Dave wrote:

Hello again,

sorry if I'm not describing the situation very well. The pipes are
cast iron, according to the plumber, and it is a 1.5" pipe (internal
diameter) that is not fitting very well into it's T-section, but that
is behind a rotten stud (2X4) and I really can't see that part. It
goes up to a vent however, and down to the drain, so I am guessing it
has to be a T-section at that particular spot. The home warranty
people denied the claim until I can give the plumber access to the
troubled spot, and since it's against the outside wall of the house
that's where he wants "access" to be gained. Consequently I am having
to take down steel siding (on the outside wall of the kitchen, next
to the back door) and cut a hole to expose the troubled area,. About
halfway through at his point. Thanks for your interest. Will
definitely update as progress is made.
Take it easy...

Dave

Thanks. That I can picture. I had basically the same situation -- at least
in regard to the vertical cast iron pipe being in the wall behind the sink,
and that being an exterior wall with metal siding and next to a door. The
vertical cast iron pipe in my case was a 4-inch stack that went down to the
drain and up through the roof as a vent. An upstairs bathroom and toilet
also drained into the same 4-inch cast iron stack. Being old and cast iron,
the stack itself had rusted out and was leaking inside the wall. In your
case, the vertical pipe may be 4-inch or maybe 1.5 inches, depending on what
it's function is. If you have a 1.5 inch vertical pipe (drain and vent),
that's easier to work with than the 4-inch pipe. Where the horizontal pipe
goes into the vertical pipe, it is probably leaded into a "Y" fitting that
you can't quite see.

I had two construction-type people who I know doing the work and they did
the whole job. In my case, about 6 or 7 feet of the 4-inch cast iron stack
had to be replaced -- from a point above the sink and behind a wall cabinet
down through the floor with a few fittings to tie into the main 4-inch
stack/drain in the basement. So, it was a complicated job that required
carpentry, construction, and plumbing skills.

One of the two guys I used knew how to carefully un-snap and remove the
metal siding pieces between the door and the edge of the house and mark them
and then was able to re-use the same siding and put it back in place. He
knew the terminology -- something about J-channels or something like that --
and he said there is a special little pry tool that is made for carefully
prying off the old metal siding (although he was able to do without the
tool). I had my doubts about whether taking the old siding off and
re-using it would work, but he was able to do that and the finished product
turned out great. That meant that I didn't have to worry about trying to
match the rest of the siding on the back wall when the siding went back up.

Like you, the best way to access my job was from the outside. Once the wall
was completely opened up from the outside, they were able to cut out the bad
section of 4-inch cast iron stack and replace it with 4-inch PVC. They used
a rubber fitting, known as a Fernco (brand name) to connect the 4-inch PVC
to the 4-inch cast iron. They used an angle grinder to cut off the old cast
iron pipe.

Due to all that was involved, it took the two guys about a day and a half to
do the whole job and get everything back together.

One little caution -- be careful when cutting the hole on the back wall to
see the pipes. By that, I mean to be careful that there are no electric
wires in the wall that may get accidentally cut.