Easy to move kitchen's soil stack?

[ypp]

We're planning a DIY kitchen remodel and have a question about moving the soil stack. Namely, is it easy to re-do the piping (provided we find the right size bends and fittings?)

Our existing kitchen sink sits under a window. There's a ledge behind the sink/under the window that is about 4" high and 4" deep - I posted a couple photos below. Currently, we have 4 inches of dead space behind our cabinets and we have an extra-deep countertop for the lenth of our kitchen.

We pulled off the ledge to see what was back there, as we'd like to get rid of this and move the cabinets back against the wall when we re-do the kitchen.

The soil stack from the kitchen sink is located inside this ledge. The top of the stack (when the pipe is parallel to the ground) is about 2" above the normal countertop height - it's directly under the hammer laying on the ledge in the photo below. The pipe runs to the right to get past the window, then makes a 90-degree turn to get back behind the wall, then goes up to the roof. We can't move the pipe back into the wall behind the sink, because it would require a complete cut through a load-bearing 2x4 that runs down from the window. What we'd like to do is move the new cabinets back against the wall, lower the soil stack a few inches to get it beneath a regular counter height, and then run it through the cabinet next to the sink and then back into the wall.

Does anyone see any problems with doing this? Anything we need to look out for? Or do we need to keep this goofy ledge (and therefore get a custom countertop, etc...) Thanks in advance for your thoughts!

[LazyPup]

Not only would you not be permitted to lower the horizontal section under the countertop, it appears that the current horizontal line would not meet code specs.

The Plumbing codes state that you may not install a horizontal vent until the vent is a minimum of 6" above the flood level rim of the highest fixture served by the vent, which in this case is the kitchen sink.

The Good news is that you can run the vent through the 2 x 4's on the outside wall.

A kitchen drain is required to be an 1-1/2" diameter pipe and the outside diameter of sched. 40 1-1/2" PVC or ABS is 1.90"

The code will permit drilling a hole up to 2" through a 2 x 4.

While the outside wall is a loadbearing wall, the center 2 x 4 under the window sill is not a load bearing 2 x 4.

you may drill a 2" hole through a loadbearing 2 x 4 if the stud is sistered with a second stud.

[ypp]

Lazypup, thanks much for your reply. I'm happy to hear the good news along with the bad!

The existing pipe is cast iron. We can't get at it to measure (not ready to totally demolish kitchen yet) but it appears to be 2.5-3 inches outside diameter.

Can we use a neoprene (sp?) fitting to go from the cast iron to PVC (and then another neoprene fitting to go back from PVC to cast iron once we've met up with the vertical vent in the wall next to the window?) Or is there another fitting that works better?

I guess we won't be able to get this to meet code, as we can't get 6 inches above the sink (we'd be in the window) but at least we won't be making things worse... Thanks for your help!

[LazyPup]

It is difficult to tell from the photograph but hopefully there is a basement or crawlspace under the kitchen floor where the pipes are accessible.

From the photo's it appears that the existing drain would be coming up on the right hand side of the center stud under the window.

If you have access from below I would suggest you reverse the end-waste kit on the kitchen sink, putting the trap on the left end. You could then run your new line up from below on the left side of the center stud, install a sanitary tee & stub out a waste arm to the trap.

Install a 'Street 1/8 bend" on the top of the tee and make a 45deg offset through the stud into the next stud bay where you can attach to the existing vent.

A Fernco fitting would be the correct method to connect PVC to the existing cast iron.

[ypp]

Thank you so much for your suggestions. Yes, we do have a basement below the kitchen and we have no qualms about ripping off the drywall to access these pipes, so hopefully this will go smoothly.

We only recently discovered this forum and it seems to be a wonderful place filled with great people and suggestions. I have a feeling we'll be visiting here a lot as we update our home! Thanks much!!