Can a Flexible Gas Connector Go Through a Wall, Floor, Cabinet, or Furnace Cabinet? (IRC 2018)

Quick Answer

No. IRC 2018 Section G2422.1.2 explicitly prohibits flexible gas appliance connectors from running through walls, floors, ceilings, partitions, or appliance housings such as furnace cabinets. A flexible connector is intended only for the final visible connection from the rigid gas supply stub-out to the appliance inlet — it cannot be used to route gas through any concealed space or structural element.

What G2422.1.2 Actually Requires

IRC 2018 Section G2422.1.2 lists the prohibited locations and configurations for flexible gas appliance connectors. The section explicitly states that connectors shall not be run through walls, floors, ceilings, or enclosed partitions, nor through appliance housings. This means a flexible connector must remain fully visible and in the open space between the supply stub-out and the appliance inlet — it cannot pass through any building component or be enclosed in any way.

Additional prohibitions in G2422.1.2 include: connectors shall not be installed in a concealed location where they are not visible and accessible, connectors shall not be used as a substitute for rigid gas piping in a permanent installation where the appliance is not meant to be moved, and connectors shall not be spliced or connected to other connectors to increase length. The maximum connector length for most appliances under G2422.1 is 3 feet; ranges and dryers are permitted connectors up to 6 feet.

A furnace cabinet is specifically mentioned in G2422.1.2 because a flexible connector entering the furnace cabinet would be concealed within the appliance housing. The gas connection to the furnace must be made at the exterior of the furnace cabinet — typically at a threaded inlet fitting on the cabinet wall — using rigid pipe up to that point. Only the appliance manufacturer's own internal tubing inside the cabinet is acceptable; an installer-supplied flexible connector cannot penetrate the cabinet wall.

The prohibition on floor penetrations is particularly important in kitchen and laundry installations where a gas range or dryer sits on top of a floor, and an installer might be tempted to route the flexible connector down through a hole in the floor to a supply in the crawl space or basement below. This is explicitly prohibited — the supply must be terminated with a rigid stub-out in the same room as the appliance.

IRC 2018 Section G2422.1.2 explicitly prohibits gas appliance connectors from being concealed within or extended through walls, floors, partitions, or ceilings. This prohibition exists because flexible connectors are subject to wear, corrosion, and mechanical damage over time. Conditions that can develop inside a concealed space may not be detected until a leak occurs. A flexible connector that develops a slow leak inside a wall cavity will accumulate gas until it reaches an ignition source or is detected by odor that has migrated through the wall materials. The prohibition ensures that all flexible connector connections remain visible and accessible for inspection. If a gas appliance is located in a position where the supply pipe must pass through a wall, rigid pipe must be used for the through-wall portion, with the flexible connector connection made on the accessible side of the wall where the connection can be visually inspected during every annual gas appliance service visit.

Why This Rule Exists

Flexible gas connectors are designed for vibration isolation and minor movement at the final appliance connection — they are not designed for permanent concealed installation. The corrugated metallic construction that provides flexibility also makes connectors more susceptible to corrosion and fatigue cracking than rigid pipe. In a wall or floor, a leaking connector cannot be seen, smelled, or inspected until gas has accumulated to potentially dangerous concentrations. The prohibition keeps flexible connectors in accessible, visible locations where any leak would be immediately detectable.

What the Inspector Checks at Rough and Final

At rough inspection, the inspector checks that no flexible connector routes are planned through wall or floor openings and that rigid supply stub-outs are correctly located in the same room as the intended appliances. At final inspection, the inspector will verify: all flexible connectors are fully visible between the supply stub-out and the appliance inlet, no connector passes through any wall, floor, ceiling, partition, or appliance housing, connector lengths do not exceed the allowable maximum (3 feet for most appliances, 6 feet for ranges and dryers), connectors are not kinked, bent beyond the minimum bend radius, stretched under tension, or corroded, and each connector is listed for the gas service (natural gas or LP). The inspector may reject a connector that shows significant corrosion or that has been in service for an extended period without replacement.

What Contractors Need to Know

Plan rigid piping runs so that supply stub-outs terminate in the same room as the appliance they serve, at a location accessible without moving the appliance. For a gas range, the stub-out is typically on the wall behind the range at floor level, or through the floor into the cabinet space behind the range — not through the floor under the range. For a furnace, the stub-out is typically within 3 feet of the furnace inlet on the same wall. For a dryer, the stub-out is on the laundry room wall within 6 feet of the dryer position.

Use only connectors listed for the specific gas type in use and rated for the inlet pressure. Replace connectors that are kinked, corroded, or that have been previously used with a different appliance. Flexible connectors are not reusable — when an appliance is replaced, the connector should be replaced as well. Never use a connector to make up for a stub-out that is more than the allowable distance away from the appliance inlet.

When relocating a gas appliance during kitchen renovation, particularly when a range or cooktop is moved from its original location, verify that the new position allows the flexible connector to be installed entirely in the exposed space behind or beside the appliance without concealment. A range relocated 24 inches to the left of the original gas outlet requires the gas supply pipe to be extended 24 inches to the new position using rigid pipe before the flexible connector is attached. This rigid pipe extension must be in the wall if it runs horizontally but must transition to exposed pipe before the flexible connector is attached. The transition fitting at the wall must be in an accessible location. Inside the toe-kick space of a cabinet that has a removable panel is acceptable; permanently sealed behind the cabinet back is not. Document the gas pipe extension on the as-built drawings for the kitchen renovation permit.

What Homeowners Get Wrong

The most dangerous homeowner error is using a flexible connector to run gas from a supply in one room to an appliance in an adjacent room by threading the connector through a wall opening. This is seen in situations where a homeowner wants to add a gas appliance but the supply is in the wrong room or the wrong location. The correct solution is to have a plumber extend the rigid piping into the correct room — not to run a flexible connector through a wall. Another common violation occurs when a range or dryer is replaced — the installer reuses the old connector, which may be kinked, corroded, or rated for a different gas type than what is currently in use.

State and Local Amendments

IRC 2018 states — TX, GA, VA, NC, SC, TN, AL, MS, KY, and MO — follow G2422.1.2 without significant modification. In California (which has its own code), flexible connector requirements are even more stringent, limiting connectors to 18 inches for seismic flexibility reasons. No IRC 2018 states impose a shorter maximum length than the code, but some local utilities recommend replacing connectors over 5 years old as preventive maintenance.

IRC 2021 did not change the prohibited locations in G2422.1.2. The wall, floor, ceiling, and appliance housing prohibitions carried forward unchanged from the 2018 edition.

When to Hire a Licensed Gas Plumber

If a flexible connector violation exists — for example, a connector that runs through a wall from a supply in an adjacent room — the repair requires extending rigid piping through or along the wall to create a proper stub-out in the correct location. This is licensed gas pipe work requiring a permit. Do not attempt to correct a through-wall connector violation by simply adding a longer connector — the only compliant solution is proper rigid piping terminating in the same room as the appliance.

Common Violations Found at Inspection

• Flexible connector routed through a cabinet wall or appliance housing (furnace cabinet) to reach the gas inlet inside
• Connector run down through the floor to a supply in the basement — floor penetration prohibited
• Two connectors spliced together to increase length beyond 6 feet — splicing is prohibited
• Connector routed through a small hole in a partition wall to reach an appliance in the next room
• Connector length exceeding 3 feet (or 6 feet for ranges and dryers) — supply stub-out not placed close enough to the appliance
• Old corroded connector reused when appliance is replaced — should be replaced with every appliance change
• Connector kinked or sharply bent to navigate around an obstacle — creates stress concentration and failure risk
• Connector not listed for the gas type in use — LP-only connector used on a natural gas system