Building Code Glossary
Area, Building: Building Code Definition
How the IBC 2009, IFC 2009 define area, building, 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
Area, building is a defined term in the International Building Code (IBC) 2009, in General Building Heights and Areas. The code's own words are: “The area included within surrounding exterior walls (or exterior walls and fire walls) exclusive of vent shafts and courts. Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof or floor above.” The IFC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 14 chapters of this corpus, most often in General Building Heights and Areas (IBC 2009), Existing Structures (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, Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.
What does this term mean?
Area, Building — IBC 2009, General Building Heights and Areas:
The area included within surrounding exterior walls (or exterior walls and fire walls) exclusive of vent shafts and courts. Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof or floor above.
What must be verified before using this guidance?
Two of the I-Codes in this corpus define Area, Building, in identical words.
| Code | Where it is defined | Definition |
|---|---|---|
| IBC 2009 | General Building Heights and Areas | The area included within surrounding exterior walls (or exterior walls and fire walls) exclusive of vent shafts and courts. Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof or floor above. |
| IFC 2009 | Definitions | The area included within surrounding exterior walls (or exterior walls and fire walls) exclusive of vent shafts and courts. Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof or floor above. |
Where area, building is used in the code
The term appears in 14 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| General Building Heights and Areas | IBC 2009 | 57 |
| Existing Structures | IBC 2009 | 8 |
| Fire and Smoke Protection Features | IBC 2009 | 8 |
| Fire Protection Systems | IBC 2009 | 3 |
| Special Construction | IBC 2009 | 3 |
| Special Detailed Requirements Based on Use and Occupancy | IBC 2009 | 3 |
| Commercial Energy Efficiency | IECC 2009 | 3 |
| Means of Egress | IBC 2009 | 2 |
| Roof Assemblies and Rooftop Structures | IBC 2009 | 2 |
| Definitions | IFC 2009 | 2 |
| Fire Protection Systems | IFC 2009 | 2 |
| Means of Egress | IFC 2009 | 2 |
2 further chapters mention the term.
The term in use
How the code actually writes about area, building, quoted from the 2009 text hosted here:
Two or more buildings on the same lot shall be regulated as separate buildings or shall be considered as portions of one building if the bUilding height of each building and the aggregate building area of the buildings are within the limitations of table 503 as modified by Sections 504 and 506.
The value for building area shall be determined by the formula in Section 3412.6.2.2.
The pedestrian walkway shall not contribute to the bUilding area or the number of stories or height of connected buildings.
Area, Building compared with Fire Area
These two are the closest pair in the 2009 I-Codes: about 69 per cent of their defining words are the same. The code states both and compares neither, so the difference is worth naming.
| Wording unique to it | |
|---|---|
| Area, Building (IBC 2009) | exclusive, vent, shafts, courts |
| Fire Area (IBC 2009) | aggregate, enclosed, bounded, barriers, assemblies, next |
Everything else in the two definitions is shared. If a project turns on which of the two applies, those words are the whole of the test — and a local amendment that edits one of them without editing the other moves the boundary between area, building and fire area.
The terms area, building 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 area, building covers:
- Building — IBC 2009: Any structure used or intended for supporting or sheltering any use or occupancy.
- Shall — IRC 2009: The term, when used in the code, is construed as mandatory.
Area, Building: 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 | General Building Heights and Areas | |
| Read the definition in the adopted IFC | Definitions | |
| Re-check the requirement that uses it | General Building Heights and Areas (IBC 2009) | |
| Re-check the requirement that uses it | Existing Structures (IBC 2009) | |
| Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 2009) | |
| Re-check the requirement that uses it | Fire Protection Systems (IBC 2009) | |
| Confirm the dependent definition | Building | |
| Confirm the dependent definition | Shall | |
| 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
- Building: Building Code Definition
- Grade Plane: Building Code Definition
- Basement: Building Code Definition
- Height, Building: 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 area, building?
The International Building Code (IBC) 2009 defines it in General Building Heights and Areas as: “The area included within surrounding exterior walls (or exterior walls and fire walls) exclusive of vent shafts and courts. Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof or floor above.” 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 area, building?
In this corpus the term is used across 14 chapters, led by General Building Heights and Areas 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 definition of building area?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in General Building Heights and Areas: “The area included within surrounding exterior walls (or exterior walls and fire walls) exclusive of vent shafts and courts. Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof or floor above.” It is defined in IBC 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.
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