I want to add a utility sink in my basement. The main stack goes into the basement concrete floor and out to the city sewer line. This stack runs through the attic, venting through the roof to the outdoors. Can I simply tap the drain from the sink directly into this stack without violating any major codes?

Klugeman...

You sure can cut into that stack without violating codes... but if this is a cast iron stack then you will need to proceed cautiously! Heck, even if it's PVC or ABS plastic pipes you need to be careful and support the weight of the stack using a RISER CLAMP (see picture) and some 2"x4" studs under the ears to support weight.

Let me know what kind of material we're talking about here so we can discuss fittings and what particular tools to use to cut into the stack.

You will want to plan on installing a 2" drain line (with full size 2" cleanout) and then can reduce to 1.5" drain and Ptrap for the utility sink.

You will also need to run a VENT for this sink (1.5" vent) and connect into a vent that is already in the basement... OR you may be able to install an air admittance valve (AAV) if they are allowed in your area.

You will need this vent so that any fixture that discharges waste PAST the sink drain will not SIPHON the trap and allow sewer gasses to escape and stink the place up (never mind health hazard).

Anyway, get back to us with more info. And answers to questions so we can help where we can... ;)

Let me know...

MARK

Hello.
Thanks for the answer! Actually, a few years ago, I cut out part of the CI pipe and patched in a PVC 4" pipe using a rubber Fernco coupling. I plan to locate the sink near this pipe and can cut into the PVC to add a Tee to accommodate the drain. I think I will have to add the AAV since there are no vents readily available near there. Can I get the AAV at Menards?

When I cut the CI pipe, I added the riser clamp up in the attic and made my own clamp in the basement to hold the pipe to the floor joist just as it comes through the first floor to the basement. I has held up.

If you see anything I've missed, please let me know!
Thanks!!

AAV should be available at Menard's or home depot!

And... although they sell fernco clamps to homeowners these are primarily made for underground plumbing transition connections so if you have a chance you may want to use a shielded clamp such as I have pictured below. This is a much stronger clamp and is correct in terms of plumbing code requirements!

You would order a 4" cast iron by 4" pvc mission style or proflex style clamp (these are trade names for shielded clamps).

Looks good otherwise... ;)

MARK

Thanks for the help. Its really good to be able to post a question and get real answers that are helpful!

We're glad to help... anytime!