# Heated Slab: Building Code Definition > How the IECC 2009 define heated slab, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/heated-slab/ - 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 | 5 (counted across the codes hosted here) | | Wording identical across codes | Single code (compare before citing one code's wording under another) | ## Direct answer Heated slab is a defined term in the International Energy Conservation Code (IECC) 2009, in Definitions. The code's own words are: “Slab-on-grade construction in which the heating elements, hydronic tubing, or hot air distribution system is in contact with, or placed within or under, the slab.” 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 5 chapters of this corpus, most often in Foundations (IRC 2009), Commercial Energy Efficiency (IECC 2009), Hydronic Piping (IMC 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? **Heated Slab** — IECC 2009, Definitions: > Slab-on-grade construction in which the heating elements, hydronic tubing, or hot air distribution system is in contact with, or placed within or under, the slab. ![Labeled code-term definition diagram: Heated Slab: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/heated-slab/diagram-1344.webp) *How the IECC 2009 define heated slab, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? **Heated Slab** 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: > Slab-on-grade construction in which the heating elements, hydronic tubing, or hot air distribution system is in contact with, or placed within or under, the slab. ## Where heated slab is used in the code The term appears in 5 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next. | Chapter | Code | Mentions | | --- | --- | --- | | [Foundations](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/foundations.md) | IRC 2009 | 4 | | [Commercial Energy Efficiency](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md) | IECC 2009 | 2 | | [Hydronic Piping](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/hydronic-piping.md) | IMC 2009 | 2 | | [Hvdronic Piping](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/hvdronic-piping.md) | IRC 2009 | 2 | | [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 heated slab, quoted from the 2009 text hosted here: > The minimum thermal resistance (R-value) of the insulation around the perimeter of unheated or heated slab-on-grade floors shall be as specified in Table 502.2 (1). — [IECC 2009 §502.2.6](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md) > A thermal break shall be provided consisting of asphalt expansion joint materials or similar insulating materials at a point where a heated slab meets a foundation wall or other conductive slab. — [IMC 2009 §1209.5.3](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/hydronic-piping.md) > A thermal break consisting of asphalt expansionjoint materials or similar insulating materials shall be provided at a point where a heated slab meets a foundation wall or other conductive slab. — [IRC 2009 §M2103.2.3](https://harth.build/resources/building-codes/us-states/maryland/irc-2009/hvdronic-piping.md) ## The terms heated slab is built out of The definition above leans on 3 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what heated slab covers: - **[Air Distribution System](https://harth.build/resources/glossary/air-distribution-system.md)** — IMC 2009: Any system of ducts, plenums and air-handling equipment that circulates air within a space or spaces and includes systems made up of one or more air-handling units. - **[System](https://harth.build/resources/glossary/system.md)** — IFC 2009: An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping. - **[Grade](https://harth.build/resources/glossary/grade.md)** — IRC 2009: The finished ground level adjoining the building at all exterior walls. ## Heated Slab: 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 | Foundations (IRC 2009) | | | Re-check the requirement that uses it | Commercial Energy Efficiency (IECC 2009) | | | Re-check the requirement that uses it | Hydronic Piping (IMC 2009) | | | Re-check the requirement that uses it | Hvdronic Piping (IRC 2009) | | | Confirm the dependent definition | Air Distribution System | | | Confirm the dependent definition | System | | | 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) - [Air Distribution System: Building Code Definition](https://harth.build/resources/glossary/air-distribution-system.md) - [System: Building Code Definition](https://harth.build/resources/glossary/system.md) - [Grade: Building Code Definition](https://harth.build/resources/glossary/grade.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 heated slab? The International Energy Conservation Code (IECC) 2009 defines it in Definitions as: “Slab-on-grade construction in which the heating elements, hydronic tubing, or hot air distribution system is in contact with, or placed within or under, the slab.” 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 heated slab? In this corpus the term is used across 5 chapters, led by Foundations 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 are the requirements for slab on grade insulation? Grade is a separate defined term. The IRC 2009 defines it as: “The finished ground level adjoining the building at all exterior walls.” That is not the same as heated slab, which the IECC 2009 defines as “Slab-on-grade construction in which the heating elements, hydronic tubing, or hot air distribution system is in contact with, or placed within or under, the slab.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fheated-slab%2F - View this page in a browser: https://harth.build/resources/glossary/heated-slab/ - All resources for agents: https://harth.build/llms.txt