Reroute kitchen drain in ceiling of finished basement?

[lottia]

Our kitchen sink drains to the outside of the house where it is broken. Beyond the break, the existing pipe exits through our storm water system. Tunneling would be required to reroute this drain on the outside of the house and rejoin the main waste line. The first estimate we received was for $16K before tax!

Another option could be to reroute the drain from the kitchen sink to another interior drain. The least disruptive approach would be to access the space below the kitchen floor via a finished basement ceiling. This would require opening the ceiling for about 15', notching or drilling the joists, and running pipe to where it could turn 90 degrees, then run between joists to the target drain. The ceiling has an access panel near the target drain.

We know this route would work, because it follows the hot and cold water lines laid when the kitchen floor was open for a remodel in 2003.

Questions:
Would this approach be acceptable under the plumbing code?
How much slope is required for internal drain lines?
What diameter pipe is acceptable?
Is flexible pipe available that could be pushed through drilled joists?
If not, now deep a notch is allowed in a floor joist?
Are there other options we're not considering?

 

[Jadnashua]

Questions:
Would this approach be acceptable under the plumbing code?
As long as the drain is vented, and the lines run properly, yes, it could.
How much slope is required for internal drain lines?
The slope of a pipe less than 4" ID must be at least 0.25"/foot, and that may put it beneath the bottom of your ceiling if the run is long enough.
What diameter pipe is acceptable?
A kitchen drain generally needs to be 2".
Is flexible pipe available that could be pushed through drilled joists?
No, and it would collect the normal crud that usually goes down a kitchen sink...not pretty! If you do have to do this, usually, you end up using a bunch of shorter sections and couplings.
If not, now deep a notch is allowed in a floor joist?
This can be problematic...notches, while often done, are NOT allowed! A notch makes the whole joist the equivalent of what's left after you've notched it...the joist is a certain depth for a reason...making it shallower means compromising the strength. You can drill holes in joists, but you'll probably exceed the allowances if the drain run needs to go very far as you must maintain that slope or you'll get blockages.
Are there other options we're not considering?
Without seeing it, that's hard to say. One potential option would be to install a pit with a pump. Gravity is preferred, but a pump will work.

 

[Sponsor]

 

[lottia]

Questions:
Would this approach be acceptable under the plumbing code?
As long as the drain is vented, and the lines run properly, yes, it could.
How much slope is required for internal drain lines?
The slope of a pipe less than 4" ID must be at least 0.25"/foot, and that may put it beneath the bottom of your ceiling if the run is long enough.
What diameter pipe is acceptable?
A kitchen drain generally needs to be 2".
Is flexible pipe available that could be pushed through drilled joists?
No, and it would collect the normal crud that usually goes down a kitchen sink...not pretty! If you do have to do this, usually, you end up using a bunch of shorter sections and couplings.
If not, now deep a notch is allowed in a floor joist?
This can be problematic...notches, while often done, are NOT allowed! A notch makes the whole joist the equivalent of what's left after you've notched it...the joist is a certain depth for a reason...making it shallower means compromising the strength. You can drill holes in joists, but you'll probably exceed the allowances if the drain run needs to go very far as you must maintain that slope or you'll get blockages.
Are there other options we're not considering?
Without seeing it, that's hard to say. One potential option would be to install a pit with a pump. Gravity is preferred, but a pump will work.

Thanks for your reply. Kitchen sink has its own venting, as does the dishwasher, but I don't see a way to make the required fall inside the ceiling before we get to an interior drain.

So outdoors it is, I guess, but there are multiple obstacles.

1. This drain isn't on the city map, and someone had replaced at least part of the original 4" concrete with interior grade ABS, hence the breaks. So besides emptying into a stormwater drain, it's wildly out of code.
   
2. It's on the west side of the house, and the 6" main soil and waste line is on the south side and almost 8' lower.
3. The route to the main takes it through a very large rockery. And several trees are at risk whether we dig or tunnel.
   
4. Scoping has not been informative.

The pit & pump option would still require getting from the pit to our waste line.
Intercepting the waste line from a different direction would still involve a smaller rockery and might not be doable within code.

Grumph!