Could someone please tell me what is right or wrong. I have just
fitted a complete new soil stack and bathroom suite. At the moment the
only thing connected to the soil stack is the toilet. I now have to
tee in the bath and sink waste pipes.
Could someone tell me is it OK to tee the bath and sink waste into the
soil stack above the tee piece for the toilet or should it be below
It doesn't matter. What you must do, though, is properly vent both
fixtures. As long as the sink is less than 5' from the soil stack
(technically it's really the "stack vent" at that point), put the tee
in such a way that it runs horizontally directly to the sink trap,
with proper fall. The tub will require that you run a vent from the
tee for the tub trap, and terminate it 42" above the floor level back
into the stack vent. If you put the tub drain in above the toilet
tee, then the toilet should be similarly vented. There are some other
possible variables. Write back with more questions if you have them.
(BTW, guys, I'm writing this from my new place in Kosovo).
It is only a soil stack if it conveys soil more then 1 branch
interval (1 story), such as the second floor down to the first
and any vent above it is considerd a stack vent. Anything less would
be a vent stack.
But to answer your question if the toilet were to be tied into the
stack with a trap arm, anything at that level such as a tub trap would
also be stackvented by the same vent stack/stack vent as long as the
trap distances were met by your local/state code. The sink could be
piped to that level but would require a seperate vent, that could tie
back into that stack 6" above the flood rim of the sink.
"or" many codes allow the lav. sink to be tied into the stack above
the lower levels and not effect the venting, due to the fact that it
is only 1 DFU from the lav. and would fall into the highest fixture on
a stack catagory.
If this bathroom group is the only thing on this "stack" (technically a
stack is a soil or waste pipe which drains through at least one full story,
otherwise its just a soil or waste pipe) then all three fixtures may be tied
directly to the stack providing the fixtures are all tied in separately and
directly (at different levels) and the toilet is the lowest connection, and
none of the trap arms extend far enough to achieve one pipe diameter fall.
(i.e. 1 1/2" trap = 6 ft maximum @ 1/4" per foot grade) Using this
configuration is the simplest and does not require any additional venting.
This is called a vertically wet vented group, and is permitted at least by
the national plumbing code of canada.
You could also horizontally wet vent it, but that tends to get confusing,
and complicated for do it yourselfers, and would require additional vent
Journeyman Plumber/Gas fitter
BYRD Plumbing & Heating
(technically a stack is a soil or waste pipe which drains through at
least one full story, otherwise its just a soil or waste pipe)
Technically a stack is a general term for a soil, waste or vent pipe
which has a min. of 1 branch interval in height (equal to one-story in
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