# Mineral Fiber: Building Code Definition

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

- Canonical: https://harth.build/resources/glossary/mineral-fiber/
- 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 (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 | 6 (counted across the codes hosted here) |
| Wording identical across codes | Single code (compare before citing one code's wording under another) |

## Direct answer

Mineral fiber is a defined term in the International Building Code (IBC) 2009, in Fire and Smoke Protection Features. The code's own words are: “Insulation composed principally of fibers manufactured from rock, slag or glass, with or without binders.” No other I-Code in this corpus defines it, so the IBC 2009 definition is the one to work from. The term is used in 6 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. 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](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?

**Mineral Fiber** — IBC 2009, Fire and Smoke Protection Features:

> Insulation composed principally of fibers manufactured from rock, slag or glass, with or without binders.

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

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

## What must be verified before using this guidance?

**Mineral Fiber** is defined once in this corpus, in the [Fire and Smoke Protection Features](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md) chapter of the International Building Code (IBC) 2009:

> Insulation composed principally of fibers manufactured from rock, slag or glass, with or without binders.

## Where mineral fiber is used in the code

The term appears in 6 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 | 11 |
| [Building Planning](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/building-planning.md) | IRC 2009 | 10 |
| [Plastic](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/plastic.md) | IBC 2009 | 6 |
| [Definitions](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/definitions.md) | IBC 2009 | 1 |
| [Roof Assemblies and Rooftop Structures](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/roof-assemblies-and-rooftop-structures.md) | IBC 2009 | 1 |
| [Roof Assemblies](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/roof-assemblies.md) | IRC 2009 | 1 |

### The term in use

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

> Batts or blankets of mineral wool or mineral fiber or other approved nonrigid materials shall be permitted for compliance with the 10-foot (3048 mm) horizontal fireblocking in walls constructed using parallel rows of studs or staggered studs.

— [IBC 2009 §717.2.1.1](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md)

> Within an attic or crawl space where entry is made only for service of utilities, foam plastic insulation shall be protected against ignition by 1 ½-inch-thick (38 mm) mineral fiber insulation;

— [IBC 2009 §2603.4.1.6](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/plastic.md)

> Where the application of a new roof covering over wood shingle or shake roofs creates a combustible concealed space, the entire existing surface shall be covered with gypsum board, mineral fiber, glass fiber or other approved materials securely fastened in place.

— [IBC 2009 §1510.4](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/roof-assemblies-and-rooftop-structures.md)

## Mineral Fiber: 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 | |
| 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 | Definitions (IBC 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)
- [Shaft: Building Code Definition](https://harth.build/resources/glossary/shaft.md)
- [Damper: Building Code Definition](https://harth.build/resources/glossary/damper.md)
- [Fire-resistance Rating: Building Code Definition](https://harth.build/resources/glossary/fire-resistance-rating.md)
- [Fire Barrier: Building Code Definition](https://harth.build/resources/glossary/fire-barrier.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 mineral fiber?

The International Building Code (IBC) 2009 defines it in Fire and Smoke Protection Features as: “Insulation composed principally of fibers manufactured from rock, slag or glass, with or without binders.” 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 mineral fiber?

In this corpus the term is used across 6 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 an example of a mineral fiber?

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: “Insulation composed principally of fibers manufactured from rock, slag or glass, with or without binders.” It is defined in IBC 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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