Building Code Glossary
Mineral Wool: Building Code Definition
How the IBC 2009 define mineral wool, 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
Mineral wool is a defined term in the International Building Code (IBC) 2009, in Fire and Smoke Protection Features. The code's own words are: “Synthetic vitreous fiber insulation made by melting predominately igneous rock or furnace slag, and other inorganic materials, and then physically forming the melt into fibers.” 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 3 chapters of this corpus, most often in Fire and Smoke Protection Features (IBC 2009), Building Planning (IRC 2009), Definitions (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, Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.
What does this term mean?
Mineral Wool — IBC 2009, Fire and Smoke Protection Features:
Synthetic vitreous fiber insulation made by melting predominately igneous rock or furnace slag, and other inorganic materials, and then physically forming the melt into fibers.
What must be verified before using this guidance?
Mineral Wool is defined once in this corpus, in the Fire and Smoke Protection Features chapter of the International Building Code (IBC) 2009:
Synthetic vitreous fiber insulation made by melting predominately igneous rock or furnace slag, and other inorganic materials, and then physically forming the melt into fibers.
Where mineral wool is used in the code
The term appears in 3 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 | IBC 2009 | 25 |
| Building Planning | IRC 2009 | 7 |
| Definitions | IBC 2009 | 1 |
The term in use
How the code actually writes about mineral wool, 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.
Bya horizontal distance of not less than the depth of the wall cavity where the wall cavity is filled with cellulose loose-fill, rockwool or slag mineral wool insulation;
— IBC 2009, Fire and Smoke Protection Features
By a horizontal distance of not less than the depth of the wall cavity when the wall cavity is filled with cellulose loose-fill, rockwool or slag mineral wool insulation;
The terms mineral wool 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 mineral wool covers:
- Furnace — IRC 2009: A completely self-contained heating unit that is designed to supply heated air to spaces remote from or adjacent to the appliance location.
Mineral Wool: 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 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 | Definitions (IBC 2009) | |
| Confirm the dependent definition | Furnace | |
| 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
- Furnace: Building Code Definition
- Shaft: Building Code Definition
- Damper: Building Code Definition
- Fire-resistance Rating: 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 mineral wool?
The International Building Code (IBC) 2009 defines it in Fire and Smoke Protection Features as: “Synthetic vitreous fiber insulation made by melting predominately igneous rock or furnace slag, and other inorganic materials, and then physically forming the melt into fibers.” 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 wool?
In this corpus the term is used across 3 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 does mineral wool mean?
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: “Synthetic vitreous fiber insulation made by melting predominately igneous rock or furnace slag, and other inorganic materials, and then physically forming the melt into fibers.” 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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