# Building Trap: Building Code Definition > How the IPC 2009 define building trap, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/building-trap/ - 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 | IPC 2009 (2009 editions transcribed in this corpus) | | Primary source | IPC 2009 Definitions (model text, not a jurisdiction's adopted text) | | Chapters using the term | 3 (counted across the codes hosted here) | | Wording identical across codes | Single code (compare before citing one code's wording under another) | ## Direct answer Building trap is a defined term in the International Plumbing Code (IPC) 2009, in Definitions. The code's own words are: “A device, fitting or assembly of fittings installed in the building drain to prevent circulation of air between the drainage system of the building and the building sewer.” No other I-Code in this corpus defines it, so the IPC 2009 definition is the one to work from. The term is used in 3 chapters of this corpus, most often in Definitions (IPC 2009), Traps, Interceptors and Separators (IPC 2009), Traps (IRC 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? **Building Trap** — IPC 2009, Definitions: > A device, fitting or assembly of fittings installed in the building drain to prevent circulation of air between the drainage system of the building and the building sewer. ![Labeled code-term definition diagram: Building Trap: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/building-trap/diagram-1344.webp) *How the IPC 2009 define building trap, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? **Building Trap** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) chapter of the International Plumbing Code (IPC) 2009: > A device, fitting or assembly of fittings installed in the building drain to prevent circulation of air between the drainage system of the building and the building sewer. ## Where building trap 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 | | --- | --- | --- | | [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/definitions.md) | IPC 2009 | 2 | | [Traps, Interceptors and Separators](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/traps-interceptors-and-separators.md) | IPC 2009 | 2 | | [Traps](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/traps.md) | IRC 2009 | 2 | ## The terms building trap is built out of The definition above leans on 5 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what building trap covers: - **[Drainage System](https://harth.build/resources/glossary/drainage-system.md)** — IPC 2009: Piping within a public or private premise that conveys sewage, rainwater or other liquid wastes to a point of disposal. - **[Building Drain](https://harth.build/resources/glossary/building-drain.md)** — IRC 2009: The lowest piping that collects the discharge from all other drainage piping inside the house and extends 30 inches (762 mm) in developed length of pipe, beyond the exterior walls and conveys the drainage to the building sewer. - **[Building Sewer](https://harth.build/resources/glossary/building-sewer.md)** — IRC 2009: That part of the drainage system that extends from the end of the building drain and conveys its discharge to a public sewer, private sewer, individual sewage-diSposal system or other point of disposal. - **[Building](https://harth.build/resources/glossary/building.md)** — IBC 2009: Any structure used or intended for supporting or sheltering any use or occupancy. - **[Fitting](https://harth.build/resources/glossary/fitting.md)** — IRC 2009: An accessory such as a locknut, bushing or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function. ## Building Trap: 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 IPC | Definitions | | | Re-check the requirement that uses it | Definitions (IPC 2009) | | | Re-check the requirement that uses it | Traps, Interceptors and Separators (IPC 2009) | | | Re-check the requirement that uses it | Traps (IRC 2009) | | | Confirm the dependent definition | Drainage System | | | Confirm the dependent definition | Building Drain | | | Confirm the dependent definition | Building Sewer | | | 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) - [Drainage System: Building Code Definition](https://harth.build/resources/glossary/drainage-system.md) - [Building Sewer: Building Code Definition](https://harth.build/resources/glossary/building-sewer.md) - [Building Drain: Building Code Definition](https://harth.build/resources/glossary/building-drain.md) - [Building: Building Code Definition](https://harth.build/resources/glossary/building.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 building trap? The International Plumbing Code (IPC) 2009 defines it in Definitions as: “A device, fitting or assembly of fittings installed in the building drain to prevent circulation of air between the drainage system of the building and the building sewer.” 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 building trap? In this corpus the term is used across 3 chapters, led by Definitions in the IPC 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. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fbuilding-trap%2F - View this page in a browser: https://harth.build/resources/glossary/building-trap/ - All resources for agents: https://harth.build/llms.txt