# Compensating Hoods: Building Code Definition > How the IMC 2009 define compensating hoods, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/compensating-hoods/ - 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 | IMC 2009 (2009 editions transcribed in this corpus) | | Primary source | IMC 2009 Definitions (model text, not a jurisdiction's adopted text) | | Chapters using the term | 2 (counted across the codes hosted here) | | Wording identical across codes | Single code (compare before citing one code's wording under another) | ## Direct answer Compensating hoods is a defined term in the International Mechanical Code (IMC) 2009, in Definitions. The code's own words are: “Compensating hoods are those having integral (built-in) makeup air supply. The makeup air supply for such hoods is generally supplied from: short-circuit flow from inside the hood, air curtain flow from the bottom of the front face, and front face discharge from the outside front wall of the hood. The compensating makeup airflow can also …” No other I-Code in this corpus defines it, so the IMC 2009 definition is the one to work from. The term is used in 2 chapters of this corpus, most often in Exhaust Systems (IMC 2009), Definitions (IMC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted. *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? **Compensating Hoods** — IMC 2009, Definitions: > Compensating hoods are those having integral (built-in) makeup air supply. The makeup air supply for such hoods is generally supplied from: short-circuit flow from inside the hood, air curtain flow from the bottom of the front face, and front face discharge from the outside front wall of the hood. The compensating makeup airflow can also be supplied from the rear or side ofthe hood, or the rear, front or sides ofthe cooking equipment. The makeup airflow can be one or a combination of methods. ![Labeled code-term definition diagram: Compensating Hoods: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/compensating-hoods/diagram-1344.webp) *How the IMC 2009 define compensating hoods, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? **Compensating Hoods** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/definitions.md) chapter of the International Mechanical Code (IMC) 2009: > Compensating hoods are those having integral (built-in) makeup air supply. The makeup air supply for such hoods is generally supplied from: short-circuit flow from inside the hood, air curtain flow from the bottom of the front face, and front face discharge from the outside front wall of the hood. The compensating makeup airflow can also be supplied from the rear or side ofthe hood, or the rear, front or sides ofthe cooking equipment. The makeup airflow can be one or a combination of methods. ## Where compensating hoods is used in the code The term appears in 2 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next. | Chapter | Code | Mentions | | --- | --- | --- | | [Exhaust Systems](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/exhaust-systems.md) | IMC 2009 | 4 | | [Definitions](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/definitions.md) | IMC 2009 | 2 | ### The term in use How the code actually writes about compensating hoods, quoted from the 2009 text hosted here: > Manufacturers of compensating hoods shall provide a label indicating minimum exhaust flow and/or maximum makeup airflow that provides capture and containment of the exhaust effluent. — [IMC 2009 §508.2](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/exhaust-systems.md) ## The terms compensating hoods 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 compensating hoods covers: - **[Equipment](https://harth.build/resources/glossary/equipment.md)** — IRC 2009: All piping, ducts, vents, control devices and other components of systems other than appliances that are permanently installed and integrated to provide control of environmental conditions for buildings. ## Compensating Hoods: 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 IMC | Definitions | | | Re-check the requirement that uses it | Exhaust Systems (IMC 2009) | | | Re-check the requirement that uses it | Definitions (IMC 2009) | | | Confirm the dependent definition | Equipment | | | 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) - [Equipment: Building Code Definition](https://harth.build/resources/glossary/equipment.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 compensating hoods? The International Mechanical Code (IMC) 2009 defines it in Definitions as: “Compensating hoods are those having integral (built-in) makeup air supply. The makeup air supply for such hoods is generally supplied from: short-circuit flow from inside the hood, air curtain flow from the bottom of the front face, and front face discharge from the outside front wall of the hood. The compensating makeup airflow can also be supplied from the rear or side ofthe hood, or the rear, front or sides ofthe cooking equipment. The makeup airflow can be one or a combination of methods.” 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 compensating hoods? In this corpus the term is used across 2 chapters, led by Exhaust Systems in the IMC 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 the NFPa code for kitchen hoods? Kitchen is a separate defined term. The IRC 2009 defines it as: “Kitchen shall mean an area used, or designated to be used, for the preparation of food.” That is not the same as compensating hoods, which the IMC 2009 defines as “Compensating hoods are those having integral (built-in) makeup air supply. The makeup air supply for such hoods is generally supplied from: short-circuit flow from inside the hood, air curtain flow from the bottom of the front face, and front face …” — 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%2Fcompensating-hoods%2F - View this page in a browser: https://harth.build/resources/glossary/compensating-hoods/ - All resources for agents: https://harth.build/llms.txt