Michigan Residential Gas Line Code: Permits, Piping, and Inspection

The Michigan residential gas line code is Chapter 24 of the 2015 Michigan Residential Code, which has governed fuel gas piping in one- and two-family homes and townhouses since February 2016 and sets the rules for materials, sizing, burial depth, valves, and pressure testing.¹² The Michigan Department of Licensing and Regulatory Affairs (LARA) and its Bureau of Construction Codes oversee the rules at the state level, and your local building department handles permits and inspections.³

Get a Mechanical Permit Before You Start

Any gas piping work beyond swapping minor parts requires a mechanical permit, pulled before the work begins. A licensed mechanical contractor can pull one for any residential project. If you own and live in (or plan to live in) a single-family home, you can do the work yourself without a contractor’s license, but the permit is still required.⁴

The state application asks for the number of gas piping openings and whether a pressure test is required. State per-item fees include $5 per gas piping opening on a new installation and $20 for a standalone gas pressure test.⁵ Many local jurisdictions add their own base permit and inspection charges, so your total cost depends on where you live and how big the project is.

Call MISS DIG 811 Before Any Digging

If your project involves underground gas piping, Michigan law requires a dig notice to MISS DIG 811. Public Act 174 of 2013 requires the notice at least three business days, and no more than 14 calendar days, before you start excavating.⁶ That applies whether you’re running a new line to a detached garage or just trenching for a gas fire pit.

Utility locators then come out and mark existing underground lines with paint or flags. Digging without calling, or striking a line that was properly marked, can leave you on the hook for fines, repair costs, and injuries. The notice is free; file at MISSDIG811.org or dial 811.⁷

Approved Piping Materials

Chapter 24 is strict about which pipe, tubing, and fittings you can use. The wrong material or an uncertified product means a failed inspection and rework at your cost.

Black Steel Pipe

Black steel is the standard for interior residential gas piping. It handles heat well and lasts. To be compliant it must meet ASTM A53 or A106.⁸ Fittings must be malleable iron or steel, joints must be clean before threading, and the sealant must be rated for fuel gas.

Corrugated Stainless Steel Tubing (CSST)

CSST is common for retrofits because it bends around obstacles without threading. All CSST installed in Michigan must carry the ANSI LC 1/CSA 6.26 certification; uncertified tubing fails inspection.⁸

CSST also needs electrical bonding. Unless the product is specifically listed with an arc-resistant jacket, the entire CSST piping system must be electrically continuous and bonded to the home’s electrical service grounding electrode system, or lightning protection system where one exists. The bonding jumper must be at least 6 AWG copper wire, and the length between the gas piping connection and the grounding electrode cannot exceed 75 feet.⁹ Skipping the bond is a frequent inspection failure and leaves the tubing vulnerable to lightning and surge damage.

Copper Tubing

Copper is allowed only where the gas supplied has a hydrogen sulfide content below 0.3 grains per 100 cubic feet, because higher concentrations corrode the tubing from the inside.⁸ Check with your gas utility if you’re not sure about local gas composition.

Fittings and Sealants

Fittings must be compatible with the pipe material. Cast-iron bushings are prohibited.⁸ Thread sealants must be rated for fuel gas and resist the chemical action of liquefied petroleum gases. Water-line tape or sealant on a gas connection is a violation.

Sizing the Pipe

Pipe size is not cosmetic. Undersized piping starves appliances and causes incomplete combustion. The code requires the system to deliver enough gas, at the minimum inlet pressure each appliance needs, with every appliance running at full capacity at the same time.¹⁰

Correct sizing needs two numbers: the total BTU-per-hour demand of every appliance on the line, and the total length of pipe from the meter to the farthest appliance. Chapter 24 provides more than 20 sizing tables that cross-reference these variables for different pipe materials, pressures, and specific-gravity values.¹⁰ The longest-length method is standard: measure from the meter to the farthest outlet, then size each section by the BTU load it carries over that distance. Adding one appliance to an existing branch? Confirm the existing pipe can handle the extra load before you tap in.

Installation Rules

Burial Depth

Underground gas piping must be buried at least 12 inches below grade.¹¹ Under driveways or other areas with vehicle traffic, the code calls for 18 inches of cover. Underground plastic pipe must be laid with a 14-gauge yellow insulated copper tracer wire alongside it, brought above ground at both ends so the line can be located later with electronic equipment.⁸ Missing tracer wire fails a rough-in inspection every time.

Piping has to enter and leave the building above grade. Underground penetrations through foundation walls below the soil line are not allowed. Where gas piping must run beneath a building, it has to be encased in protective conduit of wrought iron, steel, plastic pipe, or another approved material rated for the loads above.¹²

Where You Cannot Run Gas Pipe

Gas piping cannot run through supply or return air ducts, clothes chutes, chimneys, gas vents, dumbwaiter shafts, or elevator shafts. Concealed piping in solid walls or partitions is prohibited unless it’s in a chase or protective casing.¹² In townhouses, gas piping downstream of the meter cannot pass through any unit other than the one it serves.

Protection and Support

Where gas piping passes through studs or joists and the edge of the hole is less than 1.5 inches from the edge of the wood, a steel shield plate must be installed to stop nails and screws from puncturing the line during later drywall or cabinet work.⁸

All gas piping needs support at intervals that prevent sagging and joint stress. Maximum spacing depends on pipe size and material; smaller steel pipe needs supports as often as every 6 feet, larger horizontal runs up to every 10 feet, and vertical runs at every floor level. Smooth-wall tubing has tighter intervals, and CSST follows the manufacturer’s instructions rather than a fixed table.¹³ Pull the specific spacing for your pipe size from the code table before rough-in.

Shutoff Valves, Connectors, and Sediment Traps

Every appliance needs its own dedicated shutoff valve. It must sit in the same room as the appliance, within 6 feet of it, and upstream of the connector or union.¹⁴ A valve behind a range or dryer counts as accessible because you can slide the appliance out. Burying a shutoff inside a finished wall or ceiling is a concealed location and will not pass.¹⁵

Flexible connectors between an appliance and the rigid piping are limited to 6 feet total, measured along the centerline, and only one connector per appliance is allowed. Rigid metallic piping can run longer if it’s sized as part of the overall system and the shutoff still meets the location rules.

A sediment trap (often called a drip leg) is required at the inlet of every appliance. It’s a tee fitting with a short capped nipple hung vertically at the lowest point before the appliance connection, catching moisture, scale, and debris before they reach the appliance gas valve. Inspectors look for these on every walkthrough, and a missing drip leg is one of the easiest ways to fail.

Pressure Testing and Inspection

Before any fuel gas enters the system, you have to pressure-test it. With all piping assembled and every outlet capped, pressurize with air or an inert gas (never fuel gas) to at least 1.5 times the proposed maximum working pressure, with a floor of 3 psi.¹⁶ A typical residential system runs around 0.5 psi, so you test at the 3 psi minimum.

Leave a calibrated gauge on the system and hold the pressure for at least 10 minutes with no drop at all. Any movement means a leak. Apply a non-corrosive leak-detection solution to each joint, watch for bubbles, and repair. Never check with an open flame.

Once the system holds, call your local building department for inspection. The inspector verifies the gauge is still holding, checks materials against your permit application, confirms tracer wire on underground runs, and looks for shield plates at wood penetrations. If it passes, the system gets tagged for approval, and the gas utility needs to see that tag before turning on supply at the meter.

What Happens if You Skip the Permit

Doing gas work without the required permit carries more than a failed inspection. Under Michigan’s Skilled Trades Regulation Act, a first offense for performing regulated construction work without a license is a misdemeanor with up to a $500 fine, up to 90 days in jail, or both. A second offense doubles to a $1,000 fine and up to one year. A third or subsequent violation is a felony with penalties up to $25,000 and five years of imprisonment.¹⁷

A local building department that finds unpermitted construction can issue a written notice to appear and show cause why the work should not be stopped. If no adequate explanation comes within one business day, a stop-work order gets posted on the property. Ignoring that order can bring a circuit court injunction, and courts can order restitution on top of fines.¹⁷ Unpermitted gas work also creates insurance and resale problems. If a gas-related loss happens in a home with undocumented piping changes, the insurer has grounds to dispute the claim.

1
State of Michigan. Code Books
2
UpCodes. Michigan Residential Code 2021 – Chapter 24 Fuel Gas
3
State of Michigan. Construction Codes
4
State of Michigan. Mechanical Permit Information
5
State of Michigan. Mechanical Permit Application
6
State of Michigan. MIOSHA Fact Sheet – MISS DIG 811 Public Act 174
7
State of Michigan. April Is Safe Digging Month – Contact MISS DIG 811
8
UpCodes. Michigan Residential Code 2015
9
UpCodes. Section G2411 (310) Electrical Bonding
10
UpCodes. Michigan Residential Code 2015 – Chapter 24 Fuel Gas
11
ICC Digital Codes. 2015 Michigan Residential Code – G2415.12 Minimum Burial Depth
12
UpCodes. Section G2415 (404) Piping System Installation
13
UpCodes. Piping Support Intervals
14
ICC Digital Codes. 2018 International Residential Code – G2420.5.1 Located in Same Room
15
UpCodes. Section G2420 (409) Gas Shutoff Valves
16
ICC Digital Codes. 2018 International Residential Code – G2417.4.1 Test Pressure
17
Michigan Legislature. MCL 339-5601