How would you frame this to accommodate plumbing?

I’m framing a 2-story garage that is attached to the main house via a mudroom. The plumber wants to run his waste lines under the stairs through the mudroom floor… I’m framing a 2-story garage that is attached to the main house via a mudroom. The plumber wants to run his waste lines under the stairs through the mudroom floor…Read MoreGreenBuildingAdvisor