Johnstown, PA · 2026-08-16
Bathroom Addition Rough-In Plumbing Checklist for Johnstown Homes
Short answer: A bathroom addition fails when the drain is undersized, the vent is missing, or the supply is tied into a starved galvanized line. Rough-in before drywall.
GSC already sends “plumber for bathroom addition” and “plumber for rough plumbing” toward this site. Rough plumbing installation is the service page. This is the homeowner checklist.
Drain and vent
Toilet, shower, and lav each need proper slope and a vent that actually sees atmosphere - not a “cheater” that dumps sewer gas into an attic.
Supply
Do not tee a new bath off a 1/2-inch galvanized that already feeds the kitchen. We upsize or add a manifold so the shower does not die when the washer fills.
Inspections
Cambria County and borough inspectors want to see the rough before insulation. We pressure-test the new work. That is the point of our testing specialty.
Need this handled in Cambria County?
Local Plumbers Pro - licensed plumbing, leak detection, and 24/7 emergencies in Johnstown and Ferndale. Call (877) 853-2993.
Call (877) 853-2993Questions we hear on this topic
Yes, including ejector pits when the drain is below the sewer.
Yes. We schedule around framing so we are not cutting finished walls.