Residential Gas Piping Rules

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 Chapter 24, which sets 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.

​Read More:​ Residential Building Codes

Section 2401.1 (101.2) governs the applicability of the provisions of Chapter 24, which 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.

Several types of gas installations are exempt from these regulations, 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

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 and adjustments that must be made to compensate for higher altitude installations.

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).

Generally, appliance manufacturers will provide specifications for pipe size that are often dependent on British Thermal Unit (BTU) inputs such as furnaces or boilers.

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 project inspector must approve the use.

The IRC's Chapter 24 provisions also mandates standards for steel and wrought iron pipe. 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.

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.

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There are requirements for inspection, testing, and purging of pipe installations. All piping installations must be both visually inspected and pressure tested before being rendered operational.

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 have other ordinances or regulatory codes. 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 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.

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