Residential Gas Piping Rules

By Annie Sisk - Updated March 26, 2018

Many U.S. cities and towns (if not most) have adopted the provisions of the International Code Council’s International Residential Code. That includes the provisions of Chapter 24, which set out requirements for the installation and operation of gas piping systems to residential buildings. Real estate developers and contractors should become familiar with the requirements of chapter 24 before working on gas piping systems in residential structures.


Before installing gas piping systems to residential structures, be sure to check your local code enforcement ordinances. Most U.S. municipalities have adopted the provisions of the International Residential Code, Chapter 24.

Applicability of IRC Chapter 24

Section 2401.1 (101.2) governs the applicability of the provisions of Chapter 24. Specifically, the rule states that the chapter covers fuel gas piping systems, fuel-gas appliances and related accessories, venting systems and combustion air configurations that are most commonly found in single-family and duplex-type dwelling structures. Section G2403 (202) further clarifies what the code means by "fuel gas": “A natural gas, manufactured gas, liquefied petroleum gas or mixtures of these gases.” The chapter's rules apply to the piping system from the point of delivery to the outlet of the appliance shutoff valves.

Chapter 24 provisions of the IRC exempt from these requirements include several types of gas installations, including:

  • LNG (liquefied natural gas) installations
  • Temporary LP gas piping for buildings under construction
  • Portable LP gas appliances that aren’t connected to any fixed piping system

Pipe Sizing Requirements

The size of pipes that must be used in residential piping installations for fuel gas are mandated in Section G2413 (402).

Generally, all systems must be sized and installed so as to keep a sufficient flow of gas to meet the maximum demand for each appliance inlet. The code also provides the method for determining maximum gas demand, the sum of the maximum input of all the appliances served by the piping. For installations in structures located 2,000 feet or more above sea level, the volumetric flow rate of the gas must be adjusted to compensate for altitude effects.

This section also contains technical sizing tables and equations based on the type of pipe (i.e., metallic, semi-rigid copper tubing, corrugated stainless steel tubing or polyethylene plastic pipe) and the type of gas being piped (i.e., natural gas or undiluted propane).

Typically, the appliance manufacturers will provide specifications for pipe size that are often dependent on British Thermal Unit input. This rating commonly applies to furnaces or boilers; most appliances will include plates attached to the unit on which their specific BTU input requirements are inscribed.

Piping Materials

Chapter 24 prohibits the reconditioning or reuse of any pipe, fittings or valves, unless they’re free of debris and are suited to the intended purpose. Any material not explicitly listed in the standards specifications must be specifically tested for the purpose intended, to make sure that the material is safe and will function as intended. It must also be recommended for that use by the manufacturer (so no after-market repurposing is allowed). Additionally, the code inspector assigned to the project must approve the use.

The IRC's Chapter 24 provisions also mandate that steel and wrought iron pipe meet the criteria established by either the American Society of Mechanical Engineers or the American Society for Testing and Materials. Plastic pipe, tubes and fittings must conform to the ASTM standards. The regulation also mandates that steel and wrought iron pipe be marked with labels reading "Gas" and "ASTM D 2513." The code prohibits the use of cast iron pipes in residential gas piping installations.

Installation of New Gas Piping Systems

The chapter also provides rules about where and how residential gas piping can be installed.

Section G2415.3 (404.3) prohibits installing pipes through ductwork, clothing chutes, chimneys, elevator shafts and dumbwaiters. Additionally, any piping installed downstream of the structure’s point of delivery cannot extend through any other townhouse unit besides the one being served by the piping.

Section G2415.5 (404.5) provides that concealed connections or fittings must be limited solely to threaded elbows, tees and couplings, as well as brazed or welding fittings.

Additional key provisions include:

  • A prohibition against gas piping that penetrates any of the structure’s foundation walls at any point that’s below grade; and
  • A requirement that installers must use gas shut-off valves comprised of materials compatible with the piping.

Inspection and Testing of Gas Pipe

Section G2417 sets forth requirements for inspection, testing, and purging of pipe installations.

All piping installations must be both visually inspected as well as pressure tested before acceptance and rendered operational. The inspection and test are aimed at verifying compliance with the requirements of the IRC’s provisions.

The code also provides guidelines and minimum requirements for the testing procedures to be followed under this section.

Other Applicable Laws

The requirements of IRC's Chapter 24 do not apply in a municipality, county or parish that has not adopted its provisions. These local governments may well have enacted other ordinances or regulatory codes, however. That's why it's important to check with your local code enforcement and review the applicable requirements for your project before beginning a residential gas piping project.

Installers should also follow the recommendations of appliance manufacturers in installing gas piping or connecting to piping installations. Finally, most local building codes mandate that a licensed contractor must install gas piping, as these kinds of projects are not suitable for inexperienced or amateur builders.

About the Author

Annie Sisk is a freelance writer who lives in upstate New York. She holds a B.A. in Speech from Catawba College and a J.D. from USC. She has written extensively for publications and websites in the business, management and legal fields.

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