Building Code Glossary
Branch Vent: Building Code Definition
How the IPC 2009 define branch vent, where the wording differs, and which chapters depend on the term.
On this page
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.
Direct answer
Branch vent is a defined term in the International Plumbing Code (IPC) 2009, in Definitions. The code's own words are: “A vent connecting one or more individual vents with a vent stack or stack vent.” No other I-Code in this corpus defines it, so the IPC 2009 definition is the one to work from. The term is used in 3 chapters of this corpus, most often in Vents (IPC 2009), Vents (IRC 2009), Definitions (IPC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted. Record the jurisdiction, the adopted edition, the application date and any local amendment that rewrites the definition before you use it on a live project, because a term redefined by amendment changes every requirement that depends on it.
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 Vent — IPC 2009, Definitions:
A vent connecting one or more individual vents with a vent stack or stack vent.
What must be verified before using this guidance?
Branch Vent is defined once in this corpus, in the Definitions chapter of the International Plumbing Code (IPC) 2009:
A vent connecting one or more individual vents with a vent stack or stack vent.
Where branch vent is used in the code
The term appears in 3 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Vents | IPC 2009 | 12 |
| Vents | IRC 2009 | 10 |
| Definitions | IPC 2009 | 1 |
The term in use
How the code actually writes about branch vent, quoted from the 2009 text hosted here:
All vent and branch vent pipes shall be so graded and connected as to drain back to the drainage pipe by gravity.
Vent and branch vent pipes shall be graded, connected and supported to allow moisture and condensate to drain back to the soil or waste pipe by gravity.
The terms branch vent is built out of
The definition above leans on 3 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what branch vent covers:
- Vent Stack — IRC 2009: A vertical vent pipe installed to provide circulation of air to and from the drainage system and which extends through one or more stories.
- Stack Vent — IRC 2009: The extension of soil or waste stack above the highest horizontal drain connected.
- Stack — IRC 2009: Any main vertical DWV line, including offsets, that extends one or more stories as directly as possible to its vent terminal.
Branch Vent: 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 IPC | Definitions | |
| 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 | Definitions (IPC 2009) | |
| Confirm the dependent definition | Vent Stack | |
| Confirm the dependent definition | Stack Vent | |
| Confirm the dependent definition | Stack | |
| 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
- Vent Stack: Building Code Definition
- Stack Vent: Building Code Definition
- Stack: Building Code Definition
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 vent?
The International Plumbing Code (IPC) 2009 defines it in Definitions as: “A vent connecting one or more individual vents with a vent stack or stack vent.” 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 vent?
In this corpus the term is used across 3 chapters, led by Vents in the IPC 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 are the building code requirements for venting in Florida?
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 vent, which the IPC 2009 defines as “A vent connecting one or more individual vents with a vent stack or stack vent.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
What is a branch vent in plumbing?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IPC 2009 states, in Definitions: “A vent connecting one or more individual vents with a vent stack or stack vent.” It is defined in IPC 2009. It is not the same as Plumbing, which the IRC 2009 defines separately as “For the purpose of this code, plumbing refers to those installations, repairs, maintenance and alterations regulated by Chapters 25 through 33.” 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 is the code for venting a toilet?
Venting is a separate defined term. The IRC 2009 defines it as: “Removal of combustion products to the outdoors.” That is not the same as branch vent, which the IPC 2009 defines as “A vent connecting one or more individual vents with a vent stack or stack vent.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
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