Advice on Venting for Bathroom Re-model

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GrnMitsu

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Hi All - I am a DIY and am remodeling my bathroom down to the studs.
I need advice on if I need to change venting.

There will be 31 fixture Units in the house. Venting is 1.5 inch with one 3 inch out the roof.
The bathroom I am remodeling will have 7 fixture units (1 toilet, 1 bathtub, Double Vanity w/ 2 faucets)

Should I add another vent (currently there are only 2) before the p-trap from the bathtub?
Should I increase the vent pipe diameter to 2 inches?
Is One 3 inch vent enough for 31 fixture units in Ohio?

Diagram.jpg

WP_001044.jpg

View attachment Bathroom.pdf

Thank you for your thoughts!
 
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hj

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To answer your last question first. If 3" were not adequate for a vent, then it would definitely be too small for a drain. But, you do NOT have a 3" vent, you have TWO 1 1/2" vents which are the equivalent of a 2" vent, regardless of the size pipe through the roof. Whatever you are using to vent the toilet will probably have to be 2", and you do not need 3" for the two sinks.
 
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GrnMitsu

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Thanks for your response hj. The vent for the toilet is what really concerns me. The toilet vent is 7 inches from the p-trap on the bathtub and 1 foot 5 inches from where the 1.5 inch dia. drain for the tub meets the 3 inch dia. drain for the toilet. The yellow arrow in the first picture below indicates where the T is for the vent. Both the bath and the toilet share this vent and I do not think this is adequate.

ToiletBathVent.jpg

The second picture shows where the 1.5 inch dia. drain (green arrow) and vent for the bathtub meet the 3 inch dia. toilet drain (red arrow).

bathToiletjoin.jpg
 

hj

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vent

Technically, in most areas the tub vent would be too small to use with the toilet and the tee would be an improper fitting to make the connection, BUT, it depends on your code, since some versions are very lenient about it. In most cases, one of the two vents would have to be 2" until it reaches the 3" pipe through the roof.
 

GrnMitsu

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Thanks again hj.

What are your thoughts on adding a 2 inch vent upstream before the p-trap on the bathtub?

It did not seem like enough venting. I found a good resource "Plumbing a house" by Peter Hemp. I posted a picture with a very good table for vents below.

WP_001075.jpg
 
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