# Vacuum: Building Code Definition

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

- Canonical: https://harth.build/resources/glossary/vacuum/
- 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 | 25 (counted across the codes hosted here) |
| Wording identical across codes | Single code (compare before citing one code's wording under another) |

## Direct answer

Vacuum is a defined term in the International Plumbing Code (IPC) 2009, in Definitions. The code's own words are: “Any pressure less than that exerted by the atmosphere.” 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 25 chapters of this corpus, most often in Water Supply and Distribution (IPC 2009), Flammable Gases and Flammable Cryogenic Fluids (IFC 2009), Water Supply and Distribution (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?

**Vacuum** — IPC 2009, Definitions:

> Any pressure less than that exerted by the atmosphere.

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

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

## What must be verified before using this guidance?

**Vacuum** 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:

> Any pressure less than that exerted by the atmosphere.

## Where vacuum is used in the code

The term appears in 25 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

| Chapter | Code | Mentions |
| --- | --- | --- |
| [Water Supply and Distribution](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/water-supply-and-distribution.md) | IPC 2009 | 70 |
| [Flammable Gases and Flammable Cryogenic Fluids](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-gases-and-flammable-cryogenic-fluids.md) | IFC 2009 | 45 |
| [Water Supply and Distribution](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/water-supply-and-distribution.md) | IRC 2009 | 32 |
| [Sanitary Drainage](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/sanitary-drainage.md) | IPC 2009 | 17 |
| [Flammable and Combustible Liquids](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-and-combustible-liquids.md) | IFC 2009 | 16 |
| [Solar Systems](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/solar-systems.md) | IMC 2009 | 8 |
| [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) | IPC 2009 | 8 |
| [Fixtures, Faucets and Fixture Fittings](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/fixtures-faucets-and-fixture-fittings.md) | IPC 2009 | 5 |
| [Water Heaters](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/water-heaters.md) | IPC 2009 | 5 |
| [General Regulations](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/general-regulations.md) | IPC 2009 | 4 |
| [Special Piping and Storage Systems](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/special-piping-and-storage-systems.md) | IPC 2009 | 4 |
| [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) | IRC 2009 | 4 |

_13 further chapters mention the term._

### The term in use

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

> A low-pressure cutoff shall be installed on all booster pumps in a water pressure booster system to prevent creation of a vacuum or negative pressure on the suction side of the pump when a positive pressure of 10 psi (68.94 kPa) or less occurs on the suction side of the pump.

— [IPC 2009 §606.5.5](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/water-supply-and-distribution.md)

> The inner vessel of storage tanks in liquid hydrogen service shall be designed and constructed in accordance with Section VIII, Division 1, of the ASME Boiler and Pressure vessel Code and shall be vacuum jacketed in accordance with Section 3506.3.2.

— [IFC 2009 §3506.3.1](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/flammable-gases-and-flammable-cryogenic-fluids.md)

> Pipe-applied atmospheric-type vacuum breakers shall conform to ASSE 1001 or CSA B64.1.1.

— [IRC 2009 §P2902.3.2](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/water-supply-and-distribution.md)

## Vacuum: 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 | Water Supply and Distribution (IPC 2009) | |
| Re-check the requirement that uses it | Flammable Gases and Flammable Cryogenic Fluids (IFC 2009) | |
| Re-check the requirement that uses it | Water Supply and Distribution (IRC 2009) | |
| Re-check the requirement that uses it | Sanitary Drainage (IPC 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 vacuum?

The International Plumbing Code (IPC) 2009 defines it in Definitions as: “Any pressure less than that exerted by the atmosphere.” 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 vacuum?

In this corpus the term is used across 25 chapters, led by Water Supply and Distribution 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 does IPC mean 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 vacuum, which the IPC 2009 defines as “Any pressure less than that exerted by the atmosphere.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

### What does vacuum mean?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IPC 2009 states, in Definitions: “Any pressure less than that exerted by the atmosphere.” It is defined in IPC 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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