Building Code Glossary
Autoclaved Aerated Concrete (AAC): Building Code Definition
How the IBC 2009 define autoclaved aerated concrete (aac), 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
Autoclaved aerated concrete (aac) is a defined term in the International Building Code (IBC) 2009, in Masonry. The code's own words are: “Low-density cementitious product of calcium silicate hydrates, whose material specifications are defined in ASTM C 1386.” 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 3 chapters of this corpus, most often in Masonry (IBC 2009), Structural Design (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. 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?
Autoclaved Aerated Concrete (AAC) — IBC 2009, Masonry:
Low-density cementitious product of calcium silicate hydrates, whose material specifications are defined in ASTM C 1386.
What must be verified before using this guidance?
Autoclaved Aerated Concrete (AAC) is defined once in this corpus, in the Masonry chapter of the International Building Code (IBC) 2009:
Low-density cementitious product of calcium silicate hydrates, whose material specifications are defined in ASTM C 1386.
Where autoclaved aerated concrete (aac) is used in the code
The term appears in 3 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Masonry | IBC 2009 | 4 |
| Structural Design | IBC 2009 | 2 |
| Definitions | IBC 2009 | 1 |
Autoclaved Aerated Concrete (AAC): 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 | Masonry | |
| Re-check the requirement that uses it | Masonry (IBC 2009) | |
| Re-check the requirement that uses it | Structural Design (IBC 2009) | |
| Re-check the requirement that uses it | Definitions (IBC 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
- Chimney: Building Code Definition
- Tile: Building Code Definition
- Fireplace: Building Code Definition
- Masonry: 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 autoclaved aerated concrete (aac)?
The International Building Code (IBC) 2009 defines it in Masonry as: “Low-density cementitious product of calcium silicate hydrates, whose material specifications are defined in ASTM C 1386.” 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 autoclaved aerated concrete (aac)?
In this corpus the term is used across 3 chapters, led by Masonry 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 AAC masonry?
AAC Masonry is a separate defined term. The IBC 2009 defines it as: “Masonry made of autoclaved aerated concrete (AAC) units, manufactured without internal reinforcement and bonded together using thin- or thick-bed mortar.” That is not the same as autoclaved aerated concrete (aac), which the IBC 2009 defines as “Low-density cementitious product of calcium silicate hydrates, whose material specifications are defined in ASTM C 1386.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
Related pages
- Attic, Habitable: Building Code Definition
Attic, Habitable — IRC 2009 definition: A finished or unfinished area, not considered a story, complying with all ofthe following requirements:
- Attic: Building Code Definition
Attic — IBC 2009 definition: The space between the ceiling beams of the top story and the roof rafters.
- Audible Alarm Notification Appliance: Building Code Definition
Audible Alarm Notification Appliance — IBC 2009 definition: A notification appliance that alerts by the sense of hearing.
- Automatic Fire-extinguishing System: Building Code Definition
Automatic Fire-extinguishing System — IBC 2009 definition: An approved system of devices and equipment which automatically detects a fire and discharges an approvedfire-ext…
- Automatic Smoke Detection System: Building Code Definition
Automatic Smoke Detection System — IBC 2009 definition: A fire alarm system that has initiation devices that utilize smoke detectors for protection of an …
- Automatic Sprinkler System: Building Code Definition
Automatic Sprinkler System — IBC 2009 definition: An automatic sprinkler system, for fire protection purposes, is an integrated system of underground and overhead …