WI Size of a single Roof Vent

Users who are viewing this thread


Reaction score
Trying to understand the WI plumbing code in connection to the roof vent. We are in the planning stages of a home remodel. The original house plumbing has 4 inch PVC that exits the basement out to the septic. Inside the basement the PVC runs about 25 feet horizontally (at about 7' AFF in the basement) before it turns up and connects to 4" cast iron and then goes up through the roof.

We would like to shorten the horizontal run in the basement to about 16 - 18 feet because of a relocation of the bathroom on the second floor (second and first floor would be closer together after the remodel). We would relocate and replace the cast iron with 4" PVC up till the second floor bathroom (wet part of the pipe), then the vent would exit through a new hole in the roof as a 3" PVC (convert everything to PVC).

Table 382.31−2 Size and Length of Vent Stacks and Stack Vents if I understand correctly says 4" drain, and 3" roof vent would be a max of 180 feet of the "main" stack?
Table 382.31−3 Minimum Diameters And Maximum Length Of Vents. Per the table if you have 3" vent and 24 dfu then there is no limit (NL) in the length. We have planned 22 WFU in the system, which we believe complies with the code?

Thank you
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks