Updated 2026-09-07

Building Code Glossary

Shaft Enclosure: Building Code Definition

How the IBC 2009, IMC 2009 define shaft enclosure, where the wording differs, and which chapters depend on the term.

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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.

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Direct answer

Shaft enclosure is a defined term in the International Building Code (IBC) 2009, in Fire and Smoke Protection Features. The code's own words are: “The walls or construction forming the boundaries of a shaft.” The IMC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 12 chapters of this corpus, most often in Fire and Smoke Protection Features (IBC 2009), Duct Systems (IMC 2009), Special Detailed Requirements Based on Use and Occupancy (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?

Shaft Enclosure — IBC 2009, Fire and Smoke Protection Features:

The walls or construction forming the boundaries of a shaft.

Labeled code-term definition diagram: Shaft Enclosure: Building Code Definition — How the IBC 2009, IMC 2009 define shaft enclosure, where the wording differs, and which chapters depend on the term.

What must be verified before using this guidance?

Two of the I-Codes in this corpus define Shaft Enclosure, in identical words.

Code	Where it is defined	Definition
IBC 2009	Fire and Smoke Protection Features	The walls or construction forming the boundaries of a shaft.
IMC 2009	Definitions	The walls or construction forming the boundaries of a shaft.

Where shaft enclosure is used in the code

The term appears in 12 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	107
Duct Systems	IMC 2009	16
Special Detailed Requirements Based on Use and Occupancy	IBC 2009	10
Elevators and Conveying Systems	IBC 2009	8
Exhaust Systems	IMC 2009	4
Existing Structures	IBC 2009	2
Compressed Gases	IFC 2009	2
Fire-resistance-rated Construction	IFC 2009	2
Definitions	IBC 2009	1
Means of Egress	IBC 2009	1
Means of Egress	IFC 2009	1
Definitions	IMC 2009	1

The term in use

How the code actually writes about shaft enclosure, quoted from the 2009 text hosted here:

Openings through a floor/ceiling assembly shall be protected by a shaft enclosure complying with this section.

— IBC 2009 §708.2

Penetrations by air ducts of a floor, floor/ceiling assembly or the ceiling membrane of a roof/ceiling assembly shall be protected by a shaft enclosure that complies with Section 708 and Sections 716.6.1 through 716.6.3 of the International Building Code or shall comply with Sections 607.6.1 through 607.6.3.

— IMC 2009 §607.6

Any vertical opening shall be protected by a shaft enclosure in accordance with Section 708, or shall be in accordance with Section 408.5.1.

— IBC 2009 §408.5

The terms shaft enclosure 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 shaft enclosure covers:

Shaft — IBC 2009: An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and roof.

Shaft Enclosure: 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 IMC	Definitions
Re-check the requirement that uses it	Fire and Smoke Protection Features (IBC 2009)
Re-check the requirement that uses it	Duct Systems (IMC 2009)
Re-check the requirement that uses it	Special Detailed Requirements Based on Use and Occupancy (IBC 2009)
Re-check the requirement that uses it	Elevators and Conveying Systems (IBC 2009)
Confirm the dependent definition	Shaft
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.

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 enclosure?

The International Building Code (IBC) 2009 defines it in Fire and Smoke Protection Features as: “The walls or construction forming the boundaries of a shaft.” 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 enclosure the same way?

In the 2009 editions transcribed here, yes: IBC 2009, IMC 2009 carry the same wording, so the term means the same thing in each. Later editions do diverge on some terms, so confirm against the adopted edition rather than assuming the alignment holds.

Which parts of the code depend on shaft enclosure?

In this corpus the term is used across 12 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 the required fire rating for a shaft enclosure?

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: “The walls or construction forming the boundaries of a shaft.” It is defined in IBC 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.

What is the difference between a shaft and a duct in a building?

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 shaft enclosure, which the IBC 2009 defines as “The walls or construction forming the boundaries of a shaft.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

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