Building Code Glossary
Cubic Foot: Building Code Definition
How the IRC 2009 define cubic foot, 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
Cubic foot is a defined term in the International Residential Code (IRC) 2009, in Fuel Gas. The code's own words are: “The amount of gas that occupies 1 cubic foot (0.02832 m3) when at a temperature of 60°F (16°C), saturated with water vapor and under a pressure equivalent to that of 30 inches of mercury (101 kPa).” 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 29 chapters of this corpus, most often in Fuel Gas (IRC 2009), Special Detailed Requirements Based on Use and Occupancy (IBC 2009), Exhaust Systems (IMC 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?
Cubic Foot — IRC 2009, Fuel Gas:
The amount of gas that occupies 1 cubic foot (0.02832 m3) when at a temperature of 60°F (16°C), saturated with water vapor and under a pressure equivalent to that of 30 inches of mercury (101 kPa).
What must be verified before using this guidance?
Cubic Foot is defined once in this corpus, in the Fuel Gas chapter of the International Residential Code (IRC) 2009:
The amount of gas that occupies 1 cubic foot (0.02832 m3) when at a temperature of 60°F (16°C), saturated with water vapor and under a pressure equivalent to that of 30 inches of mercury (101 kPa).
Where cubic foot is used in the code
The term appears in 29 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 | 9 |
| Special Detailed Requirements Based on Use and Occupancy | IBC 2009 | 8 |
| Exhaust Systems | IMC 2009 | 8 |
| Fire and Smoke Protection Features | IBC 2009 | 7 |
| Flammable and Combustible Liquids | IFC 2009 | 7 |
| Commercial Energy Efficiency | IECC 2009 | 6 |
| Foundations | IRC 2009 | 6 |
| Definitions | IMC 2009 | 5 |
| Duct Systems | IRC 2009 | 5 |
| Building Services and Systems | IFC 2009 | 4 |
| Compressed Gases | IFC 2009 | 4 |
| Specific Appliances, Fireplaces and Solid Fuel-burning Equipment | IMC 2009 | 4 |
17 further chapters mention the term.
The term in use
How the code actually writes about cubic foot, quoted from the 2009 text hosted here:
The aggregate input rating of all unvented appliances installed in a room or space shall not exceed 20 Btu/h per cubic foot(0.21 kW/m3) of volume of such room or space.
The minimum density of foam plastics used in signs shall not be less than 20 pounds per cubic foot (pcf) (320 kg/m3).
"Mass walls" shall include walls weighing at least (1) 35 pounds per square foot (170 kg/m2) of wall surface area or (2) 25 pounds per square foot (120 kg/m2) of wall surface area if the material weight is not more than 120 pounds per cubic foot (1900 kg/m3).
Cubic Foot: 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 | Fuel Gas | |
| Re-check the requirement that uses it | Fuel Gas (IRC 2009) | |
| Re-check the requirement that uses it | Special Detailed Requirements Based on Use and Occupancy (IBC 2009) | |
| Re-check the requirement that uses it | Exhaust Systems (IMC 2009) | |
| Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 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
- Code Official: Building Code Definition
- Code: Building Code Definition
- Fuel Gas: Building Code Definition
- Vent: 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 cubic foot?
The International Residential Code (IRC) 2009 defines it in Fuel Gas as: “The amount of gas that occupies 1 cubic foot (0.02832 m3) when at a temperature of 60°F (16°C), saturated with water vapor and under a pressure equivalent to that of 30 inches of mercury (101 kPa).” 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 cubic foot?
In this corpus the term is used across 29 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 the International Building Code (IBC)?
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 cubic foot, which the IRC 2009 defines as “The amount of gas that occupies 1 cubic foot (0.02832 m3) when at a temperature of 60°F (16°C), saturated with water vapor and under a pressure equivalent to that of 30 inches of mercury (101 kPa).” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
What does cubic foot stand for?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Fuel Gas: “The amount of gas that occupies 1 cubic foot (0.02832 m3) when at a temperature of 60°F (16°C), saturated with water vapor and under a pressure equivalent to that of 30 inches of mercury (101 kPa).” 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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