Building Code Glossary
Highly Toxic: Building Code Definition
How the IBC 2009, IFC 2009 define highly toxic, where the wording differs, and which chapters depend on the term.
On this page
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.
Direct answer
Highly toxic is a defined term in the International Building Code (IBC) 2009, in Use and Occupancy Classification. The code's own words are: “A material which produces a lethal dose or lethal concentration that falls within any of the following categories:” The IFC 2009 defines the same term with different wording, so the controlling text depends on which code governs the question in front of you — the comparison below sets the versions side by side. The term is used in 17 chapters of this corpus, most often in Highly Toxic and Toxic Materials (IFC 2009), Exhaust Systems (IMC 2009), Hazardous Materials-general Provisions (IFC 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, Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.
What does this term mean?
Highly Toxic — IBC 2009, Use and Occupancy Classification:
A material which produces a lethal dose or lethal concentration that falls within any of the following categories:
What must be verified before using this guidance?
Two of the I-Codes in this corpus define Highly Toxic, and the wording is not identical — read the version that governs your question.
| Code | Where it is defined | Definition |
|---|---|---|
| IBC 2009 | Use and Occupancy Classification | A material which produces a lethal dose or lethal concentration that falls within any of the following categories: |
| IFC 2009 | Highly Toxic and Toxic Materials | A material which produces a lethal dose or lethal concentration which falls within any ofthe following categories: |
Where highly toxic is used in the code
The term appears in 17 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Highly Toxic and Toxic Materials | IFC 2009 | 152 |
| Exhaust Systems | IMC 2009 | 54 |
| Hazardous Materials-general Provisions | IFC 2009 | 28 |
| Semiconductor Fabrication Facilities | IFC 2009 | 21 |
| Special Detailed Requirements Based on Use and Occupancy | IBC 2009 | 14 |
| Building Services and Systems | IFC 2009 | 11 |
| Fire Protection Systems | IBC 2009 | 10 |
| Use and Occupancy Classification | IBC 2009 | 5 |
| Electrical | IBC 2009 | 4 |
| Definitions | IFC 2009 | 4 |
| Fire Protection Systems | IFC 2009 | 4 |
| Structural Tests and Special Inspections | IBC 2009 | 3 |
5 further chapters mention the term.
The term in use
How the code actually writes about highly toxic, quoted from the 2009 text hosted here:
The storage and use of highly toxic and toxic materials shall comply with this chapter.
Highly toxic and toxic gases shall also comply with Section 3704.2.2.6.
Treatment systems for highly toxic and toxic gases shall comply with Chapter 37.
Highly Toxic: 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 IBC | Use and Occupancy Classification | |
| Read the definition in the adopted IFC | Highly Toxic and Toxic Materials | |
| Re-check the requirement that uses it | Highly Toxic and Toxic Materials (IFC 2009) | |
| Re-check the requirement that uses it | Exhaust Systems (IMC 2009) | |
| Re-check the requirement that uses it | Hazardous Materials-general Provisions (IFC 2009) | |
| Re-check the requirement that uses it | Semiconductor Fabrication Facilities (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.
Where can you explore related guidance?
- Explore all glossary guidance
- Corrosive: Building Code Definition
- Hazardous Materials: Building Code Definition
- Combustible Liquid: Building Code Definition
- Handling: Building Code Definition
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 highly toxic?
The International Building Code (IBC) 2009 defines it in Use and Occupancy Classification as: “A material which produces a lethal dose or lethal concentration that falls within any of the following categories:” 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 highly toxic?
In this corpus the term is used across 17 chapters, led by Highly Toxic and Toxic Materials 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 a high hazard occupancy?
Occupancy is a separate defined term. The IMC 2009 defines it as: “The purpose for which a building, or portion thereof, is utilized or occupied.” That is not the same as highly toxic, which the IBC 2009 defines as “A material which produces a lethal dose or lethal concentration that falls within any of the following categories:” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
What does the term "highly toxic" mean?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Use and Occupancy Classification: “A material which produces a lethal dose or lethal concentration that falls within any of the following categories:” It is defined in IBC 2009, 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.
Related pages
- High-piled Combustible Storage: Building Code Definition
High-piled Combustible Storage — IFC 2009 definition: Storage of combustible materials in closely packed piles or combustible materials on pallets, in racks or …
- High-piled Storage Area: Building Code Definition
High-piled Storage Area — IFC 2009 definition: An area within a building which is designated, intended, proposed or actually used for high-piled combustible …
- High-rise Building: Building Code Definition
High-rise Building — IBC 2009 definition: A building with an occupied floor located more than 75 feet (22 860 mm) above the …
- Highway: Building Code Definition
Highway — IFC 2009 definition: A public street, public alley or public road.
- Hill: Building Code Definition
Hill — IRC 2009 definition: With respect to topographic wind effects, a land surface characterized by strong relief in any horizontal …
- Historic Buildings: Building Code Definition
Historic Buildings — IBC 2009 definition: Buildings that are listed in or eligible for listing in the National Register of Historic Places …