Dry venting 6" above Clarification Please

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ARC

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Hi and thanks. I just need clarification on the UPC dry vent 6" horizontal rule, please.

I have a CI stack in a 1916 house with a side vent at about 36" above the floor. Not code compliant with the current MN UPC code for the vanity that was attached. I'm moving the vanity to the other side of the room and venting it separately, BUT connecting the drain to the main CI stack. For the 36" vent hole I want to connect the alcove tub/shower, and a utility sink in the basement (that was previously connected). The toilet is wet vented since it's within about 1' of the stack.

Question 1. Does code 905.3 UPC mean as long as the vanity has a separate vent, it's fine that it's connected/drains to a stack that has another dry vent at 36"? Or since it's connected to the drain system it's considered a fixture that is less than the minimum 6"? As I read the code (below) it's fine to have the drain tie into the drain of the shower then into the stack since the vanity has its own vent. Please confirm.

Question #2: If this works can do I use a 1.5" wye for the utility sink and shower dry vent connection, or is just a regular T fine? (highlighted in red on plumbing diagram)

If the 36" vent into the stack doesn't work I can tie into the new 1.5" vent for the vanity if needed.

Thanks so much.

905.3 Vent Pipe Rise

Unless prohibited by structural conditions, each vent shall rise vertically to a point not less than 6 inches (152 mm) above the flood-level rim of the fixture served before offsetting horizontally, and where two or more vent pipes converge, each such vent pipe shall rise to a point not less than 6 inches (152 mm) in height above the flood- level rim of the plumbing fixture it serves before being connected to any other vent. Vents less than 6 inches (152 mm) above the flood-level rim of the fixture shall be installed with approved drainage fittings, material, and grade to the drain.

Bathroom Remodel Diagram.jpeg

DWV Diagram.jpeg
 

Jeff H Young

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Ok I think it looks good. Some of your wording very confusing I think thats why no one commented but I dont see a problem or know what your asking . just not clear to me ? the vents must not conect less than 6 inches above the flood level of the fixture served . there is no 36 inch rule that I know of perhaps you mean 6 inches above a 30 " tall counter w sink. tub vent is fine.
 

ARC

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Jeff: Thanks for replying and checking. Glad to hear it looks good. Sorry if my question wasn't clear. It's a bit tricky on how to ask. I thought I understood the code correctly but wanted to confirm. I pose the thought process again for any future reader, but no need to reply. Thanks again Jeff.

If fixtures are tied in together for draining before the main stack, does it matter if some fixtures have horizontal runs that are less than 6" for other fixtures who have their own dry vents??? (e.g. Tub vents horizontally into CI stack at 36" and the new 35" heigh vanity has it's own dry vent, but both have their draining tied in together). The drains being tied in together before the main stack was my concern.

My old vanity was at a height of 35". So the horizontal dry vent that went into the CI stack was no longer code since that is/was at 36". My understanding is that is why they also now have the 42" rule for these modern vanities. Since I'm moving the new vanity to the other side of the room I am dry venting it completely separately, but I want to tie the drain into the old CI stack with the alcove tub. The tub will be using the old CI dry vent at the 36" height. I just wanted to make sure there wasn't a conflict with the drains being tied in together before hitting the stack since there still is a horizontal run of dry vent for the tub at a height of 36". It seems to me that IF there was a backup in the main CI stack it would come out of the tub and toilet way before it reaches the 36" height. And if there is just a local backup on the new vanity it will be ok since it has it's own dry vent that is vertical. I hope that clarifies things.
 

Reach4

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If fixtures are tied in together for draining before the main stack, does it matter if some fixtures have horizontal runs that are less than 6" for other fixtures who have their own dry vents??? (e.g. Tub vents horizontally into CI stack at 36" and the new 35" heigh vanity has it's own dry vent, but both have their draining tied in together). The drains being tied in together before the main stack was my concern.
I don't think a 6 inch rule comes up in anything horizontal (except for a 3 inch trap arm minimum length [pipe size x 2]). The 6 inches above the flood level of the served fixtures is the minimum for splitting off vent lines.
 

Mr tee

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You show a 2 X 1 1/4 wye for the trap arm on the vanity, that fitting needs to be a sanitary tee. It would be 2 X 1 1/2 X 1 1/2 with an 1 1/2 X 1 1/4 bushing on top. Normally the vent would be run in 1 1/2 unless the reduced size was to overcome some special problem.
 

Jeff H Young

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Ok good questions first off the rule on reventing is not 42 inches but 6 inches above the flood level of the fixture "Served" in addition an existing vent (toilet) must not have a vent tied into it less than 6 inches above its floof level . So my point is the vent serving the utility sink and tub could tie into the vent stack as low as 6 inches above the over flow of either the tub or toilet whichever is higher. 42 inches is an arbitrary number not in any code I saw but generaly 36 inches is the max overflow on almost any house so add 6 and thats where the 42 inch comes from
Just because the drain from the vanity is connected to the tub means nothing ALL drains are connected just plug up your main and fill with water they all fill up with water .
Valid questions only beef is to make sure the vanity vent is high enough. Hope Im explaining clearly as well, difficult to articulate at times. Good Luck!
 
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