# Crawl Space Wall: Building Code Definition > How the IECC 2009 define crawl space wall, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/crawl-space-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 | 3 (counted across the codes hosted here) | | Wording identical across codes | Single code (compare before citing one code's wording under another) | ## Direct answer Crawl space wall is a defined term in the International Energy Conservation Code (IECC) 2009, in Definitions. The code's own words are: “The opaque portion of a wall that encloses a crawl space and is partially or totally below grade.” 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 3 chapters of this corpus, most often in Energy Efficiency (IRC 2009), Residential Energy Efficiency (IECC 2009), Definitions (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? **Crawl Space Wall** — IECC 2009, Definitions: > The opaque portion of a wall that encloses a crawl space and is partially or totally below grade. ![Labeled code-term definition diagram: Crawl Space Wall: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/crawl-space-wall/diagram-1344.webp) *How the IECC 2009 define crawl space wall, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? **Crawl Space 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: > The opaque portion of a wall that encloses a crawl space and is partially or totally below grade. ## Where crawl space wall 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 | | --- | --- | --- | | [Energy Efficiency](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/energy-efficiency.md) | IRC 2009 | 8 | | [Residential Energy Efficiency](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/residential-energy-efficiency.md) | IECC 2009 | 6 | | [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 crawl space wall, quoted from the 2009 text hosted here: > Crawl space wall insulation shall be permanently fastened to the wall and extend downward from the floor to the finished grade level and then vertically and/or horizontally for at least an additional 24 inches (610 mm). — [IECC 2009 §402.2.9](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/residential-energy-efficiency.md) ## Crawl Space Wall compared with Basement Wall These two are the closest pair in the 2009 I-Codes: about 45 per cent of their defining words are the same. The code states both and compares neither, so the difference is worth naming. | | Wording unique to it | | --- | --- | | **Crawl Space Wall** (IECC 2009) | crawl, space, partially, totally | | [Basement Wall](https://harth.build/resources/glossary/basement-wall.md) (IRC 2009) | one, side, basement, average, area, 50, percent, more, total, non, enclosing | Everything else in the two definitions is shared. If a project turns on which of the two applies, those words are the whole of the test — and a local amendment that edits one of them without editing the other moves the boundary between crawl space wall and basement wall. ## The terms crawl space 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 crawl space wall covers: - **[Grade](https://harth.build/resources/glossary/grade.md)** — IRC 2009: The finished ground level adjoining the building at all exterior walls. ## Crawl Space 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 | Energy Efficiency (IRC 2009) | | | Re-check the requirement that uses it | Residential Energy Efficiency (IECC 2009) | | | Re-check the requirement that uses it | Definitions (IECC 2009) | | | Confirm the dependent definition | Grade | | | 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) - [Grade: Building Code Definition](https://harth.build/resources/glossary/grade.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 crawl space wall? The International Energy Conservation Code (IECC) 2009 defines it in Definitions as: “The opaque portion of a wall that encloses a crawl space and is partially or totally below grade.” 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 crawl space wall? In this corpus the term is used across 3 chapters, led by Energy Efficiency 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%2Fcrawl-space-wall%2F - View this page in a browser: https://harth.build/resources/glossary/crawl-space-wall/ - All resources for agents: https://harth.build/llms.txt