Building Code Glossary
Combustible Liquid: Building Code Definition
How the IBC 2009, IFC 2009 define combustible liquid, 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
Combustible liquid is a defined term in the International Building Code (IBC) 2009, in Use and Occupancy Classification. The code's own words are: “A liquid having a closed cup flash point at or above 100°F (38°C). Combustible liquids shall be subdivided as follows:” The IFC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 28 chapters of this corpus, most often in Flammable and Combustible Liquids (IFC 2009), Special Detailed Requirements Based on Use and Occupancy (IBC 2009), Flammable Finishes (IFC 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?
Combustible Liquid — IBC 2009, Use and Occupancy Classification:
A liquid having a closed cup flash point at or above 100°F (38°C). Combustible liquids shall be subdivided as follows:
What must be verified before using this guidance?
Two of the I-Codes in this corpus define Combustible Liquid, in identical words.
| Code | Where it is defined | Definition |
|---|---|---|
| IBC 2009 | Use and Occupancy Classification | A liquid having a closed cup flash point at or above 100°F (38°C). Combustible liquids shall be subdivided as follows: |
| IFC 2009 | Flammable and Combustible Liquids | A liquid having a closed cup flash point at or above 100°F (38°C). Combustible liquids shall be subdivided as follows: |
Where combustible liquid is used in the code
The term appears in 28 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Flammable and Combustible Liquids | IFC 2009 | 180 |
| Special Detailed Requirements Based on Use and Occupancy | IBC 2009 | 26 |
| Flammable Finishes | IFC 2009 | 23 |
| Motor Fuel-dispensing Facilities and Repair Garages | IFC 2009 | 22 |
| Scope and Administration | IFC 2009 | 22 |
| Hazardous Materials-general Provisions | IFC 2009 | 21 |
| Use and Occupancy Classification | IBC 2009 | 19 |
| Definitions | IFC 2009 | 18 |
| Aerosols | IFC 2009 | 15 |
| Exhaust Systems | IMC 2009 | 15 |
| Manufacture of Organic Coatings | IFC 2009 | 13 |
| Aviation Facilities | IFC 2009 | 12 |
16 further chapters mention the term.
The term in use
How the code actually writes about combustible liquid, quoted from the 2009 text hosted here:
Tanks which are to be reinstalled for flammable or combustible liquid service shall be in accordance with this chapter, ASME Boiler and Pressure vessel Code (Section VIII), API 12-P, API 1615, UL 58 and UL 1316.
Flammable and combustible liquid fuel-dispensing and containment equipment shall be periodically inspected where required by the fire code officialto verify that it is in proper working order and not subject to leakage.
Empty flammable or combustible liquid containers shall be removed to a detached, outside location and, if not cleaned on the premises, the empty containers shall be removed from the plant as soon as practical.
The terms combustible liquid is built out of
The definition above leans on 4 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what combustible liquid covers:
- Combustible Liquids — IMC 2009: Any liquids having a flash point at or above 100°F (38°C), and that are divided into the following classifications:
- Flash Point — IBC 2009: The minimum temperature in degrees Fahrenheit at which a liquid will give off sufficient vapors to form an ignitable mixture with air near the surface or in the container, but will not sustain combustion.
- Liquid — IBC 2009: A material that has a melting point that is equal to or less than 68°F (20°C) and a boiling point that is greater than 68°F (20°C) at 14.7 pounds per square inch absolute (psia) (101 kPa).
- Shall — IRC 2009: The term, when used in the code, is construed as mandatory.
Combustible Liquid: 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 IBC | Use and Occupancy Classification | |
| Read the definition in the adopted IFC | Flammable and Combustible Liquids | |
| Re-check the requirement that uses it | Flammable and Combustible Liquids (IFC 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 | Flammable Finishes (IFC 2009) | |
| Re-check the requirement that uses it | Motor Fuel-dispensing Facilities and Repair Garages (IFC 2009) | |
| Confirm the dependent definition | Combustible Liquids | |
| Confirm the dependent definition | Flash Point | |
| Confirm the dependent definition | Liquid | |
| 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
- Combustible Liquids: Building Code Definition
- Flash Point: Building Code Definition
- Liquid: 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 combustible liquid?
The International Building Code (IBC) 2009 defines it in Use and Occupancy Classification as: “A liquid having a closed cup flash point at or above 100°F (38°C). Combustible liquids shall be subdivided as follows:” 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 combustible liquid?
In this corpus the term is used across 28 chapters, led by Flammable and Combustible Liquids in the IFC 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 considered a combustible liquid?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Use and Occupancy Classification: “A liquid having a closed cup flash point at or above 100°F (38°C). Combustible liquids shall be subdivided as follows:” It is defined in IBC 2009, IFC 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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