Building Code Glossary
Building Line: Building Code Definition
How the IBC 2009, IRC 2009 define building line, 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
Building line is a defined term in the International Building Code (IBC) 2009, in Definitions. The code's own words are: “The line established by law, beyond which a building shall not extend, except as specifically provided by law.” The IRC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 3 chapters of this corpus, most often in Definitions (IBC 2009), Existing Structures (IBC 2009), Definitions (IRC 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?
Building Line — IBC 2009, Definitions:
The line established by law, beyond which a building shall not extend, except as specifically provided by law.
What must be verified before using this guidance?
Two of the I-Codes in this corpus define Building Line, in identical words.
| Code | Where it is defined | Definition |
|---|---|---|
| IBC 2009 | Definitions | The line established by law, beyond which a building shall not extend, except as specifically provided by law. |
| IRC 2009 | Definitions | The line established by law, beyond which a building shall not extend, except as specifically provided by law. |
Where building line 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 |
|---|---|---|
| Definitions | IBC 2009 | 1 |
| Existing Structures | IBC 2009 | 1 |
| Definitions | IRC 2009 | 1 |
The term in use
How the code actually writes about building line, quoted from the 2009 text hosted here:
Where located on the front of the building and where projecting beyond the building line, the lowest landing shall not be less than 7 feet (2134 mm) or more than 12 feet (3658 mm) above grade, and shall be equipped with a counter-balanced stairway to the street.
The terms building line 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 building line 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.
Building Line: 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 | |
| Re-check the requirement that uses it | Definitions (IBC 2009) | |
| Re-check the requirement that uses it | Existing Structures (IBC 2009) | |
| Re-check the requirement that uses it | Definitions (IRC 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
- Construction Documents: Building Code Definition
- Registered Design Professional: Building Code Definition
- Dwelling Unit: 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 building line?
The International Building Code (IBC) 2009 defines it in Definitions as: “The line established by law, beyond which a building shall not extend, except as specifically provided by law.” 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 building line?
In this corpus the term is used across 3 chapters, led by Definitions 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 building line mean on a survey?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Definitions: “The line established by law, beyond which a building shall not extend, except as specifically provided by law.” It is defined in IBC 2009, IRC 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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