# Fireblocking: Building Code Definition

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

- Canonical: https://harth.build/resources/glossary/fireblocking/
- 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, IRC 2009, IFC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IBC 2009 Fire and Smoke Protection Features (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 20 (counted across the codes hosted here) |
| Wording identical across codes | No (compare before citing one code's wording under another) |

## Direct answer

Fireblocking is a defined term in the International Building Code (IBC) 2009, in Fire and Smoke Protection Features. The code's own words are: “Building materials or materials for use as fireblocking, installed to resist the free passage of flame to other areas of the building through concealed spaces.” The IRC 2009, IFC 2009 define the same term with different wording, so the controlling text depends on which code governs the question in front of you — the comparison below sets the versions side by side. The term is used in 20 chapters of this corpus, most often in Fire and Smoke Protection Features (IBC 2009), Building Planning (IRC 2009), Plastic (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?

**Fireblocking** — IBC 2009, Fire and Smoke Protection Features:

> Building materials or materials for use as fireblocking, installed to resist the free passage of flame to other areas of the building through concealed spaces.

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

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

## What must be verified before using this guidance?

Three of the I-Codes in this corpus define **Fireblocking**, and the wording is not identical — read the version that governs your question.

| Code | Where it is defined | Definition |
| --- | --- | --- |
| IBC 2009 | [Fire and Smoke Protection Features](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md) | Building materials or materials for use as fireblocking, installed to resist the free passage of flame to other areas of the building through concealed spaces. |
| IRC 2009 | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) | Building materials or materials approved for use as fireblocking, installed to resist the free passage of flame to other areas ofthe building through concealed spaces. |
| IFC 2009 | [Fire-resistance-rated Construction](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-resistance-rated-construction.md) | Building materials, or materials approved for use as fireblocking, installed to resist the free passage of flame to other areas of the building through concealed spaces. |

## Where fireblocking is used in the code

The term appears in 20 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

| Chapter | Code | Mentions |
| --- | --- | --- |
| [Fire and Smoke Protection Features](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md) | IBC 2009 | 64 |
| [Building Planning](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/building-planning.md) | IRC 2009 | 22 |
| [Plastic](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/plastic.md) | IBC 2009 | 8 |
| [Fuel Gas](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/fuel-gas.md) | IRC 2009 | 7 |
| [Masonry](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/masonry.md) | IBC 2009 | 6 |
| [Chimneys and Vents](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/chimneys-and-vents.md) | IMC 2009 | 6 |
| [Fire-resistance-rated Construction](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-resistance-rated-construction.md) | IFC 2009 | 4 |
| [Chimneys and Fireplaces](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/chimneys-and-fireplaces.md) | IRC 2009 | 4 |
| [Scope and Administration](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/scope-and-administration.md) | IMC 2009 | 3 |
| [Scope and Administration](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/scope-and-administration.md) | IPC 2009 | 3 |
| [Exterior Walls](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/exterior-walls.md) | IBC 2009 | 2 |
| [Scope and Administration](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/scope-and-administration.md) | IBC 2009 | 2 |

_8 further chapters mention the term._

### The term in use

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

> Where combustible members frame into hollow walls or walls of hollow units, hollow spaces shall be solidly filled for the full thickness of the wall and for a distance not less than 4 inches (102 mm) above, below and between the structural members, with noncombustible materials approved for fireblocking.

— [IBC 2009 §706.7](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md)

> In combustible construction, fireblocking shall be provided to cut off all concealed draft openings (both vertical and horizontal) and to form an effective fire barrier between stories, and between a top story and the roof space.

— [IRC 2009 §R302.11](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/building-planning.md)

> Noncombustible fireblocking shall be provided in accordance with Chapter 10.

— [IRC 2009 §G2425.15.4.1](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/fuel-gas.md)


## The terms fireblocking is built out of

The definition above leans on 3 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what fireblocking covers:

- **[Concealed](https://harth.build/resources/glossary/concealed.md)** — IRC 2009: Rendered inaccessible by the structure or finish of the building.
- **[Building](https://harth.build/resources/glossary/building.md)** — IBC 2009: Any structure used or intended for supporting or sheltering any use or occupancy.
- **[Approved](https://harth.build/resources/glossary/approved.md)** — IBC 2009: Acceptable to the code official or authority having jurisdiction.

## Fireblocking: 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 | Fire and Smoke Protection Features | |
| Read the definition in the adopted IRC | Definitions | |
| Read the definition in the adopted IFC | Fire-resistance-rated Construction | |
| Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 2009) | |
| Re-check the requirement that uses it | Building Planning (IRC 2009) | |
| Re-check the requirement that uses it | Plastic (IBC 2009) | |
| Re-check the requirement that uses it | Fuel Gas (IRC 2009) | |
| Confirm the dependent definition | Concealed | |
| Confirm the dependent definition | Building | |
| Confirm the dependent definition | Approved | |
| 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)
- [Concealed: Building Code Definition](https://harth.build/resources/glossary/concealed.md)
- [Building: Building Code Definition](https://harth.build/resources/glossary/building.md)
- [Approved: Building Code Definition](https://harth.build/resources/glossary/approved.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 fireblocking?

The International Building Code (IBC) 2009 defines it in Fire and Smoke Protection Features as: “Building materials or materials for use as fireblocking, installed to resist the free passage of flame to other areas of the building through concealed spaces.” 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 fireblocking?

In this corpus the term is used across 20 chapters, led by Fire and Smoke Protection Features in the IBC 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 purpose of fireblocking?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Fire and Smoke Protection Features: “Building materials or materials for use as fireblocking, installed to resist the free passage of flame to other areas of the building through concealed spaces.” It is defined in IBC 2009, IRC 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.

### What are the requirements for fire blocking in California 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 fireblocking, which the IBC 2009 defines as “Building materials or materials for use as fireblocking, installed to resist the free passage of flame to other areas of the building through concealed spaces.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

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