Building Code Glossary
Draft: Building Code Definition
How the IRC 2009, IMC 2009 define draft, 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
Draft is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “The pressure difference existing between the appliance or any component part and the atmosphere, that causes a continuous flow of air and products of combustion through the gas passages of the appliance to the atmosphere.” The IMC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 34 chapters of this corpus, most often in Fuel Gas (IRC 2009), Fire and Smoke Protection Features (IBC 2009), Chimneys and 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?
Draft — IRC 2009, Definitions:
The pressure difference existing between the appliance or any component part and the atmosphere, that causes a continuous flow of air and products of combustion through the gas passages of the appliance to the atmosphere.
What must be verified before using this guidance?
Two of the I-Codes in this corpus define Draft, in identical words.
| Code | Where it is defined | Definition |
|---|---|---|
| IRC 2009 | Definitions | The pressure difference existing between the appliance or any component part and the atmosphere, that causes a continuous flow of air and products of combustion through the gas passages of the appliance to the atmosphere. |
| IMC 2009 | Definitions | The pressure difference existing between the appliance or any component part and the atmosphere, that causes a continuous flow of air and products of combustion through the gas passages of the appliance to the atmosphere. |
Where draft is used in the code
The term appears in 34 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 | 333 |
| Fire and Smoke Protection Features | IBC 2009 | 90 |
| Chimneys and Vents | IRC 2009 | 39 |
| Chimneys and Vents | IMC 2009 | 33 |
| Definitions | IRC 2009 | 30 |
| Fire Protection Systems | IFC 2009 | 22 |
| Fire Protection Systems | IBC 2009 | 21 |
| Definitions | IMC 2009 | 17 |
| Building Planning | IRC 2009 | 13 |
| Exhaust Systems | IRC 2009 | 8 |
| Exhaust Systems | IMC 2009 | 6 |
| Fire-resistance-rated Construction | IFC 2009 | 5 |
22 further chapters mention the term.
The term in use
How the code actually writes about draft, quoted from the 2009 text hosted here:
Direct-vent appliances, gas appliances of other than natural draft design and vented gas appliances other than Category I shall be provided with combustion, ventilation and dilution air in accordance with the appliance manufacturer's instructions.
Where required elsewhere in the code, doors in smoke partitions shall meet the requirements for a smoke and draft control door assembly tested in accordance with UL 1784.
A venting system shall satisfy the draft requirements of the appliance in accordance with the manufacturer's installation instructions, and shall be constructed and installed to develop a positive flow to convey combustion products to the outside atmosphere.
The terms draft 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 draft covers:
- Combustion — IRC 2009: In the context of this code, refers to the rapid oxidation of fuel accompanied by the production of heat or heat and light.
- 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.
- Existing — IFC 2009: Buildings, facilities or conditions that are already in existence, constructed or officially authorized prior to the adoption of this code.
Draft: 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 IMC | Definitions | |
| Re-check the requirement that uses it | Fuel Gas (IRC 2009) | |
| Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 2009) | |
| Re-check the requirement that uses it | Chimneys and Vents (IRC 2009) | |
| Re-check the requirement that uses it | Chimneys and Vents (IMC 2009) | |
| Confirm the dependent definition | Combustion | |
| Confirm the dependent definition | Appliance | |
| Confirm the dependent definition | Existing | |
| 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
- Combustion: Building Code Definition
- Appliance: Building Code Definition
- Existing: 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 draft?
The International Residential Code (IRC) 2009 defines it in Definitions as: “The pressure difference existing between the appliance or any component part and the atmosphere, that causes a continuous flow of air and products of combustion through the gas passages of the appliance to the atmosphere.” 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 draft?
In this corpus the term is used across 34 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 the definition of a 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 draft, which the IRC 2009 defines as “The pressure difference existing between the appliance or any component part and the atmosphere, that causes a continuous flow of air and products of combustion through the gas passages of the appliance to the atmosphere.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
What does draft mean?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “The pressure difference existing between the appliance or any component part and the atmosphere, that causes a continuous flow of air and products of combustion through the gas passages of the appliance to the atmosphere.” It is defined in IRC 2009, IMC 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
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