# Shall: Building Code Definition

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

- Canonical: https://harth.build/resources/glossary/shall/
- 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 | 164 (counted across the codes hosted here) |
| Wording identical across codes | Single code (compare before citing one code's wording under another) |

## Direct answer

Shall is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “The term, when used in the code, is construed as mandatory.” 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 164 chapters of this corpus, most often in Flammable and Combustible Liquids (IFC 2009), Wall Construction (IRC 2009), Fire Protection Systems (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?

**Shall** — IRC 2009, Definitions:

> The term, when used in the code, is construed as mandatory.

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

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

## What must be verified before using this guidance?

**Shall** 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:

> The term, when used in the code, is construed as mandatory.

## Where shall is used in the code

The term appears in 164 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

| Chapter | Code | Mentions |
| --- | --- | --- |
| [Flammable and Combustible Liquids](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-and-combustible-liquids.md) | IFC 2009 | 2725 |
| [Wall Construction](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/wall-construction.md) | IRC 2009 | 2027 |
| [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-protection-systems.md) | IFC 2009 | 1821 |
| [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 | 1742 |
| [Fuel Gas](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/fuel-gas.md) | IRC 2009 | 1677 |
| [Fire and Smoke Protection Features](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md) | IBC 2009 | 1665 |
| [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-protection-systems.md) | IBC 2009 | 1609 |
| [Means of Egress](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/means-of-egress.md) | IFC 2009 | 1586 |
| [Means of Egress](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/means-of-egress.md) | IBC 2009 | 1481 |
| [Soils and Foundations](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/soils-and-foundations.md) | IBC 2009 | 1480 |
| [Exhaust Systems](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/exhaust-systems.md) | IMC 2009 | 1341 |
| [Wood](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/wood.md) | IBC 2009 | 1259 |

_152 further chapters mention the term._

### The term in use

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

> Prevention, control and mitigation of dangerous conditions related to storage, use, dispensing, mixing and handling of flammable and combustible liquids shall be in accordance with Chapter 27 and this chapter.

— [IFC 2009 §3401.1](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-and-combustible-liquids.md)

> The provisions of this chapter shall control the design and construction of all walls and partitions for all buildings.

— [IRC 2009 §R601.1](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/wall-construction.md)

> The provisions of this chapter shall specify where fire protection systems are required and shall apply to the design, installation, inspection, operation, testing and maintenance of all fire protection systems.

— [IFC 2009 §901.1](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-protection-systems.md)

## Shall: 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 | Flammable and Combustible Liquids (IFC 2009) | |
| Re-check the requirement that uses it | Wall Construction (IRC 2009) | |
| Re-check the requirement that uses it | Fire Protection Systems (IFC 2009) | |
| Re-check the requirement that uses it | Special Detailed Requirements Based on Use and Occupancy (IBC 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)
- [Building: Building Code Definition](https://harth.build/resources/glossary/building.md)
- [Construction Documents: Building Code Definition](https://harth.build/resources/glossary/construction-documents.md)
- [Registered Design Professional: Building Code Definition](https://harth.build/resources/glossary/registered-design-professional.md)
- [Dwelling Unit: Building Code Definition](https://harth.build/resources/glossary/dwelling-unit.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 shall?

The International Residential Code (IRC) 2009 defines it in Definitions as: “The term, when used in the code, is construed as mandatory.” 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 shall?

In this corpus the term is used across 164 chapters, led by Flammable and Combustible Liquids in the IFC 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 legal definition of "shall"?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “The term, when used in the code, is construed as mandatory.” 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.

### What does IRC mean in building code?

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 shall, which the IRC 2009 defines as “The term, when used in the code, is construed as mandatory.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

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