# Building, Existing: Building Code Definition

> How the IRC 2009 define building, existing, where the wording differs, and which chapters depend on the term.

- Canonical: https://harth.build/resources/glossary/building-existing/
- 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 | IRC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IRC 2009 Definitions (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 31 (counted across the codes hosted here) |
| Wording identical across codes | Single code (compare before citing one code's wording under another) |

## Direct answer

Building, existing is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “Existing building is a building erected prior to the adoption of this code, or one for which a legal building permit has been issued.” No other I-Code in this corpus defines it, so the IRC 2009 definition is the one to work from. The term is used in 31 chapters of this corpus, most often in Existing Structures (IBC 2009), Construction Requirements for Existing Buildings (IFC 2009), Interior Finish, Decorative Materials and Furnishings (IFC 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?

**Building, Existing** — IRC 2009, Definitions:

> Existing building is a building erected prior to the adoption of this code, or one for which a legal building permit has been issued.

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

*How the IRC 2009 define building, existing, where the wording differs, and which chapters depend on the term.*

## What must be verified before using this guidance?

**Building, Existing** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) chapter of the International Residential Code (IRC) 2009:

> Existing building is a building erected prior to the adoption of this code, or one for which a legal building permit has been issued.

## Where building, existing is used in the code

The term appears in 31 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

| Chapter | Code | Mentions |
| --- | --- | --- |
| [Existing Structures](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/existing-structures.md) | IBC 2009 | 64 |
| [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 | 24 |
| [Interior Finish, Decorative Materials and Furnishings](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/interior-finish-decorative-materials-and-furnishings.md) | IFC 2009 | 21 |
| [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-protection-systems.md) | IFC 2009 | 15 |
| [Administration](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/administration.md) | IECC 2009 | 12 |
| [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-protection-systems.md) | IBC 2009 | 8 |
| [Safeguards During Construction](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/safeguards-during-construction.md) | IBC 2009 | 6 |
| [Semiconductor Fabrication Facilities](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/semiconductor-fabrication-facilities.md) | IFC 2009 | 6 |
| [Scope and Administration](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/scope-and-administration.md) | IRC 2009 | 6 |
| [Accessibility](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/accessibility.md) | IBC 2009 | 4 |
| [Means of Egress](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/means-of-egress.md) | IBC 2009 | 4 |
| [Fire Service Features](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-service-features.md) | IFC 2009 | 4 |

_19 further chapters mention the term._

### The term in use

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

> Work performed in accordance with the International Existing Building Code shall be deemed to comply with the provisions of this chapter.

— [IBC 2009 §3401.4](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/existing-structures.md)

> Except as specified in this chapter, this code shall not be used to require the removal, alteration or abandonment of, nor prevent the continued use and maintenance of, an existing building or building system lawfully in existence at the time of adoption of this code.

— [IECC 2009 §101.4.1](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/administration.md)

> Where a building has been constructed to a bUildingheightof 50 feet (15 240 mm) or four stories, or where an existing building exceeding 50 feet (15 240 mm) in bUildingheight is altered, at least one temporary lighted stairway shall be provided unless one or more of the permanent stairways are erected as the construction progresses.

— [IBC 2009 §3310.1](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/safeguards-during-construction.md)


## Building, Existing compared with Existing Structure

These two are the closest pair in the 2009 I-Codes: about 75 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 |
| --- | --- |
| **Building, Existing** (IRC 2009) | existing |
| [Existing Structure](https://harth.build/resources/glossary/existing-structure.md) (IBC 2009) | structure, date, appropriate |

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 building, existing and existing structure.

## The terms building, existing 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 building, existing covers:

- **[Building](https://harth.build/resources/glossary/building.md)** — IBC 2009: Any structure used or intended for supporting or sheltering any use or occupancy.
- **[Existing](https://harth.build/resources/glossary/existing.md)** — IFC 2009: Buildings, facilities or conditions that are already in existence, constructed or officially authorized prior to the adoption of this code.
- **[Permit](https://harth.build/resources/glossary/permit.md)** — IBC 2009: An official document or certificate issued by the authority having jurisdiction which authorizes performance of a specified activity.

## Building, Existing: 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 IRC | Definitions | |
| Re-check the requirement that uses it | Existing Structures (IBC 2009) | |
| Re-check the requirement that uses it | Construction Requirements for Existing Buildings (IFC 2009) | |
| Re-check the requirement that uses it | Interior Finish, Decorative Materials and Furnishings (IFC 2009) | |
| Re-check the requirement that uses it | Fire Protection Systems (IFC 2009) | |
| Confirm the dependent definition | Building | |
| Confirm the dependent definition | Existing | |
| Confirm the dependent definition | Permit | |
| 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)
- [Existing: Building Code Definition](https://harth.build/resources/glossary/existing.md)
- [Building: Building Code Definition](https://harth.build/resources/glossary/building.md)
- [Permit: Building Code Definition](https://harth.build/resources/glossary/permit.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 building, existing?

The International Residential Code (IRC) 2009 defines it in Definitions as: “Existing building is a building erected prior to the adoption of this code, or one for which a legal building permit has been issued.” 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, existing?

In this corpus the term is used across 31 chapters, led by Existing 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 is the definition of an existing building?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “Existing building is a building erected prior to the adoption of this code, or one for which a legal building permit has been issued.” It is defined in 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.

---

- Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fbuilding-existing%2F
- View this page in a browser: https://harth.build/resources/glossary/building-existing/
- All resources for agents: https://harth.build/llms.txt