Residential Rough in Plumbing Requirements


Residential plumbing brings water into the home for drinking, bathing and utility use by laundry machines, dishwashers and icemakers. The plumbing's most visible parts are fixtures such as faucets, spigots and showerheads. However, before these fixtures are installed, plumbers must install rough-in plumbing that connects to the city’s water supply and sewer system.


  • Local and state building authorities dictate the requirements for both rough-in and finish plumbing for homes and other structures in their jurisdictions. With some variations, all base their regulations on the Uniform Plumbing Code produced by the International Association of Plumbing and Mechanical Officials. The goal of IAPMO is to protect public health and safety by implementing “comprehensive plumbing and mechanical systems around the world.” Though most jurisdictions use the 2009 UPC at the time of publication, many will switch to the 2012 version. Other codes that can affect rough-in requirements include the International Residential Code, the National Electrical Code and the International Fire Code.


  • Only some of the requirements from the UPC are listed in this article. No plumbing pipes can be directly embedded in concrete. However, they can pass through concrete walls and floors if they are protected from breaking, such as with sleeves that are not bored or drilled. Spaces around pipes passing through floors must be sealed. Underground water lines require type L copper. Type M copper is allowed for underground pipes outside the structure. However, copper joints under a slab require brazing. Backwater valves must remain accessible for inspection and repair.


  • Drains, wastes and vents require testing with a 10-foot head for 15 minutes. If they are not made of plastic, they may also be tested with air at 5 pounds per square inch for 15 minutes. Any hangers and straps used for support must allow free movement of the pipe without compression, distortion, cutting or other deformity. Plastic pipes need support every 4 feet, plus support where horizontal branches connect. Vertical lines need support lines at the base and at each floor, with guides at mid-story. Any openings for tub waste that go into crawl spaces must be closed off with metal collars or metal screen connected to the structure. Openings must be less than 1/2 inch in diameter.


  • All faucet and showerhead fittings require rigid support. Showers need a minimum interior finished area of 900 square inches, with a minimum clear area of 30 inches by 30 inches from the floor of the shower to 70 inches above it. They must have a valve that balances water pressure to prevent scalding. Toilets must be set at a minimum 15 inches as measured from its center to the side wall. The toilet ring must be less than 6 feet from a vent.

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