Minneapolis Plumbing Question- Min Drain Size

10 Replies

This is a pretty specific question, but can someone tell me the minimum drain size required for a kitchen sink in Minneapolis? We're renovating a kitchen and had one plumber tell us 2.0", while my code research (section 420.3) tells me it's 1.5". 

Our drain is currently 1.5", and I don't want to have to tear into the wall if it's not necessary and I don't want to have any surprises me it comes to the final inspection for our building permit. I also have trouble internallizing pulling a permit and hiring out the work for a simple sink hookup. 

Also, if anyone has any plumber recommendations  in the area, I'd appreciate them. Thanks!

1 1/2" is code to the T, then 2" for the stack. 2 1/2 if the line is over 4 ft horizontal before it goes vertical. Don't tear it out unless the city is asking you to. If it's old, it's likely not vented either, so more issues. Don't replace it unless it's broken or you're forced to

@Joseph Lee the plumbing inspector is always your best resource for plumbing questions.  Some are more strict, others may be willing to take practicality into consideration.  If you are remodeling the kitchen you should have pulled a separate plumbing permit so they will be out to look at it one way or another.  Also better to do it now than have problems on a buyer inspection or a required repair on the truth in housing.

As @Todd Dexheimer mentioned the drain size should be 1.5".  The plumber could be old school and could be referring to the OD size of the pipe.  I have had a couple people call 1.5" pvc 2" pipe.  Your vent is likely going to be your biggest issue on an old house.  It should be vented properly which is either to run it through the roof or you can tie it back into a main stack.  This is a common problem on old houses and may be a big headache depending what is above the kitchen.  I have gotten away with vent caps at times but tearing apart the wall now will be easier than after your kitchen cabinets are installed.

Good luck!

Hey @Todd Dexheimer and @John Woodrich , thanks for the feedback. Old post, yes, but still an open item...haha. We've been dragging our feet on completing the finishing work (we're living in the unit right now, so we have the luxury of time), so we haven't had the building inspection yet.  The good news is that the drain is vented, and we're 1.5" to the T, so I'm hoping we don't have problems. My plan is to go into the building inspection as-is and if we get called on it, well, we'll approach it then.

John, you're 100% right in that we should have pulled a permit. Not to go off on too long a tangent, but I struggle with the fact that we're supposed to. We did pull a building permit and had an electrical permit pulled for the electrical work done in the kitchen, but didn't pull a plumbing permit, and I'll give you my reasoning for why- since it's a duplex in Mpls, even though we own the property and live in it, we're not able to pull any permits outside of a building permit. Everything else has to be pulled by a licensed contractor (with plumbers, they have to be licensed with the city, not just the state). The only plumbing work done was replacing the sink, so hooking up a new fixture and replacing the shoddy drain with a new PVC drain. Although it's the letter of the law, I still struggle with hiring a plumber for $300-$400 to pull a permit and simply hook up a drain and supply lines. Do either of you feel like this is just the cost of business and something that we need to do no matter how crazy it seems or something that we can get by with in small instances like this? If you're not willing to say something on a public forum about not following the law of the land in Minneapolis, I totally understand, but wanted to pose the question.

@Joseph Lee in regards to pulling the permit - I would first be surprised if the building inspector doesn't ask you about the plumbing permit.  Hopefully he does his job and gets out.  I haven't completed any plumbing upgrades in Mpls, only repairs so I haven't gone through the permit process on the plumbing side.  I thought the homeowner could pull a plumbing permit so long as they are living or intend to live in the property however Mpls may have further restrictions.

In my first few years of investing I operated under your thoughts - skipping a permit shouldn't matter, I know what I am doing and it won't get caught.  We learned the hard way on one flip back in the day and one plumbing inspector thought we did a lot of work we didn't do so we had to have a licensed plumber update areas of the house which were not touched to bring to current code.  That cost us around $5k of profit on a flip which was already active contingent.

At some point I realized if I want to make this a business I need to operate under the rules and not cut corners.  It does cost more but it does give you some piece of mind along with the future owners and inspectors when they see the permit history.  I am actually working on a house that I will move into, we are doing the normal kitchen, baths, etc.  I was planning on rewiring the kitchen myself as I can pull permits as the homeowner.  Now I am debating on just hiring it out to keep my relationship with my electrician going and so I don't have to deal with the hassles of meeting inspectors.

My mindset on this has taken a complete flip.  I personally don't understand why we have to pull permits for each sink install but the code requires you to update your system to code when you start working on it.  So to follow the rules you either have to leave it alone or not touch it.  The dumb part is that if you had a leak or corroded piping and had to replace the drain, it would be considered a repair and you wouldn't have to pull a permit....  Maybe that will help give you a reason around it.

The system may not make sense but it is there to protect everyone.  

Im a master plumber in Mn and i also have my masters in mpls and st.paul .

You can message me plumbing questions and i can help you out.

When it comes to doing plumbing for people i am typically overwelmed with work....

No guarantees on that end.

on the new plumbing code the waste pipe on the bottom side of a tee has to be 2"

The side inlet of the tee that goes to the trap can be 11/2 

And the upper part of the tee (the vent ) can be 11/2

Inspectors may "grandfather" things in at times But mpls/st.paul tend to be more strict 

@Alex Breuer tried sending you a PM but I don't know if it went through.  I'll be making a career change in 2 years and plumber is on the short list.  If I could pick your brain about the job that would be great!

I fell off the face of the earth a bit on this one, but @John Woodrich , thanks for the mindset insight. That's very helpful and (I think) the best way to look at it. If you wouldn't want your Fortune 500 employer to knowingly skate rules, your own business shouldn't either. Again, very good perspective- thank you.

@Alex Breuer , thanks for the offer! As a layman, reading and interpreting the code is...difficult to say the least. If I have any more questions, I'll reach out.

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