# Branch: Building Code Definition

> How the IRC 2009, IPC 2009 define branch, where the wording differs, and which chapters depend on the term.

- Canonical: https://harth.build/resources/glossary/branch/
- Last updated: 2026-09-07
- Data source: Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control.

## Key facts

| Fact | Value |
| --- | --- |
| Defined in | IRC 2009, IPC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IRC 2009 Definitions (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 36 (counted across the codes hosted here) |
| Wording identical across codes | No (compare before citing one code's wording under another) |

## Direct answer

Branch is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “Any part of the piping system other than a riser, main or stack.” The IPC 2009 words it differently, in Definitions: “Any part of the piping system except a riser, main or stack.” The IPC 2009 defines the same term with different wording, so the controlling text depends on which code governs the question in front of you — the comparison below sets the versions side by side. The term is used in 36 chapters of this corpus, most often in Branch Circuit and Feeder Requirements (IRC 2009), Vents (IPC 2009), Vents (IRC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted.

*Content and cited inputs reviewed by [Scott Barrington](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.*

## What does this term mean?

**Branch** — IRC 2009, Definitions:

> Any part of the piping system other than a riser, main or stack.

![Labeled code-term definition diagram: Branch: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/branch/diagram-1344.webp)

*How the IRC 2009, IPC 2009 define branch, where the wording differs, and which chapters depend on the term.*

## What must be verified before using this guidance?

Two of the I-Codes in this corpus define **Branch**, and the wording is not identical — read the version that governs your question.

| Code | Where it is defined | Definition |
| --- | --- | --- |
| IRC 2009 | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) | Any part of the piping system other than a riser, main or stack. |
| IPC 2009 | [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) | Any part of the piping system except a riser, main or stack. |

## Where branch is used in the code

The term appears in 36 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

| Chapter | Code | Mentions |
| --- | --- | --- |
| [Branch Circuit and Feeder Requirements](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/branch-circuit-and-feeder-requirements.md) | IRC 2009 | 109 |
| [Vents](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/vents.md) | IPC 2009 | 99 |
| [Vents](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/vents.md) | IRC 2009 | 40 |
| [Power and Lighting Distribution](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/power-and-lighting-distribution.md) | IRC 2009 | 26 |
| [Sanitary Drainage](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/sanitary-drainage.md) | IPC 2009 | 25 |
| [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) | IRC 2009 | 24 |
| [Swimming Pools](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/swimming-pools.md) | IRC 2009 | 23 |
| [Services](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/services.md) | IRC 2009 | 19 |
| [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) | IPC 2009 | 17 |
| [Sanitary Drainage](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/sanitary-drainage.md) | IRC 2009 | 17 |
| [Electrical Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/electrical-definitions.md) | IRC 2009 | 13 |
| [Fuel Gas](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/fuel-gas.md) | IRC 2009 | 12 |

_24 further chapters mention the term._

### The term in use

How the code actually writes about branch, quoted from the 2009 text hosted here:

> This chapter covers branch circuits and feeders and specifies the minimum required branch circuits, the allowable loads and the required overcurrent protection for branch circuits and feeders that serve less than 100 percent of the total dwelling unit load.

— [IRC 2009 §E3701.1](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/branch-circuit-and-feeder-requirements.md)

> A vent stack shall be required for every drainage stack that has five branch intervals or more.

— [IPC 2009 §903.2](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/vents.md)

> This chapter shall control the minimum diameter of vent pipes, circuit vents, branch vents and individual vents, and the size and length of vents and various aspects of vent stacks and stack vents.

— [IRC 2009 §P3101.1](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/vents.md)


## The terms branch is built out of

The definition above leans on 5 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what branch covers:

- **[Piping System](https://harth.build/resources/glossary/piping-system.md)** — IRC 2009: All fuel piping, valves and fittings from the outlet of the point ofdeliveryto the outlets of the appliance shutoff valves.
- **[Piping](https://harth.build/resources/glossary/piping.md)** — IRC 2009: Where used in this code, “piping” refers to either pipe or tubing, or both.
- **[System](https://harth.build/resources/glossary/system.md)** — IFC 2009: An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping.
- **[Stack](https://harth.build/resources/glossary/stack.md)** — IRC 2009: Any main vertical DWV line, including offsets, that extends one or more stories as directly as possible to its vent terminal.
- **[Riser](https://harth.build/resources/glossary/riser.md)** — IRC 2009: A water pipe that extends vertically one full story or more to convey water to branches or to a group of fixtures.

## Branch: what to open, and in what order

Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) cover the middle rows.

| Check | Where | Confirmed |
| --- | --- | --- |
| Read the definition in the adopted IRC | Definitions | |
| Read the definition in the adopted IPC | Definitions | |
| Re-check the requirement that uses it | Branch Circuit and Feeder Requirements (IRC 2009) | |
| Re-check the requirement that uses it | Vents (IPC 2009) | |
| Re-check the requirement that uses it | Vents (IRC 2009) | |
| Re-check the requirement that uses it | Power and Lighting Distribution (IRC 2009) | |
| Confirm the dependent definition | Piping System | |
| Confirm the dependent definition | Piping | |
| Confirm the dependent definition | System | |
| Local amendment to any of the above | Jurisdiction's amendment list | |

**A research aid, not a code determination.** The authority having jurisdiction decides which edition and which amendments apply.

## Where can you explore related guidance?

- [Explore all glossary guidance](https://harth.build/resources/glossary.md)
- [Piping System: Building Code Definition](https://harth.build/resources/glossary/piping-system.md)
- [System: Building Code Definition](https://harth.build/resources/glossary/system.md)
- [Piping: Building Code Definition](https://harth.build/resources/glossary/piping.md)
- [Stack: Building Code Definition](https://harth.build/resources/glossary/stack.md)

## Sources and method

Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control.

### Source links

- [codes.iccsafe.org](https://codes.iccsafe.org/codes)

- [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/)

## Frequently asked questions

### What is the code definition of branch?

The International Residential Code (IRC) 2009 defines it in Definitions as: “Any part of the piping system other than a riser, main or stack.” The 2009 model text is reproduced here; the definition that binds your project is the one in the edition your jurisdiction has adopted, as amended locally.

### Which parts of the code depend on branch?

In this corpus the term is used across 36 chapters, led by Branch Circuit and Feeder Requirements in the IRC 2009. Those are the sections whose scope moves if the definition is amended locally, so read them together with Chapter 2 rather than on their own.

### What is the definition of a branch code?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “Any part of the piping system other than a riser, main or stack.” It is defined in IRC 2009, IPC 2009. Because it is a defined term, whatever the adopted edition says it means is what every section using it means — so check Chapter 2 of that edition and any local amendment before relying on this wording.

### What does IRC mean in building code?

Building is a separate defined term. The IBC 2009 defines it as: “Any structure used or intended for supporting or sheltering any use or occupancy.” That is not the same as branch, which the IRC 2009 defines as “Any part of the piping system other than a riser, main or stack.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

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