# Explosion: Building Code Definition

> How the IBC 2009, IFC 2009 define explosion, where the wording differs, and which chapters depend on the term.

- Canonical: https://harth.build/resources/glossary/explosion/
- Last updated: 2026-09-07
- Data source: 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.

## Key facts

| Fact | Value |
| --- | --- |
| Defined in | IBC 2009, IFC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IBC 2009 Use and Occupancy Classification (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 26 (counted across the codes hosted here) |
| Wording identical across codes | Yes (compare before citing one code's wording under another) |

## Direct answer

Explosion is a defined term in the International Building Code (IBC) 2009, in Use and Occupancy Classification. The code's own words are: “An effect produced by the sudden violent expansion of gases, which may be accompanied by a shock wave or disruption, or both, of enclosing materials or structures. An explosion could result from any of the following:” The IFC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 26 chapters of this corpus, most often in Flammable and Combustible Liquids (IFC 2009), Use and Occupancy Classification (IBC 2009), Explosives and Fireworks (IFC 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](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.*

## What does this term mean?

**Explosion** — IBC 2009, Use and Occupancy Classification:

> An effect produced by the sudden violent expansion of gases, which may be accompanied by a shock wave or disruption, or both, of enclosing materials or structures. An explosion could result from any of the following:

![Labeled code-term definition diagram: Explosion: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/explosion/diagram-1344.webp)

*How the IBC 2009, IFC 2009 define explosion, where the wording differs, and which chapters depend on the term.*

## What must be verified before using this guidance?

Two of the I-Codes in this corpus define **Explosion**, in identical words.

| Code | Where it is defined | Definition |
| --- | --- | --- |
| IBC 2009 | [Use and Occupancy Classification](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/use-and-occupancy-classification.md) | An effect produced by the sudden violent expansion of gases, which may be accompanied by a shock wave or disruption, or both, of enclosing materials or structures. An explosion could result from any of the following: |
| IFC 2009 | [Hazardous Materials-general Provisions](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/hazardous-materials-general-provisions.md) | An effect produced by the sudden violent expansion of gases, which may be accompanied by a shock wave or disruption, or both, of enclosing materials or structures. An explosion could result from any of the following: |

## Where explosion is used in the code

The term appears in 26 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](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-and-combustible-liquids.md) | IFC 2009 | 39 |
| [Use and Occupancy Classification](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/use-and-occupancy-classification.md) | IBC 2009 | 38 |
| [Explosives and Fireworks](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/explosives-and-fireworks.md) | IFC 2009 | 30 |
| [Hazardous Materials-general Provisions](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/hazardous-materials-general-provisions.md) | IFC 2009 | 30 |
| [Exhaust Systems](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/exhaust-systems.md) | IMC 2009 | 25 |
| [Special Detailed Requirements Based on Use and Occupancy](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/special-detailed-requirements-based-on-use-and-occupancy.md) | IBC 2009 | 24 |
| [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-protection-systems.md) | IFC 2009 | 9 |
| [Lumber Yards and Woodworking Facilities](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/lumber-yards-and-woodworking-facilities.md) | IFC 2009 | 9 |
| [Combustible Dust-producing Operations](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/combustible-dust-producing-operations.md) | IFC 2009 | 8 |
| [Flammable Finishes](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-finishes.md) | IFC 2009 | 8 |
| [Organic Peroxides](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/organic-peroxides.md) | IFC 2009 | 7 |
| [Definitions](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/definitions.md) | IFC 2009 | 6 |

_14 further chapters mention the term._

### The term in use

How the code actually writes about explosion, quoted from the 2009 text hosted here:

> In the event of a spill, leak or discharge from a tank system, a site assessment shall be completed by the owner or operator of such tank system if the fire code official determines that a potential fire or explosion hazard exists.

— [IFC 2009 §3403.3](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-and-combustible-liquids.md)

> The quantity-distance (Q-D) tables in Sections 3304.5 and 3305.3 shall be used to provide the minimum separation distances from potential explosion sites as set forth in Tables 3301.8.1 (1) through 3301.8.1 (3).

— [IFC 2009 §3301.8.1](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/explosives-and-fireworks.md)

> Safeguards shall be provided to minimize the risk of and limit damage from a fire or explosion involving explosive hazardous materials whereby such fire or explosion could endanger or lead to the endangerment of people or property.

— [IFC 2009 §2701.3.3.7](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/hazardous-materials-general-provisions.md)

## Explosion: what to open, and in what order

Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-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 | Hazardous Materials-general Provisions | |
| Re-check the requirement that uses it | Flammable and Combustible Liquids (IFC 2009) | |
| Re-check the requirement that uses it | Use and Occupancy Classification (IBC 2009) | |
| Re-check the requirement that uses it | Explosives and Fireworks (IFC 2009) | |
| Re-check the requirement that uses it | Hazardous Materials-general Provisions (IFC 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](https://harth.build/resources/glossary.md)
- [Corrosive: Building Code Definition](https://harth.build/resources/glossary/corrosive.md)
- [Hazardous Materials: Building Code Definition](https://harth.build/resources/glossary/hazardous-materials.md)
- [Combustible Liquid: Building Code Definition](https://harth.build/resources/glossary/combustible-liquid.md)
- [Handling: Building Code Definition](https://harth.build/resources/glossary/handling.md)

## 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](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.

### Source links

- [codes.iccsafe.org](https://codes.iccsafe.org/codes)

- [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/)

## Frequently asked questions

### What is the code definition of explosion?

The International Building Code (IBC) 2009 defines it in Use and Occupancy Classification as: “An effect produced by the sudden violent expansion of gases, which may be accompanied by a shock wave or disruption, or both, of enclosing materials or structures. An explosion could result from any of the following:” 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 explosion?

In this corpus the term is used across 26 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 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 explosion, which the IBC 2009 defines as “An effect produced by the sudden violent expansion of gases, which may be accompanied by a shock wave or disruption, or both, of enclosing materials or structures. An explosion could result from any of the following:” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

### What is the definition of fire area in a building?

Fire Area is a separate defined term. The IBC 2009 defines it as: “The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building. Areas of the building not provided with surrounding walls shall be included in the fire area if such areas are included within the horizontal projection …” That is not the same as explosion, which the IBC 2009 defines as “An effect produced by the sudden violent expansion of gases, which may be accompanied by a shock wave or disruption, or both, of enclosing materials or structures. An explosion could result from any of the following:” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

### What does explosion mean?

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: “An effect produced by the sudden violent expansion of gases, which may be accompanied by a shock wave or disruption, or both, of enclosing materials or structures. An explosion could result from any of the following:” 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.

---

- Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fexplosion%2F
- View this page in a browser: https://harth.build/resources/glossary/explosion/
- All resources for agents: https://harth.build/llms.txt