Updated 2026-09-07

Building Code Glossary

Vapor Pressure: Building Code Definition

How the IFC 2009 define vapor pressure, where the wording differs, and which chapters depend on the term.

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Last updated September 7, 2026 · 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.

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Direct answer

Vapor pressure is a defined term in the International Fire Code (IFC) 2009, in Hazardous Materials-general Provisions. The code's own words are: “The pressure exerted by a volatile fluid as determined in accordance with ASTM D 323.” No other I-Code in this corpus defines it, so the IFC 2009 definition is the one to work from. The term is used in 5 chapters of this corpus, most often in Hazardous Materials-general Provisions (IFC 2009), Refrigeration (IMC 2009), Use and Occupancy Classification (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, Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.

What does this term mean?

Vapor Pressure — IFC 2009, Hazardous Materials-general Provisions:

The pressure exerted by a volatile fluid as determined in accordance with ASTM D 323.

Labeled code-term definition diagram: Vapor Pressure: Building Code Definition — How the IFC 2009 define vapor pressure, where the wording differs, and which chapters depend on the term.

What must be verified before using this guidance?

Vapor Pressure is defined once in this corpus, in the Hazardous Materials-general Provisions chapter of the International Fire Code (IFC) 2009:

The pressure exerted by a volatile fluid as determined in accordance with ASTM D 323.

Where vapor pressure is used in the code

The term appears in 5 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

Chapter	Code	Mentions
Hazardous Materials-general Provisions	IFC 2009	2
Refrigeration	IMC 2009	2
Use and Occupancy Classification	IBC 2009	1
Definitions	IFC 2009	1
Definitions	IMC 2009	1

Vapor Pressure: what to open, and in what order

Every row is a document this term depends on. The ICC code library and the ICC adoption maps cover the middle rows.

Check	Where	Confirmed
Read the definition in the adopted IFC	Hazardous Materials-general Provisions
Re-check the requirement that uses it	Hazardous Materials-general Provisions (IFC 2009)
Re-check the requirement that uses it	Refrigeration (IMC 2009)
Re-check the requirement that uses it	Use and Occupancy Classification (IBC 2009)
Re-check the requirement that uses it	Definitions (IFC 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.

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 publishes the current model text and the ICC adoption maps show which edition a jurisdiction has adopted; those sources control.

Source links

Frequently asked questions

What is the code definition of vapor pressure?

The International Fire Code (IFC) 2009 defines it in Hazardous Materials-general Provisions as: “The pressure exerted by a volatile fluid as determined in accordance with ASTM D 323.” 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 vapor pressure?

In this corpus the term is used across 5 chapters, led by Hazardous Materials-general Provisions 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 definition of vapor pressure?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IFC 2009 states, in Hazardous Materials-general Provisions: “The pressure exerted by a volatile fluid as determined in accordance with ASTM D 323.” It is defined in IFC 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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