Building Code Glossary
Attic: Building Code Definition
How the IBC 2009, IRC 2009, IFC 2009 define attic, 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
Attic is a defined term in the International Building Code (IBC) 2009, in Definitions. The code's own words are: “The space between the ceiling beams of the top story and the roof rafters.” The IRC 2009 words it differently, in Definitions: “The unfinished space between the ceiling assembly of the top story and the roof assembly.” 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 45 chapters of this corpus, most often in Wall Construction (IRC 2009), Building Planning (IRC 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, Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.
What does this term mean?
Attic — IBC 2009, Definitions:
The space between the ceiling beams of the top story and the roof rafters.
What must be verified before using this guidance?
Three of the I-Codes in this corpus define Attic, and the wording is not identical — read the version that governs your question.
| Code | Where it is defined | Definition |
|---|---|---|
| IBC 2009 | Definitions | The space between the ceiling beams of the top story and the roof rafters. |
| IRC 2009 | Definitions | The unfinished space between the ceiling assembly of the top story and the roof assembly. |
| IFC 2009 | Definitions | The space between the ceiling beams of the top story and the roof rafters. |
Where attic is used in the code
The term appears in 45 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Wall Construction | IRC 2009 | 121 |
| Building Planning | IRC 2009 | 29 |
| Fire and Smoke Protection Features | IBC 2009 | 27 |
| Roof-ceiling Construction | IRC 2009 | 23 |
| Fuel Gas | IRC 2009 | 20 |
| Energy Efficiency | IRC 2009 | 16 |
| Fire Protection Systems | IFC 2009 | 15 |
| Exhaust Systems | IRC 2009 | 15 |
| Fire Protection Systems | IBC 2009 | 14 |
| Construction Requirements for Existing Buildings | IFC 2009 | 14 |
| Floors | IRC 2009 | 13 |
| Interior Environment | IBC 2009 | 12 |
33 further chapters mention the term.
The term in use
How the code actually writes about attic, quoted from the 2009 text hosted here:
All exposed insulation materials installed on attic floors shall have a critical radiant flux not less than 0.12 watt per square centimeter.
In I-hour fire-resistance-rated roof assemblies, the floor membrane is not required to be installed where unusable attic space occurs above.
Buildings with combustible ceiling or roof construction shall have an attic access opening to attic areas that exceed 30 square feet (2.8 m2) and have a vertical height of 30 inches (762 mm) or greater.
The terms attic 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 attic covers:
- Roof Assembly — IBC 2009: A system designed to provide weather protection and resistance to design loads.
- Story — IBC 2009: That portion ofa building included between the upper surface of a floor and the upper surface of the floor or roof next above (also see "Basement," "Mezzanine" and Section 502.1).
Attic: 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 | Definitions | |
| Read the definition in the adopted IRC | Definitions | |
| Read the definition in the adopted IFC | Definitions | |
| Re-check the requirement that uses it | Wall Construction (IRC 2009) | |
| Re-check the requirement that uses it | Building Planning (IRC 2009) | |
| Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 2009) | |
| Re-check the requirement that uses it | Roof-ceiling Construction (IRC 2009) | |
| Confirm the dependent definition | Roof Assembly | |
| Confirm the dependent definition | Story | |
| 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
- Roof Assembly: Building Code Definition
- Story: 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 attic?
The International Building Code (IBC) 2009 defines it in Definitions as: “The space between the ceiling beams of the top story and the roof rafters.” 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 attic?
In this corpus the term is used across 45 chapters, led by Wall Construction in the IRC 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 legal definition of an attic?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Definitions: “The space between the ceiling beams of the top story and the roof rafters.” 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 does IBC mean in building codes?
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 attic, which the IBC 2009 defines as “The space between the ceiling beams of the top story and the roof rafters.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
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