# Wood/plastic Composite: Building Code Definition > How the IRC 2009 define wood/plastic composite, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/wood-plastic-composite/ - 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 | IRC 2009 (2009 editions transcribed in this corpus) | | Primary source | IRC 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 Wood/plastic composite is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “A composite material made primarily from wood or cellulose-based materials and plastic.” No other I-Code in this corpus defines it, so the IRC 2009 definition is the one to work from. The term is used in 3 chapters of this corpus, most often in Building Planning (IRC 2009), Floors (IRC 2009), Definitions (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? **Wood/plastic Composite** — IRC 2009, Definitions: > A composite material made primarily from wood or cellulose-based materials and plastic. ![Labeled code-term definition diagram: Wood/plastic Composite: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/wood-plastic-composite/diagram-1344.webp) *How the IRC 2009 define wood/plastic composite, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? **Wood/plastic Composite** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) chapter of the International Residential Code (IRC) 2009: > A composite material made primarily from wood or cellulose-based materials and plastic. ## Where wood/plastic composite 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 | | --- | --- | --- | | [Building Planning](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/building-planning.md) | IRC 2009 | 16 | | [Floors](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/floors.md) | IRC 2009 | 10 | | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/definitions.md) | IRC 2009 | 1 | ### The term in use How the code actually writes about wood/plastic composite, quoted from the 2009 text hosted here: > Wood/plastic composite stair treads shall comply with the provisions of Section R31 7.4. — [IRC 2009 §R311.7.4.4](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/building-planning.md) > Wood/plastic composite deck boards shall be installed in accordance with the manufacturer's instructions. — [IRC 2009 §R502.2.2.4](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/floors.md) ## Wood/plastic Composite: 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 IRC | Definitions | | | Re-check the requirement that uses it | Building Planning (IRC 2009) | | | Re-check the requirement that uses it | Floors (IRC 2009) | | | Re-check the requirement that uses it | Definitions (IRC 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](https://harth.build/resources/glossary.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) - [Dwelling Unit: Building Code Definition](https://harth.build/resources/glossary/dwelling-unit.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 wood/plastic composite? The International Residential Code (IRC) 2009 defines it in Definitions as: “A composite material made primarily from wood or cellulose-based materials and plastic.” 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 wood/plastic composite? In this corpus the term is used across 3 chapters, led by Building Planning 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. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fwood-plastic-composite%2F - View this page in a browser: https://harth.build/resources/glossary/wood-plastic-composite/ - All resources for agents: https://harth.build/llms.txt