Is this example to code? Vent question

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Canada_DIY_Plumber

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I'm going through some articles to find my rough-in heights for a 36" tall kitchen sink and vanity. It seems like 16" off the floor will work for both.
But in the process I came across this article and I'm confused about why they ran their drain like they did.
https://upgradedhome.com/what-is-the-rough-in-height-for-sink-drains/

Wouldn't it have been more normal to just use a san-tee to connect to the vent stack? Doesn't this risk creating a siphon? Are you allowed to have a vertical drain section before you vent?

rough-in-sink-drain-wrong.jpg
 

Terry

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sink_dw.jpg


The trap arm comes off of a santee.
A kitchen sink must have an accessible cleanout.
2" for the waste, 1.5" for the vent and for the p-trap.

A 10" deep sink should get a 16" rough-in if you're using a disposer.
 

Canada_DIY_Plumber

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Thanks all. Glad I have reached the DIY stage where I can pick-up on certain obvious mistakes.

My rough-in is a little tricky and I don't know if it will be to code. I have two sinks back to back sharing one 2" drain. One is a lav (vanity) sink and one is a kitchenette sink. There will be no garbage disposal on the kitchenette sink (I'm on septic and I don't like putting all that extra stuff down the pipe.)

My plan is to use a 1.5" dual fixture fitting at 16" height. If I can't find a dual fixture fitting here in Canada, I will go with a san-tee cross.
 

wwhitney

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Since lavs and kitchen sinks are often roughed in at different heights, using stacked san-tees would typically be better. Both US major codes would allow that short vertical wet vent, not sure about your code but seems likely.

If you want to do it with separate san-tees and no wet venting, just have two parallel vertical segments for a a few feet. Below both san-tees, the drains can combine with a wye and a 45; and at 6" above both sink flood rims, the vents can also combine with a wye and a 45.

Cheers, Wayne
 

Canada_DIY_Plumber

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Stacked san-tees would be way better because then I don't need to cut out the existing 2" cleanout and san-tee for the lav which was already in place and is well positioned. They will be tricky to cut out and replace due to a lack of clean pipe length and stud locations. I can just cut out a section of the 1.5" vent and stack a san-tee in there for the kitchen sink.

36" counter height - 1" for the counter - 9" bowl depth - 1" for the connection means my max height off the floor would be 25". I won't have a problem getting to 20" or below if I stack them (and 16" if I didn't stack.)

At this point, I'm trying to be more pragmatic vs following code to the letter. Work won't be inspected. This drain is part of a wet-vent for a water closet. There used to be a tub that was also part of this wet vent but I moved that over to a 2" drain shared with a washing machine. I'm OK on total DFUs sharing this 2" pipe (two sinks) but I'm pretty sure that I'm not actually allowed to drain a kitchen sink into a wet vent for a water closet.

However, my other option was a lot of jackhammering and digging and then leaving two more ferncos buried 2' underground. I figured that allowing this sink (a small kitchen sink in a guest area of the house) to share the drain with the lav is not the worst offense in the world and likely won't have any practical negative impact and will probably be a more reliable system in the long run.
 

wwhitney

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I can just cut out a section of the 1.5" vent and stack a san-tee in there for the kitchen sink.
One of the US codes would require a 2" drain for the kitchen sink starting at the san-tee; the other would allow a 1.5" drain. So I suggest checking your code on whether the drain between the san-tees would be need to be 2" instead of 1.5"

This drain is part of a wet-vent for a water closet.
Interestingly, for both US codes, that would be a deal breaker for adding the kitchen sink to the drain; the kitchen sink would have to come in downstream of the WC. Horizontal wet venting is limited to bathroom fixtures in those codes, so as soon as the kitchen sink joins in, the wet venting has to stop.

However, the one Canadian code I looked at (Ontario, I think) had an allowance for 2 DFUs to drain through the wet vent from other fixtures. So if your code does as well, you can add the kitchen sink upstream of the WC, if nothing else is draining through.

Cheers, Wayne
 

DIYorBust

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That code would have saved me a lot of trouble lately. It's hard to imagine this being a problem in a small building, maybe in a big building.
 

Canada_DIY_Plumber

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Every province in Canada has their own code but I believe they all follow the national code fairly closely. I was trying to think about why it is the code... one thought is that kitchen drain waste may be more likely to clog the wet vent vs what runs down a tub or lav. That's not an entirely invalid concern and is one of the reasons why I will be avoiding a garburator.
 

Jeff H Young

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Canada DIY plumber, many codes don't make sense . and many do. its political often
 

Reach4

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Canada DIY plumber, many codes dont make sence . and many do. its political often
My favorite difference with Canadian codes is they permit traps for standpipes and kitchens to be below the floor. That kitchen trap below the floor seems particularly nice in that it can permit islands to use simple real venting vs loops or AAVs.

Based on a past posting, it seems that the trap below an island is permitted at least one place in Texas.
 

Jeff H Young

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yes Reach 4 I remember the Texas kitchen trap below floor. never seen that before
 
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