Building Code Glossary
Wythe: Building Code Definition
How the IBC 2009 define wythe, 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
Wythe is a defined term in the International Building Code (IBC) 2009, in Masonry. The code's own words are: “Each continuous, vertical section of a wall, one masonry unit in thickness.” 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 6 chapters of this corpus, most often in Wall Construction (IRC 2009), Fire and Smoke Protection Features (IBC 2009), Masonry (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?
Wythe — IBC 2009, Masonry:
Each continuous, vertical section of a wall, one masonry unit in thickness.
What must be verified before using this guidance?
Wythe is defined once in this corpus, in the Masonry chapter of the International Building Code (IBC) 2009:
Each continuous, vertical section of a wall, one masonry unit in thickness.
Where wythe is used in the code
The term appears in 6 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Wall Construction | IRC 2009 | 64 |
| Fire and Smoke Protection Features | IBC 2009 | 40 |
| Masonry | IBC 2009 | 19 |
| Wall Covering | IRC 2009 | 8 |
| Chimneys and Fireplaces | IRC 2009 | 7 |
| Definitions | IBC 2009 | 3 |
The term in use
How the code actually writes about wythe, quoted from the 2009 text hosted here:
Each masonry wythe shall be supported by at least two-thirds of the wythe thickness.
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.
Flashing and weep holes shall be located in the masonry veneer wythe in accordance with Figure R703.7.2.1.
The terms wythe 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 wythe covers:
- Masonry Unit — IBC 2009: Brick, tile, stone, glass block or concrete block conforming to the requirements specified in Section 2103.
- 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.
Wythe: 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 | Wall Construction (IRC 2009) | |
| Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 2009) | |
| Re-check the requirement that uses it | Masonry (IBC 2009) | |
| Re-check the requirement that uses it | Wall Covering (IRC 2009) | |
| Confirm the dependent definition | Masonry Unit | |
| Confirm the dependent definition | Masonry | |
| 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
- Masonry Unit: 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 wythe?
The International Building Code (IBC) 2009 defines it in Masonry as: “Each continuous, vertical section of a wall, one masonry unit in thickness.” 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 wythe?
In this corpus the term is used across 6 chapters, led by Wall Construction in the IRC 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 wythe in construction definition?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Masonry: “Each continuous, vertical section of a wall, one masonry unit in thickness.” 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.
What does IBC mean in building codes?
Building is a separate defined term. The IBC 2009 defines it as: “Any structure used or intended for supporting or sheltering any use or occupancy.” That is not the same as wythe, which the IBC 2009 defines as “Each continuous, vertical section of a wall, one masonry unit in thickness.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
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