Updated 2026-09-07

Building Code Glossary

Branch: Building Code Definition

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

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Last updated September 7, 2026 · 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.

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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, 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 — 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	Any part of the piping system other than a riser, main or stack.
IPC 2009	Definitions	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	IRC 2009	109
Vents	IPC 2009	99
Vents	IRC 2009	40
Power and Lighting Distribution	IRC 2009	26
Sanitary Drainage	IPC 2009	25
Definitions	IRC 2009	24
Swimming Pools	IRC 2009	23
Services	IRC 2009	19
Definitions	IPC 2009	17
Sanitary Drainage	IRC 2009	17
Electrical Definitions	IRC 2009	13
Fuel Gas	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

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

— IPC 2009 §903.2

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

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 — IRC 2009: All fuel piping, valves and fittings from the outlet of the point ofdeliveryto the outlets of the appliance shutoff valves.
Piping — IRC 2009: Where used in this code, “piping” refers to either pipe or tubing, or both.
System — IFC 2009: An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping.
Stack — IRC 2009: Any main vertical DWV line, including offsets, that extends one or more stories as directly as possible to its vent terminal.
Riser — 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 and the ICC 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.

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 publishes the current model text and the ICC adoption maps show which edition a jurisdiction has adopted; those sources control.

Source links

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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