to put an even smaller sink into. There is a 2.5" outside diameter cast iron pipe right there running floor to cieling.
My first thought was to cut and put in a pvc drain T using no hubs. But that is 1 foot from the toilet at eye level. It would be unsightly and big.

Is there any reason I cannot use a rubber T like the one pictured below. I know it will also be ugly, but it will be smaller and I could probably get away with painting it white like the pipes.
I also put a little sketch of the corner.



Here is a sketch.

[CanOfWorms]

Update on this one. The line going down the wall is 2.5" outside diameter.

I looked up these fernco quick tees. Here is a link to the chart describing: http://www.fernco.com/plumbing/flexi...-ells#tabs-1-3

[jimbo]

Do you know if that cast iron pipe is a waste pipe? If it is a vent coming from the lower floors, you cannot put waste into it

[CanOfWorms]

Do you know if that cast iron pipe is a waste pipe? If it is a vent coming from the lower floors, you cannot put waste into it

Its not a vent pipe. It is on the bottom floor. I emailed Fernco they said the QT-200 will fit.

Any reason not to use the rubber T?

No plumbing code allows the rubber fittings.
Added by Terry Love 3/3/2013

[asktom]

It won't support the cast iron above it.

[CanOfWorms]

It looks like the pipe runs against the wall about as far away as the elbows protrude. It then does a 90 degree turn right above the sheet rock. The wall is a solid concrete wall.
I suppose a few U braces screwed into the wall would support it as long as they were very snug. I should also shim behind the pipe so it does not pinch in where I put the rubber T.
What do you think?

[hj]

"I" think it's a dumb idea, but I suppose you intend to use it anyway, so telling you that it is NOT the proper way to do it is useless. A PVC tee and No-Hub couplings will be EXACTLY the same size, look better, but would still NOT be proper since it appears this is a waste line, not a vent. If it is a waste line, you could be creating problems for yourself, since the new sink will NOT be vented.

[CanOfWorms]

I'm here for advice and value your expertise. If you say the rubber T is a bad idea I would not argue with you.

Venting: On the second floor there is a sink that feeds into a 1 and 1/2 that goes out the roof from there as a vent. That line comes down and becomes this line, so isn't it vented up there? It seems like most of the sinks connect to 2" iron pipes that vent out on roof and toilets connect to a different line. I've lived in the house for 7 years with constant high use and have never smelled sewer gas.
Also does it need to be vented if the sink is only is 12" from the waste line?
My slop sink isn't vented immediately.
Do they make PVC T street?

[asktom]

The venting situation is what HJ stated above may well cause you problems. You are wet venting between floors. The top floor sink will be fine but not the lower. When water comes down from above it will be pushing air. This may cause the water in the downstairs trap to slosh around, possibly enough to send some down the drain breaking the trap seal. If that happens there is nothing between your nose and your sewer. To do it right is a larger project than you envisioned.

They make street san tees, but they are only street on the bottom, you would still need a short hunk of pipe for the top.

[CanOfWorms]

OK. Got it venting ok for up top but two floors down it would create problems. I can imagine old pipes that may be slow to drain will make it even worse in that small sink two floors down
Taking that into consideration.
I have three thoughts: 1. Back flow valve?
2. More downward slope from sink rather than a horizontal run.
3. Using a 45 degree Tee instead of a rounded entry Tee
See the pic:

[jimbo]

1) wrong
2) wrong creates S-trap code violation
3) wrong code violation....must be sanitary Tee

Still violated wet vent codes

[CanOfWorms]

My first instinct is to say code shmode. : )>
But if I did not have to worry about code, would a horizontal run with a back flow preventer before the sanitary trap to the trick?

[asktom]

A check valve won't work and the other two approaches will just compound the problem, the trap could syphon. Code and physics require a vent before you tie into the waste line. The vent would need to either go through the roof or tie into another vent above the fixture that vent serves. Sorry, but that is the deal. Is there an existing toilet in this room? If it is plumbed correctly you may be able to tie into the toilet vent.

[CanOfWorms]

There is a toilet in the room. It is on the caddy corner from this. The waste line runs floor to cieling and goes up to the third floor where it connects to that toilet.
There is a squirrels nest of drains and such behind the washer, I suppose I could tie into that.

On another note, can I connect a shower waste drain to the 4 inch toilet line I mentioned? I have a clawfoot tub in the room behind this with no drain pipe. I want to connect to this 4" waste line.

[jadnashua]

EACH and EVERY fixture drain needs a vent. Once a pipe is used as a vent (or waste) its function CANNOT CHANGE! IOW, you can't make a drain a vent, and you can't make a vent a drain - they cannot be dual purpose (with very few exceptions, and then, only within the same bathroom). Sometimes, it's not easy, and you have to tear up more than you want to make it all work right. When your house was built, it may or may not have passed today's codes. Generally, if you do not touch it, it's grandfathered. But, as soon as you touch it, the part you touch must be brought up to today's codes. Over the years, materials and knowledge has increased, and what may have worked in some circumstances way back when, was found to be faulty thinking, and there were situations where it would fail to provide a safe environment. The codes are designed to keep you safe, and have things work...whether you get it inspected or not, the physics and realities still apply and you should make it pass.