I have a house that has a half bath on the lower level I want to add a
shower. The only new problem I am faced with is this is a concrete floor, no
crawl space under this one. The sink drain is the closest drain and it goes
straight into the floor. This house is forty years old and is all cast
drains and vent with copper drain lines connecting to the cast ones, no PVC
here. I plan on just busting up the concrete to see what is there. Any one
ever done a job like this? Any input on what I might find would be a help, I
would like to know how deep the sink drain goes down before turning so I can
figure out if the shower will be flush with the floor or will I need to
raise it up?
My shower base is flush with the concrete floor. The drain and trap are
only a few inches below the bottom of the floor. The drain line now runs
under the floor (kitty corner) where it connects to the line that runs out
to the sewer. Toilet and sink both drain to the same location, fortunately,
there was a Tee available to connect the drain line. Obviously, I had to
bust up the floor in order to put in the shower drain line.
What you'll find will depend largely on how the fixtures are laid out
in relationship to each other and the main and any laterals. If the
sink is isolated and on a separate line, it quite likely isn't large
enough to handle a shower, too. If, otoh, it feeds into the lateral
servicing the toilet, that is probably adequate. Again, depending on
the geometry, it might be relatively easy to insert a tee for the
shower and go from that point to the main or lateral of adequate size.
The possibilities are almost innumerable. How deep also will depend on
the depth of the external sewer, the length of the run, how deep is the
frost line there, etc., etc., etc. You have a treasure hunt in front
you, undoubtedly... :) Although if you map out the overall plumbing
layout, you may be able to reasonably deduce the direction and location
of lines, particularly if you do know where the main line leaves the
house. With that, you could also probably make reasonable guesstimates
of line sizes and if you were to know the exit line depth perchance, of
the depth of lines there as well.
I broke up my basement slab with an electric jack hammer to expose the
drains underneath when I replaced the shower in my basement bath. The
original shower had no base. As far as I can tell, the drain was
installed when they poured the slab since the floor of the shower was
the slab itself. It sloped into a hole into which a standard sink
strainer was placed. I can't imagine it was a retrofit.
Anyway, I was able to expose the cast iron pipes under the floor and
removed the old drain pipes until I reached the Y connector. I then
used a rubber bushing to reduce the 4" cast pipe down to 2" for a PVC
Since you don't have a drain in the location of the shower, I'm
guessing you're going to have to bust up the floor enough to access the
connection from the sink to the main drain. At that point you may be
able to attach an adaptor to hook up both the shower and sink.
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