Building Code Glossary
Combustible Liquids: Building Code Definition
How the IMC 2009 define combustible liquids, 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 liquids is a defined term in the International Mechanical Code (IMC) 2009, in Definitions. The code's own words are: “Any liquids having a flash point at or above 100°F (38°C), and that are divided into the following classifications:” No other I-Code in this corpus defines it, so the IMC 2009 definition is the one to work from. The term is used in 24 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 Liquids — IMC 2009, Definitions:
Any liquids having a flash point at or above 100°F (38°C), and that are divided into the following classifications:
What must be verified before using this guidance?
Combustible Liquids is defined once in this corpus, in the Definitions chapter of the International Mechanical Code (IMC) 2009:
Any liquids having a flash point at or above 100°F (38°C), and that are divided into the following classifications:
Where combustible liquids is used in the code
The term appears in 24 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 | 153 |
| Special Detailed Requirements Based on Use and Occupancy | IBC 2009 | 18 |
| Flammable Finishes | IFC 2009 | 17 |
| Scope and Administration | IFC 2009 | 16 |
| Aerosols | IFC 2009 | 15 |
| Motor Fuel-dispensing Facilities and Repair Garages | IFC 2009 | 15 |
| Exhaust Systems | IMC 2009 | 15 |
| Definitions | IFC 2009 | 13 |
| Use and Occupancy Classification | IBC 2009 | 12 |
| Explosives and Fireworks | IFC 2009 | 10 |
| General Requirements | IFC 2009 | 10 |
| Hazardous Materials-general Provisions | IFC 2009 | 10 |
12 further chapters mention the term.
The term in use
How the code actually writes about combustible liquids, quoted from the 2009 text hosted here:
Prevention, control and mitigation of dangerous conditions related to storage, use, dispensing, mixing and handling of flammable and combustible liquids shall be in accordance with Chapter 27 and this chapter.
The storage, use and handling of flammable and combustible liquids shall be in accordance with this section and Chapter 34.
An operational permit is required to conduct a spraying or dipping operation utilizing flammable or combustible liquids or the application of combustible powders regulated by Chapter 15.
The terms combustible liquids is built out of
The definition above leans on 1 other defined term. Each carries its own code definition, and a local amendment to any of them changes what combustible liquids covers:
- 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.
Combustible Liquids: 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 IMC | Definitions | |
| 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 | Scope and Administration (IFC 2009) | |
| Confirm the dependent definition | Flash Point | |
| 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
- Flash Point: Building Code Definition
- Building: Building Code Definition
- Construction Documents: Building Code Definition
- Registered Design Professional: 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 liquids?
The International Mechanical Code (IMC) 2009 defines it in Definitions as: “Any liquids having a flash point at or above 100°F (38°C), and that are divided into the following classifications:” 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 liquids?
In this corpus the term is used across 24 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 are category 1, 2, or 3 flammable liquids?
Flammable Liquids is a separate defined term. The IMC 2009 defines it as: “Any liquid that has a flash point below 100°F (38°C), and has a vapor pressure not exceeding 40 psia (276 kPa) at 100°F (38°C). Flammable liquids shall be known as Class I liquids and shall be divided into the following classifications:” That is not the same as combustible liquids, which the IMC 2009 defines as “Any liquids having a flash point at or above 100°F (38°C), and that are divided into the following classifications:” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
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