# Penthouse: Building Code Definition

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

- Canonical: https://harth.build/resources/glossary/penthouse/
- 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, IFC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IBC 2009 Roof Assemblies and Rooftop Structures (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 8 (counted across the codes hosted here) |
| Wording identical across codes | Yes (compare before citing one code's wording under another) |

## Direct answer

Penthouse is a defined term in the International Building Code (IBC) 2009, in Roof Assemblies and Rooftop Structures. The code's own words are: “An enclosed, unoccupied structure above the roof of a building, other than a tank, tower, spire, dome cupola or bulkhead.” The IFC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 8 chapters of this corpus, most often in Roof Assemblies and Rooftop Structures (IBC 2009), Refrigeration (IMC 2009), Means of Egress (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](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?

**Penthouse** — IBC 2009, Roof Assemblies and Rooftop Structures:

> An enclosed, unoccupied structure above the roof of a building, other than a tank, tower, spire, dome cupola or bulkhead.

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

*How the IBC 2009, IFC 2009 define penthouse, 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 **Penthouse**, in identical words.

| Code | Where it is defined | Definition |
| --- | --- | --- |
| IBC 2009 | [Roof Assemblies and Rooftop Structures](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/roof-assemblies-and-rooftop-structures.md) | An enclosed, unoccupied structure above the roof of a building, other than a tank, tower, spire, dome cupola or bulkhead. |
| IFC 2009 | [Definitions](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/definitions.md) | An enclosed, unoccupied structure above the roof of a building, other than a tank, tower, spire, dome cupola or bulkhead. |

## Where penthouse is used in the code

The term appears in 8 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

| Chapter | Code | Mentions |
| --- | --- | --- |
| [Roof Assemblies and Rooftop Structures](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/roof-assemblies-and-rooftop-structures.md) | IBC 2009 | 27 |
| [Refrigeration](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/refrigeration.md) | IMC 2009 | 6 |
| [Means of Egress](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/means-of-egress.md) | IBC 2009 | 3 |
| [Means of Egress](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/means-of-egress.md) | IFC 2009 | 3 |
| [Accessibility](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/accessibility.md) | IBC 2009 | 2 |
| [General Requirements](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/general-requirements.md) | IFC 2009 | 2 |
| [Definitions](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/definitions.md) | IBC 2009 | 1 |
| [Definitions](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/definitions.md) | IFC 2009 | 1 |

### The term in use

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

> A penthouse or penthouses in compliance with Sections 1509.2.1 through 1509.2.4 shall be considered as a portion of the story below.

— [IBC 2009 §1509.2](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/roof-assemblies-and-rooftop-structures.md)

> Where a stairway is provided to a roof, access to the roof shall be provided through a penthouse complying with Section 1509.2.

— [IBC 2009 §1009.13.1](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/means-of-egress.md)


## Penthouse compared with Rooftop Structure

These two are the closest pair in the 2009 I-Codes: about 45 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 |
| --- | --- |
| **Penthouse** (IBC 2009) | unoccupied, tank, tower, spire, dome, cupola, bulkhead |
| [Rooftop Structure](https://harth.build/resources/glossary/rooftop-structure.md) (IBC 2009) | part |

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 penthouse and rooftop structure.

## The terms penthouse is built out of

The definition above leans on 3 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what penthouse covers:

- **[Structure](https://harth.build/resources/glossary/structure.md)** — IPC 2009: That which is built or constructed or a portion thereof.
- **[Building](https://harth.build/resources/glossary/building.md)** — IBC 2009: Any structure used or intended for supporting or sheltering any use or occupancy.
- **[Enclosed](https://harth.build/resources/glossary/enclosed.md)** — IRC 2009: Surrounded by a case, housing, fence or walls that will prevent persons from accidentally contacting energized parts.

## Penthouse: 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 | Roof Assemblies and Rooftop Structures | |
| Read the definition in the adopted IFC | Definitions | |
| Re-check the requirement that uses it | Roof Assemblies and Rooftop Structures (IBC 2009) | |
| Re-check the requirement that uses it | Refrigeration (IMC 2009) | |
| Re-check the requirement that uses it | Means of Egress (IBC 2009) | |
| Re-check the requirement that uses it | Means of Egress (IFC 2009) | |
| Confirm the dependent definition | Structure | |
| 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?

- [Explore all glossary guidance](https://harth.build/resources/glossary.md)
- [Structure: Building Code Definition](https://harth.build/resources/glossary/structure.md)
- [Enclosed: Building Code Definition](https://harth.build/resources/glossary/enclosed.md)
- [Building: Building Code Definition](https://harth.build/resources/glossary/building.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 penthouse?

The International Building Code (IBC) 2009 defines it in Roof Assemblies and Rooftop Structures as: “An enclosed, unoccupied structure above the roof of a building, other than a tank, tower, spire, dome cupola or bulkhead.” 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 penthouse?

In this corpus the term is used across 8 chapters, led by Roof Assemblies and Rooftop Structures 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 IBC mean in building codes?

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 penthouse, which the IBC 2009 defines as “An enclosed, unoccupied structure above the roof of a building, other than a tank, tower, spire, dome cupola or bulkhead.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

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