wwhitney
In the Trades
Edit: forgot to hit post, so this response is untimely. Will followup shortly.I am just outside Denver CO. I believe I am under 2021 IPC
Yes, CO uses the IPC per up.codes. Also, CO has adopted the plumbing portion of the IRC, so assuming this is a single family home, your horizontal wet vent would be subject to IRC P3108.1 which requires that any wyes between a fixture drain and the wet vent venting that fixture be horizontal.
Chapter 31 Vents: Vents, Colorado Residential Code 2021 | UpCodes
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But with the IPC, you do have the option to simplify your lav drain routing, by connecting it directly to the WC drain (with a horizontal wye, not from above), and then connecting the shower drain downstream of that. That assumes that your shower trap arm would be under 8' in length.
Cheers, Wayne