Building Code Glossary
Flue Collar: Building Code Definition
How the IRC 2009 define flue collar, 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
Flue collar is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “The portion of a fuel-burning appliance designed for the attachment of a draft hood, vent connector or venting system.” 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 5 chapters of this corpus, most often in Fuel Gas (IRC 2009), Chimneys and 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?
Flue Collar — IRC 2009, Definitions:
The portion of a fuel-burning appliance designed for the attachment of a draft hood, vent connector or venting system.
What must be verified before using this guidance?
Flue Collar is defined once in this corpus, in the Definitions chapter of the International Residential Code (IRC) 2009:
The portion of a fuel-burning appliance designed for the attachment of a draft hood, vent connector or venting system.
Where flue collar is used in the code
The term appears in 5 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Fuel Gas | IRC 2009 | 58 |
| Chimneys and Vents | IRC 2009 | 6 |
| Definitions | IRC 2009 | 5 |
| Chimneys and Vents | IMC 2009 | 3 |
| Definitions | IMC 2009 | 2 |
The term in use
How the code actually writes about flue collar, quoted from the 2009 text hosted here:
Chimneys shall extend at least 5 feet (1524 mm) above the highest connected appliance drafthood outlet or flue collar: Decorative shrouds shall not be installed at the termination of factory-built chimneys except where such shrouds are listed and labeled for use with the specific factory-built chimney system and are installed in accordance with the manufacturer's installation instructions.
A connector shall not be smaller than the flue collar of the appliance.
The cross-sectional area of a flue serving a solid-fuel-burning appliance shall be not greater than three times the cross-sectional area of the appliance flue collar or flue outlet.
The terms flue collar 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 flue collar covers:
- Venting System — IRC 2009: A continuous open passageway from the flue collar or draft hood of an appliance to the outside atmosphere for the purpose of removing flue or vent gases.
- Vent Connector — IRC 2009: That portion of a venting system which connects the flue collar or draft hood ofan appliance to a vent.
- Draft Hood — IRC 2009: A nonadjustable device built into an appliance, or made as part of the vent connector from an appliance, that is designed to (1) provide for ready escape of the flue gases from the appliance in the event of no draft …
- Appliance — IRC 2009: Utilization equipment, normally built in standardized sizes or types, that is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, food mixing, deep frying, etc.
- Connector — IBC 2009: A mechanical device for securing two or more pieces, parts or members together, including anchors, wall ties and fasteners.
Flue Collar: 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 | Fuel Gas (IRC 2009) | |
| Re-check the requirement that uses it | Chimneys and Vents (IRC 2009) | |
| Re-check the requirement that uses it | Definitions (IRC 2009) | |
| Re-check the requirement that uses it | Chimneys and Vents (IMC 2009) | |
| Confirm the dependent definition | Venting System | |
| Confirm the dependent definition | Vent Connector | |
| Confirm the dependent definition | Draft Hood | |
| 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
- Venting System: Building Code Definition
- Vent Connector: Building Code Definition
- Draft Hood: Building Code Definition
- Connector: 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 flue collar?
The International Residential Code (IRC) 2009 defines it in Definitions as: “The portion of a fuel-burning appliance designed for the attachment of a draft hood, vent connector or venting system.” 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 flue collar?
In this corpus the term is used across 5 chapters, led by Fuel Gas 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 a flue collar?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “The portion of a fuel-burning appliance designed for the attachment of a draft hood, vent connector or venting system.” 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.
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