# Curtain Wall: Building Code Definition > How the IECC 2009 define curtain wall, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/curtain-wall/ - Last updated: 2026-09-07 - Data source: 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. ## Key facts | Fact | Value | | --- | --- | | Defined in | IECC 2009 (2009 editions transcribed in this corpus) | | Primary source | IECC 2009 Definitions (model text, not a jurisdiction's adopted text) | | Chapters using the term | 8 (counted across the codes hosted here) | | Wording identical across codes | Single code (compare before citing one code's wording under another) | ## Direct answer Curtain wall is a defined term in the International Energy Conservation Code (IECC) 2009, in Definitions. The code's own words are: “Fenestration products used to create an external nonload-bearing wall that is designed to separate the exterior and interior environments.” No other I-Code in this corpus defines it, so the IECC 2009 definition is the one to work from. The term is used in 8 chapters of this corpus, most often in Fire and Smoke Protection Features (IBC 2009), Foundations (IRC 2009), Commercial Energy Efficiency (IECC 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](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.* ## What does this term mean? **Curtain Wall** — IECC 2009, Definitions: > Fenestration products used to create an external nonload-bearing wall that is designed to separate the exterior and interior environments. ![Labeled code-term definition diagram: Curtain Wall: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/curtain-wall/diagram-1344.webp) *How the IECC 2009 define curtain wall, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? **Curtain Wall** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/definitions.md) chapter of the International Energy Conservation Code (IECC) 2009: > Fenestration products used to create an external nonload-bearing wall that is designed to separate the exterior and interior environments. ## Where curtain wall is used in the code The term appears in 8 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](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md) | IBC 2009 | 13 | | [Foundations](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/foundations.md) | IRC 2009 | 7 | | [Commercial Energy Efficiency](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md) | IECC 2009 | 6 | | [Building Planning](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/building-planning.md) | IRC 2009 | 4 | | [Glass and Glazing](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/glass-and-glazing.md) | IBC 2009 | 3 | | [Soils and Foundations](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/soils-and-foundations.md) | IBC 2009 | 2 | | [Wood](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/wood.md) | IBC 2009 | 1 | | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/definitions.md) | IECC 2009 | 1 | ### The term in use How the code actually writes about curtain wall, quoted from the 2009 text hosted here: > The void created at the intersection of a floor/ceiling assembly and an exterior curtain wall assembly shall be protected in accordance with Section 714.4. — [IBC 2009 §705.9.1](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-and-smoke-protection-features.md) > Curtain wall, storefront glazing and commercial-glazed swinging entrance doors and revolving doors shall be tested for air leakage at 1.57 pounds per square foot (psf) (75 Pa) in accordance with ASTM E 283. — [IECC 2009 §502.4.2](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md) ## The terms curtain wall 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 curtain wall covers: - **[Fenestration](https://harth.build/resources/glossary/fenestration.md)** — IRC 2009: Skylights, roof windows, vertical windows (whether fixed or moveable); opaque doors; glazed doors; glass block; and combination opaque/glazed doors. ## Curtain Wall: what to open, and in what order Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) cover the middle rows. | Check | Where | Confirmed | | --- | --- | --- | | Read the definition in the adopted IECC | Definitions | | | Re-check the requirement that uses it | Fire and Smoke Protection Features (IBC 2009) | | | Re-check the requirement that uses it | Foundations (IRC 2009) | | | Re-check the requirement that uses it | Commercial Energy Efficiency (IECC 2009) | | | Re-check the requirement that uses it | Building Planning (IRC 2009) | | | Confirm the dependent definition | Fenestration | | | 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](https://harth.build/resources/glossary.md) - [Fenestration: Building Code Definition](https://harth.build/resources/glossary/fenestration.md) - [Building: Building Code Definition](https://harth.build/resources/glossary/building.md) - [Construction Documents: Building Code Definition](https://harth.build/resources/glossary/construction-documents.md) - [Registered Design Professional: Building Code Definition](https://harth.build/resources/glossary/registered-design-professional.md) ## 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](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. ### Source links - [codes.iccsafe.org](https://codes.iccsafe.org/codes) - [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/) ## Frequently asked questions ### What is the code definition of curtain wall? The International Energy Conservation Code (IECC) 2009 defines it in Definitions as: “Fenestration products used to create an external nonload-bearing wall that is designed to separate the exterior and interior environments.” 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 curtain wall? In this corpus the term is used across 8 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 considered a curtain wall? In the 2009 I-Codes hosted here it is a defined term rather than a description. The IECC 2009 states, in Definitions: “Fenestration products used to create an external nonload-bearing wall that is designed to separate the exterior and interior environments.” It is defined in IECC 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. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fcurtain-wall%2F - View this page in a browser: https://harth.build/resources/glossary/curtain-wall/ - All resources for agents: https://harth.build/llms.txt