# Alternative Engineered Design: Building Code Definition

> How the IPC 2009 define alternative engineered design, where the wording differs, and which chapters depend on the term.

- Canonical: https://harth.build/resources/glossary/alternative-engineered-design/
- 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 | IPC 2009 (2009 editions transcribed in this corpus) |
| Primary source | IPC 2009 Definitions (model text, not a jurisdiction's adopted text) |
| Chapters using the term | 2 (counted across the codes hosted here) |
| Wording identical across codes | Single code (compare before citing one code's wording under another) |

## Direct answer

Alternative engineered design is a defined term in the International Plumbing Code (IPC) 2009, in Definitions. The code's own words are: “A plumbing system that performs in accordance with the intent of Chapters 3 through 12 and provides an equivalent level of performance for the protection of public health, safety and welfare. The system design is not specifically regulated by Chapters 3 through 12.” No other I-Code in this corpus defines it, so the IPC 2009 definition is the one to work from. The term is used in 2 chapters of this corpus, most often in Scope and Administration (IPC 2009), Definitions (IPC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted.

*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?

**Alternative Engineered Design** — IPC 2009, Definitions:

> A plumbing system that performs in accordance with the intent of Chapters 3 through 12 and provides an equivalent level of performance for the protection of public health, safety and welfare. The system design is not specifically regulated by Chapters 3 through 12.

![Labeled code-term definition diagram: Alternative Engineered Design: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/alternative-engineered-design/diagram-1344.webp)

*How the IPC 2009 define alternative engineered design, where the wording differs, and which chapters depend on the term.*

## What must be verified before using this guidance?

**Alternative Engineered Design** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) chapter of the International Plumbing Code (IPC) 2009:

> A plumbing system that performs in accordance with the intent of Chapters 3 through 12 and provides an equivalent level of performance for the protection of public health, safety and welfare. The system design is not specifically regulated by Chapters 3 through 12.

## Where alternative engineered design is used in the code

The term appears in 2 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

| Chapter | Code | Mentions |
| --- | --- | --- |
| [Scope and Administration](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/scope-and-administration.md) | IPC 2009 | 23 |
| [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) | IPC 2009 | 1 |

### The term in use

How the code actually writes about alternative engineered design, quoted from the 2009 text hosted here:

> The design, documentation, inspection, testing and approval of an alternative engineered design plumbing system shall comply with Sections 105.4.1 through 105.4.6.

— [IPC 2009 §105.4](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/scope-and-administration.md)


## The terms alternative engineered design 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 alternative engineered design covers:

- **[Plumbing System](https://harth.build/resources/glossary/plumbing-system.md)** — IRC 2009: Includes the water supply and distribution pipes, plumbing fixtures, supports and appurtenances; soil, waste and vent pipes; sanitary drains and building sewers to an approved point of disposal.
- **[Plumbing](https://harth.build/resources/glossary/plumbing.md)** — IRC 2009: For the purpose of this code, plumbing refers to those installations, repairs, maintenance and alterations regulated by Chapters 25 through 33.
- **[System](https://harth.build/resources/glossary/system.md)** — IFC 2009: An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping.

## Alternative Engineered Design: 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 IPC | Definitions | |
| Re-check the requirement that uses it | Scope and Administration (IPC 2009) | |
| Re-check the requirement that uses it | Definitions (IPC 2009) | |
| Confirm the dependent definition | Plumbing System | |
| Confirm the dependent definition | Plumbing | |
| Confirm the dependent definition | System | |
| 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)
- [Plumbing System: Building Code Definition](https://harth.build/resources/glossary/plumbing-system.md)
- [Plumbing: Building Code Definition](https://harth.build/resources/glossary/plumbing.md)
- [System: Building Code Definition](https://harth.build/resources/glossary/system.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 alternative engineered design?

The International Plumbing Code (IPC) 2009 defines it in Definitions as: “A plumbing system that performs in accordance with the intent of Chapters 3 through 12 and provides an equivalent level of performance for the protection of public health, safety and welfare. The system design is not specifically regulated by Chapters 3 through 12.” 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 alternative engineered design?

In this corpus the term is used across 2 chapters, led by Scope and Administration in the IPC 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 different types of 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 alternative engineered design, which the IPC 2009 defines as “A plumbing system that performs in accordance with the intent of Chapters 3 through 12 and provides an equivalent level of performance for the protection of public health, safety and welfare. The system design is not specifically regulated by Chapters …” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

### What is considered a structure in building code?

Structure is a separate defined term. The IPC 2009 defines it as: “That which is built or constructed or a portion thereof.” That is not the same as alternative engineered design, which the IPC 2009 defines as “A plumbing system that performs in accordance with the intent of Chapters 3 through 12 and provides an equivalent level of performance for the protection of public health, safety and welfare. The system design is not specifically regulated by Chapters …” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

### What is IPC in plumbing?

Plumbing is a separate defined term. The IRC 2009 defines it as: “For the purpose of this code, plumbing refers to those installations, repairs, maintenance and alterations regulated by Chapters 25 through 33.” That is not the same as alternative engineered design, which the IPC 2009 defines as “A plumbing system that performs in accordance with the intent of Chapters 3 through 12 and provides an equivalent level of performance for the protection of public health, safety and welfare. The system design is not specifically regulated by Chapters …” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

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