IRC Code Finder: Plumbing
Photo: Merle Henkenius
Water and natural gas are unforgiving of shortcuts or mistakes—and so are the plumbing codes. To avoid leaks, floods, and explosions, consult these links before your start running pipe.

Basic Codes

Plumbing Administration Covers the protocols for testing and inspecting new and existing water- and gas-supply lines.

General Plumbing Requirements Specifies how and where pipes are to be installed, inside and outside the house. Section P2605 includes a useful table on the spacing of supports for each kind of pipe material.

Plumbing Fixtures Takes a comprehensive look at the requirements for installing sinks, showers, toilets, bathtubs and every other water-supplied appliance found in a kitchen or bathroom.

Water Heaters Lays out all the rules for locating and connecting one of these devices to a household plumbing system.

Water Supply and Distribution

Protection of Potable Water Supply Explains what it takes to prevent drinking water from being contaminated with liquids, gases, or solids. Includes systems such as lawn irrigation, fire sprinklers, and solar hot water. Useful tables on backflow preventers and air gaps.

Water-Supply System Discusses flow rates, sizing, and pressure limitations for pipes and manifolds. Also addresses water hammer, hose bibs, and valves. Table converts fixture load to gallons-per-minute flow rates.

Materials, Joints and Connections Lists all the materials used for piping in potable water and how to connect them properly.

Sanitary Drainage Encompasses everything concerning the safe conveyance of wastewater out of the house, including drain sizes, materials, and slopes; which bends and sweeps are permissible and where; and the location and spacing of cleanouts. Tables show how determine drain size based on number of fixtures.

Vents Covers all the allowable venting strategies for efficient, no-odor drainage—wet vents, common vents, dry vents circuit vents—as well as the pipe sizes required. Provides diagrams of 12 common venting scenarios diagrams.

Traps Works with the venting system to prevent the sewer gases from entering the home. This section gives minimum trap sizes for plumbing fixtures and appliances, and clarifies what’s allowed and prohibited in trap design.

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