Building Code Glossary
Concrete, Lightweight Aggregate: Building Code Definition
How the IBC 2009 define concrete, lightweight aggregate, 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
Concrete, lightweight aggregate is a defined term in the International Building Code (IBC) 2009, in Fire and Smoke Protection Features. The code's own words are: “Concrete made with aggregates of expanded clay, shale, slag or slate or sintered fly ash or any natural lightweight aggregate meeting ASTM C 330 and possessing equivalent fire-resistance properties and weighing 85 to 115 pcf (1360 to 1840 kg/m3).” No other I-Code in this corpus defines it, so the IBC 2009 definition is the one to work from. The term is used in 2 chapters of this corpus, most often in Fire and Smoke Protection Features (IBC 2009), Definitions (IBC 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?
Concrete, Lightweight Aggregate — IBC 2009, Fire and Smoke Protection Features:
Concrete made with aggregates of expanded clay, shale, slag or slate or sintered fly ash or any natural lightweight aggregate meeting ASTM C 330 and possessing equivalent fire-resistance properties and weighing 85 to 115 pcf (1360 to 1840 kg/m3).
What must be verified before using this guidance?
Concrete, Lightweight Aggregate is defined once in this corpus, in the Fire and Smoke Protection Features chapter of the International Building Code (IBC) 2009:
Concrete made with aggregates of expanded clay, shale, slag or slate or sintered fly ash or any natural lightweight aggregate meeting ASTM C 330 and possessing equivalent fire-resistance properties and weighing 85 to 115 pcf (1360 to 1840 kg/m3).
Where concrete, lightweight aggregate 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 |
|---|---|---|
| Fire and Smoke Protection Features | IBC 2009 | 2 |
| Definitions | IBC 2009 | 1 |
Concrete, Lightweight Aggregate compared with Concrete, Sand-lightweight
These two are the closest pair in the 2009 I-Codes: about 60 per cent of their defining words are the same. The code states both and compares neither, so the difference is worth naming.
| Wording unique to it | |
|---|---|
| Concrete, Lightweight Aggregate (IBC 2009) | aggregates, weighing, 85, 115, 1360, 1840 |
| Concrete, Sand-lightweight (IBC 2009) | combination, sand, unit, weight, generally, between, 105, 120, 1680, 1920 |
Everything else in the two definitions is shared. If a project turns on which of the two applies, those words are the whole of the test — and a local amendment that edits one of them without editing the other moves the boundary between concrete, lightweight aggregate and concrete, sand-lightweight.
The terms concrete, lightweight aggregate is built out of
The definition above leans on 1 other defined term. Each carries its own code definition, and a local amendment to any of them changes what concrete, lightweight aggregate covers:
- Aggregate — IBC 2009: In roofing, crushed stone, crushed slag or water-worn gravel used for surfacing for roof coverings.
Concrete, Lightweight Aggregate: 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 | Fire and Smoke Protection Features | |
| Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 2009) | |
| Re-check the requirement that uses it | Definitions (IBC 2009) | |
| Confirm the dependent definition | Aggregate | |
| 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
- Aggregate: Building Code Definition
- Shaft: Building Code Definition
- Damper: Building Code Definition
- Fire-resistance Rating: 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 concrete, lightweight aggregate?
The International Building Code (IBC) 2009 defines it in Fire and Smoke Protection Features as: “Concrete made with aggregates of expanded clay, shale, slag or slate or sintered fly ash or any natural lightweight aggregate meeting ASTM C 330 and possessing equivalent fire-resistance properties and weighing 85 to 115 pcf (1360 to 1840 kg/m3).” 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 concrete, lightweight aggregate?
In this corpus the term is used across 2 chapters, led by Fire and Smoke Protection Features in the IBC 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 lightweight aggregate concrete?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Fire and Smoke Protection Features: “Concrete made with aggregates of expanded clay, shale, slag or slate or sintered fly ash or any natural lightweight aggregate meeting ASTM C 330 and possessing equivalent fire-resistance properties and weighing 85 to 115 pcf (1360 to 1840 kg/m3).” It is defined in IBC 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
- Concealed Piping: Building Code Definition
Concealed Piping — IRC 2009 definition: Piping that is located in a concealed location (see “Concealed location”).
- Concealed: Building Code Definition
Concealed — IRC 2009 definition: Rendered inaccessible by the structure or finish of the building.
- Concrete, Cellular: Building Code Definition
Concrete, Cellular — IBC 2009 definition: A lightweight insulating concrete made by mixing a preformed foam with portland cement slurry and having …
- Concrete, Perlite: Building Code Definition
Concrete, Perlite — IBC 2009 definition: A lightweight insulating concrete having a dry unit weight of approximately 30 pcf (480 kg/m3) made …
- Concrete, Vermiculite: Building Code Definition
Concrete, Vermiculite — IBC 2009 definition: A lightweight insulating concrete made with vermiculite concrete aggregate which is laminated micaceous material produced by …
- Condensate: Building Code Definition
Condensate — IRC 2009 definition: The liquid that separates from a gas due to a reduction in temperature, e.g., water that …