Building Code Glossary
Wet Vent: Building Code Definition
How the IRC 2009 define wet 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
Wet vent is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “A vent that also receives the discharge of wastes from other fixtures.” No other I-Code in this corpus defines it, so the IRC 2009 definition is the one to work from. The term is used in 6 chapters of this corpus, most often in Vents (IPC 2009), Vents (IRC 2009), Definitions (IRC 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?
Wet Vent — IRC 2009, Definitions:
A vent that also receives the discharge of wastes from other fixtures.
What must be verified before using this guidance?
Wet Vent is defined once in this corpus, in the Definitions chapter of the International Residential Code (IRC) 2009:
A vent that also receives the discharge of wastes from other fixtures.
Where wet vent is used in the code
The term appears in 6 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 | 24 |
| Vents | IRC 2009 | 23 |
| Definitions | IRC 2009 | 2 |
| Sanitary Drainage | IRC 2009 | 2 |
| Definitions | IPC 2009 | 1 |
| Sanitary Drainage | IPC 2009 | 1 |
The term in use
How the code actually writes about wet vent, quoted from the 2009 text hosted here:
The wet vent shall be considered the vent for the fixtures and shall extend from the connection of the dry vent along the direction of the flow in the drain pipe to the most downstream fixture drain connection to the horizontal branch drain.
Where the dry vent connects to a water closet fixture drain, the drain shall connect horizontally to the horizontal wet vent system.
Wet 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 IRC | 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 (IRC 2009) | |
| Re-check the requirement that uses it | Sanitary Drainage (IRC 2009) | |
| 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
- Building: Building Code Definition
- Construction Documents: Building Code Definition
- Registered Design Professional: Building Code Definition
- Dwelling Unit: 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 wet vent?
The International Residential Code (IRC) 2009 defines it in Definitions as: “A vent that also receives the discharge of wastes from other fixtures.” 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 wet vent?
In this corpus the term is used across 6 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 is the difference between a wet vent and a yoke vent in plumbing?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “A vent that also receives the discharge of wastes from other fixtures.” It is defined in IRC 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 a wet vent and what is its purpose?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “A vent that also receives the discharge of wastes from other fixtures.” It is defined in IRC 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.
Related pages
- Weatherproof: Building Code Definition
Weatherproof — IRC 2009 definition: Constructed or protected so that exposure to the weather will not interfere with successful operation.
- Web: Building Code Definition
Web — IBC 2009 definition: An interior solid portion of a hollow masonry unit as placed in masonry.
- Wet-chemical Extinguishing System: Building Code Definition
Wet-chemical Extinguishing System — IBC 2009 definition: A solution of water and potassium-carbonate-based chemical, potassium-acetate-based chemical or a combination there…
- Wharf: Building Code Definition
Wharf — IFC 2009 definition: A structure or bulkhead constructed of wood, stone, concrete or similar material built at the shore …
- Wheelchair Space: Building Code Definition
Wheelchair Space — IBC 2009 definition: A space for a single wheelchair and its occupant.
- Whirlpool Bathtub: Building Code Definition
Whirlpool Bathtub — IPC 2009 definition: A plumbing appliance consisting of a bathtub fixture that is equipped and fitted with a circulating …