Building Code Glossary
Shaft: Building Code Definition
How the IBC 2009, IRC 2009, IMC 2009 define shaft, 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
Shaft is a defined term in the International Building Code (IBC) 2009, in Fire and Smoke Protection Features. The code's own words are: “An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and roof.” The IRC 2009, IMC 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 32 chapters of this corpus, most often in Fire and Smoke Protection Features (IBC 2009), Soils and Foundations (IBC 2009), Duct Systems (IMC 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?
Shaft — IBC 2009, Fire and Smoke Protection Features:
An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and roof.
What must be verified before using this guidance?
Three of the I-Codes in this corpus define Shaft, and the wording is not identical — read the version that governs your question.
| Code | Where it is defined | Definition |
|---|---|---|
| IBC 2009 | Fire and Smoke Protection Features | An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and roof. |
| IRC 2009 | Fuel Gas | An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and the roof. |
| IMC 2009 | Definitions | An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and the roof. |
Where shaft is used in the code
The term appears in 32 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 | 178 |
| Soils and Foundations | IBC 2009 | 56 |
| Duct Systems | IMC 2009 | 53 |
| Fire Protection Systems | IBC 2009 | 39 |
| Special Detailed Requirements Based on Use and Occupancy | IBC 2009 | 28 |
| Exhaust Systems | IMC 2009 | 24 |
| General Requirements | IFC 2009 | 20 |
| Refrigeration | IMC 2009 | 12 |
| Elevators and Conveying Systems | IBC 2009 | 11 |
| Means of Egress | IBC 2009 | 10 |
| Means of Egress | IFC 2009 | 9 |
| Fire-resistance-rated Construction | IFC 2009 | 8 |
20 further chapters mention the term.
The term in use
How the code actually writes about shaft, quoted from the 2009 text hosted here:
The fire-resistance rating of the fire barrierseparating building areas from a shaft shall comply with Section 708.4.
The moments, shears and lateral deflections used for design of deep foundation elements shall be established considering the nonlinear interaction of the shaft and soil, as determined by a registered design professional.
Ducts that penetrate horizontal assemblies not required to be contained within a shaft and not required by this section to have dampers shall comply with the requirements of Sections 713.4 through 713.4.2.2 of the International Building Code.
The terms shaft 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 shaft covers:
- Building — IBC 2009: Any structure used or intended for supporting or sheltering any use or occupancy.
- Enclosed — IRC 2009: Surrounded by a case, housing, fence or walls that will prevent persons from accidentally contacting energized parts.
Shaft: 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 | |
| Read the definition in the adopted IRC | Fuel Gas | |
| Read the definition in the adopted IMC | Definitions | |
| Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 2009) | |
| Re-check the requirement that uses it | Soils and Foundations (IBC 2009) | |
| Re-check the requirement that uses it | Duct Systems (IMC 2009) | |
| Re-check the requirement that uses it | Fire Protection Systems (IBC 2009) | |
| Confirm the dependent definition | Building | |
| Confirm the dependent definition | Enclosed | |
| 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?
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 shaft?
The International Building Code (IBC) 2009 defines it in Fire and Smoke Protection Features as: “An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and roof.” 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.
Do the I-Codes define shaft the same way?
No. IBC 2009, IRC 2009, IMC 2009 all define the term, but the wording is not identical, and a difference in wording can change which requirements are triggered. The comparison table above sets the versions side by side so you can read the one that governs your question.
Which parts of the code depend on shaft?
In this corpus the term is used across 32 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 a shaft in a building?
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: “An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and roof.” It is defined in IBC 2009, IRC 2009, IMC 2009. It is not the same as Building, which the IBC 2009 defines separately as “Any structure used or intended for supporting or sheltering any use or occupancy.” 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 "shaft" 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: “An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and roof.” It is defined in IBC 2009, IRC 2009, IMC 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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