# Stair: Building Code Definition

> How the IBC 2009, IRC 2009, IFC 2009 define stair, where the wording differs, and which chapters depend on the term.

- Canonical: https://harth.build/resources/glossary/stair/
- Last updated: 2026-09-07
- Data source: 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.

## Key facts

| Fact | Value |
| --- | --- |
| Defined in | IBC 2009, IRC 2009, IFC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IBC 2009 Means of Egress (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 45 (counted across the codes hosted here) |
| Wording identical across codes | Yes (compare before citing one code's wording under another) |

## Direct answer

Stair is a defined term in the International Building Code (IBC) 2009, in Means of Egress. The code's own words are: “A change in elevation, consisting of one or more risers.” The IRC 2009, IFC 2009 carry the same definition word for word, so the term means the same thing in each. The term is used in 45 chapters of this corpus, most often in Means of Egress (IBC 2009), Means of Egress (IFC 2009), Building Planning (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](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.*

## What does this term mean?

**Stair** — IBC 2009, Means of Egress:

> A change in elevation, consisting of one or more risers.

![Labeled code-term definition diagram: Stair: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/stair/diagram-1344.webp)

*How the IBC 2009, IRC 2009, IFC 2009 define stair, where the wording differs, and which chapters depend on the term.*

## What must be verified before using this guidance?

Three of the I-Codes in this corpus define **Stair**, in identical words.

| Code | Where it is defined | Definition |
| --- | --- | --- |
| IBC 2009 | [Means of Egress](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/means-of-egress.md) | A change in elevation, consisting of one or more risers. |
| IRC 2009 | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) | A change in elevation, consisting of one or more risers. |
| IFC 2009 | [Means of Egress](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/means-of-egress.md) | A change in elevation, consisting of one or more risers. |

## Where stair 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 |
| --- | --- | --- |
| [Means of Egress](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/means-of-egress.md) | IBC 2009 | 486 |
| [Means of Egress](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/means-of-egress.md) | IFC 2009 | 416 |
| [Building Planning](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/building-planning.md) | IRC 2009 | 164 |
| [Construction Requirements for Existing Buildings](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/construction-requirements-for-existing-buildings.md) | IFC 2009 | 99 |
| [Special Detailed Requirements Based on Use and Occupancy](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/special-detailed-requirements-based-on-use-and-occupancy.md) | IBC 2009 | 87 |
| [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-protection-systems.md) | IBC 2009 | 68 |
| [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-protection-systems.md) | IFC 2009 | 34 |
| [Existing Structures](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/existing-structures.md) | IBC 2009 | 29 |
| [Fire and Smoke Protection Features](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md) | IBC 2009 | 26 |
| [Safeguards During Construction](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/safeguards-during-construction.md) | IBC 2009 | 12 |
| [Glass and Glazing](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/glass-and-glazing.md) | IBC 2009 | 10 |
| [Definitions](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/definitions.md) | IFC 2009 | 10 |

_33 further chapters mention the term._

### The term in use

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

> The 12-inch (305 mm) dimension shall be measured from the widest point of the clear stair width at the walking surface of the winder.

— [IBC 2009 §1009.3](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/means-of-egress.md)

> Stair treads and risers shall comply with Sections 1009.4.1 through 1009.4.5.

— [IFC 2009 §1009.4](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/means-of-egress.md)

> Enclosed accessible space under stairs shall have walls, under-stair surface and any soffits protected on the enclosed side with ½-inch (12.7 mm) gypsum board.

— [IRC 2009 §R302.7](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/building-planning.md)

## Stair: what to open, and in what order

Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) cover the middle rows.

| Check | Where | Confirmed |
| --- | --- | --- |
| Read the definition in the adopted IBC | Means of Egress | |
| Read the definition in the adopted IRC | Definitions | |
| Read the definition in the adopted IFC | Means of Egress | |
| Re-check the requirement that uses it | Means of Egress (IBC 2009) | |
| Re-check the requirement that uses it | Means of Egress (IFC 2009) | |
| Re-check the requirement that uses it | Building Planning (IRC 2009) | |
| Re-check the requirement that uses it | Construction Requirements for Existing Buildings (IFC 2009) | |
| 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](https://harth.build/resources/glossary.md)
- [Public Way: Building Code Definition](https://harth.build/resources/glossary/public-way.md)
- [Stairway: Building Code Definition](https://harth.build/resources/glossary/stairway.md)
- [Guard: Building Code Definition](https://harth.build/resources/glossary/guard.md)
- [Means OF Egress: Building Code Definition](https://harth.build/resources/glossary/means-of-egress.md)

## 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](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.

### Source links

- [codes.iccsafe.org](https://codes.iccsafe.org/codes)

- [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/)

## Frequently asked questions

### What is the code definition of stair?

The International Building Code (IBC) 2009 defines it in Means of Egress as: “A change in elevation, consisting of one or more risers.” 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 stair the same way?

In the 2009 editions transcribed here, yes: IBC 2009, IRC 2009, IFC 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 stair?

In this corpus the term is used across 45 chapters, led by Means of Egress 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 are the building codes for stairs in the US?

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 stair, which the IBC 2009 defines as “A change in elevation, consisting of one or more risers.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

### What are the IBC stair nosing requirements?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Means of Egress: “A change in elevation, consisting of one or more risers.” It is defined in IBC 2009, IRC 2009, IFC 2009. It is not the same as Nosing, which the IBC 2009 defines separately as “The leading edge of treads of stairs and of landings at the top of stairway flights.” 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 "stair" mean?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Means of Egress: “A change in elevation, consisting of one or more risers.” 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.

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