I've always wondered why drain, waste, vent (DWV) requirements have horizontal angle requirements, but not vertical. What is to prevent me from using a series of 45 degree elbows and exceed 135 degrees vertically?

Here is a recent example that got me thinking: I needed to combine 90s in order to avoid a bump out in a corner wall (a single long sweep 90 was too wide to make the framing corner, so I combined one 90 flat against the framing going down towards the floor, and the other facing perpendicular to the wall to reach the main stack). It seems to me that a single horizontal long sweep 90 should be considered different from the situation described. But as I understand it, the vertical aspect is irrelevant and thus they are considered equal from a cleanout perspective because both are only 90 degrees horizontally.

I'm using a locally-modified 2021 UPC, in case that is useful to know.

1 Answer 1


The UPC has a workmanship section, 309, that an inspector can use if something seems "by the book," but doesn't look right. 309.1 reads:

Design, construction, and workmanship shall be in accordance with accepted engineering practices and shall be of such character as to secure the results sought to be obtained by this code.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.