Building Code Glossary
Collar Joint: Building Code Definition
How the IBC 2009 define collar joint, 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
Collar joint is a defined term in the International Building Code (IBC) 2009, in Masonry. The code's own words are: “Verticallongitudinaljoint between wythes of masonry or between masonry and backup construction that is permitted to be filled with mortar or grout.” 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), Wall Construction (IRC 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?
Collar Joint — IBC 2009, Masonry:
Verticallongitudinaljoint between wythes of masonry or between masonry and backup construction that is permitted to be filled with mortar or grout.
What must be verified before using this guidance?
Collar Joint is defined once in this corpus, in the Masonry chapter of the International Building Code (IBC) 2009:
Verticallongitudinaljoint between wythes of masonry or between masonry and backup construction that is permitted to be filled with mortar or grout.
Where collar joint 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 | 5 |
| Wall Construction | IRC 2009 | 2 |
| Definitions | IBC 2009 | 1 |
The term in use
How the code actually writes about collar joint, quoted from the 2009 text hosted here:
Compressive strength of masonry shall be considered satisfactory if the compressive strength of each masonry wythe and grouted collar joint equals or exceeds the value of I'm for clay and concrete masonry and I'AAC for AAC masonry.
The terms collar joint is built out of
The definition above leans on 2 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what collar joint covers:
- Masonry — IBC 2009: A built-up construction or combination of building units or materials of clay, shale, concrete, glass, gypsum, stone or other approved units bonded together with or without mortar or grout or other accepted methods of joining.
- Mortar — IBC 2009: A plastic mixture of approved cementitious materials, fine aggregates and water used to bond masonry or other structural units.
Collar Joint: 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 | Wall Construction (IRC 2009) | |
| Re-check the requirement that uses it | Definitions (IBC 2009) | |
| Confirm the dependent definition | Masonry | |
| Confirm the dependent definition | Mortar | |
| 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?
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 collar joint?
The International Building Code (IBC) 2009 defines it in Masonry as: “Verticallongitudinaljoint between wythes of masonry or between masonry and backup construction that is permitted to be filled with mortar or grout.” 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 collar joint?
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 a collar joint in masonry construction?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Masonry: “Verticallongitudinaljoint between wythes of masonry or between masonry and backup construction that is permitted to be filled with mortar or grout.” It is defined in IBC 2009. It is not the same as Masonry, which the IBC 2009 defines separately as “A built-up construction or combination of building units or materials of clay, shale, concrete, glass, gypsum, stone or other approved units bonded together with or without mortar or grout or other accepted methods of joining.” 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.
What is considered a structure in building code?
Structure is a separate defined term. The IPC 2009 defines it as: “That which is built or constructed or a portion thereof.” That is not the same as collar joint, which the IBC 2009 defines as “Verticallongitudinaljoint between wythes of masonry or between masonry and backup construction that is permitted to be filled with mortar or grout.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
What is a collar joint in a pipe?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Masonry: “Verticallongitudinaljoint between wythes of masonry or between masonry and backup construction that is permitted to be filled with mortar or grout.” 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.
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