# Hazardous Location: Building Code Definition

> How the IRC 2009, IMC 2009 define hazardous location, where the wording differs, and which chapters depend on the term.

- Canonical: https://harth.build/resources/glossary/hazardous-location/
- 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 | IRC 2009, IMC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IRC 2009 Fuel Gas (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 16 (counted across the codes hosted here) |
| Wording identical across codes | Yes (compare before citing one code's wording under another) |

## Direct answer

Hazardous location is a defined term in the International Residential Code (IRC) 2009, in Fuel Gas. The code's own words are: “Any location considered to be a fire hazard for flammable vapors, dust, combustible fibers or other highly combustible substances. The location is not necessarily categorized in the International BUilding Code as a high-hazard use group classification.” The IMC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 16 chapters of this corpus, most often in Flammable Finishes (IFC 2009), Glass and Glazing (IBC 2009), Fire and Smoke Protection Features (IBC 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?

**Hazardous Location** — IRC 2009, Fuel Gas:

> Any location considered to be a fire hazard for flammable vapors, dust, combustible fibers or other highly combustible substances. The location is not necessarily categorized in the International BUilding Code as a high-hazard use group classification.

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

*How the IRC 2009, IMC 2009 define hazardous location, 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 **Hazardous Location**, in identical words.

| Code | Where it is defined | Definition |
| --- | --- | --- |
| IRC 2009 | [Fuel Gas](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/fuel-gas.md) | Any location considered to be a fire hazard for flammable vapors, dust, combustible fibers or other highly combustible substances. The location is not necessarily categorized in the International BUilding Code as a high-hazard use group classification. |
| IMC 2009 | [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/definitions.md) | Any location considered to be a fire hazard for flammable vapors, dust, combustible fibers or other highly combustible substances. The location is not necessarily categorized in the International Building Code as a high-hazard use group classification. |

## Where hazardous location is used in the code

The term appears in 16 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 Finishes](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-finishes.md) | IFC 2009 | 19 |
| [Glass and Glazing](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/glass-and-glazing.md) | IBC 2009 | 7 |
| [Fire and Smoke Protection Features](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md) | IBC 2009 | 5 |
| [Refrigeration](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/refrigeration.md) | IMC 2009 | 5 |
| [Building Planning](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/building-planning.md) | IRC 2009 | 4 |
| [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 | 3 |
| [General Regulations](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/general-regulations.md) | IMC 2009 | 3 |
| [Flammable Solids](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-solids.md) | IFC 2009 | 2 |
| [Semiconductor Fabrication Facilities](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/semiconductor-fabrication-facilities.md) | IFC 2009 | 2 |
| [Specific Appliances, Fireplaces and Solid Fuel-burning Equipment](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/specific-appliances-fireplaces-and-solid-fuel-burning-equipment.md) | IMC 2009 | 2 |
| [Fuel Gas](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/fuel-gas.md) | IRC 2009 | 2 |
| [Building Services and Systems](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/building-services-and-systems.md) | IFC 2009 | 1 |

_4 further chapters mention the term._

### The term in use

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

> Where refrigerants of Groups A2, A3, B2 and B3 are used, the machinery room shall conform to the Class 1, Division 2, hazardous location classification requirements of NFPA 70.

— [IMC 2009 §1106.4](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/refrigeration.md)

> Appliances shall not be located in a hazardous location unless listed and approved for the specific installation.

— [IMC 2009 §303.2](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/general-regulations.md)

> Where refrigerants of Groups A2, A3, B2 and B3, as defined in the International Mechanical Code, are used, refrigeration machinery rooms shall conform to the Class I, Division 2 hazardous location classification requirements of NFPA 70.

— [IFC 2009 §606.16](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/building-services-and-systems.md)


## The terms hazardous location is built out of

The definition above leans on 2 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what hazardous location covers:

- **[Combustible Fibers](https://harth.build/resources/glossary/combustible-fibers.md)** — IBC 2009: Readily ignitable and free-burning materials in a fibrous or shredded form, such as cocoa fiber, cloth, cotton, excelsior, hay, hemp, henequen, istle,jute, kapok, oakum, rags, sisal, Spanish moss, straw, tow, wastepaper, certain synthetic fibers or other like materials.
- **[Building](https://harth.build/resources/glossary/building.md)** — IBC 2009: Any structure used or intended for supporting or sheltering any use or occupancy.

## Hazardous Location: 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 IRC | Fuel Gas | |
| Read the definition in the adopted IMC | Definitions | |
| Re-check the requirement that uses it | Flammable Finishes (IFC 2009) | |
| Re-check the requirement that uses it | Glass and Glazing (IBC 2009) | |
| Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 2009) | |
| Re-check the requirement that uses it | Refrigeration (IMC 2009) | |
| Confirm the dependent definition | Combustible Fibers | |
| Confirm the dependent definition | Building | |
| 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)
- [Combustible Fibers: Building Code Definition](https://harth.build/resources/glossary/combustible-fibers.md)
- [Building: Building Code Definition](https://harth.build/resources/glossary/building.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 hazardous location?

The International Residential Code (IRC) 2009 defines it in Fuel Gas as: “Any location considered to be a fire hazard for flammable vapors, dust, combustible fibers or other highly combustible substances. The location is not necessarily categorized in the International BUilding Code as a high-hazard use group classification.” 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 hazardous location?

In this corpus the term is used across 16 chapters, led by Flammable Finishes 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 hazardous location?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Fuel Gas: “Any location considered to be a fire hazard for flammable vapors, dust, combustible fibers or other highly combustible substances. The location is not necessarily categorized in the International BUilding Code as a high-hazard use group classification.” 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.

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