Building Code Glossary
Conditioned Area: Building Code Definition
How the IRC 2009 define conditioned area, where the wording differs, and which chapters depend on the term.
On this page
Last updated September 7, 2026 · 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.
Direct answer
Conditioned area is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “That area within a building provided with heating and/or cooling systems or appliances capable of maintaining, through design or heat loss/gain, 68°F (20°C) during the heating season and/or 80°F (27°C) during the cooling season, or has a fixed opening directly adjacent to a conditioned area.” 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 Fuel Gas (IRC 2009), Definitions (IRC 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, Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.
What does this term mean?
Conditioned Area — IRC 2009, Definitions:
That area within a building provided with heating and/or cooling systems or appliances capable of maintaining, through design or heat loss/gain, 68°F (20°C) during the heating season and/or 80°F (27°C) during the cooling season, or has a fixed opening directly adjacent to a conditioned area.
What must be verified before using this guidance?
Conditioned Area is defined once in this corpus, in the Definitions chapter of the International Residential Code (IRC) 2009:
That area within a building provided with heating and/or cooling systems or appliances capable of maintaining, through design or heat loss/gain, 68°F (20°C) during the heating season and/or 80°F (27°C) during the cooling season, or has a fixed opening directly adjacent to a conditioned area.
Where conditioned area 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 |
|---|---|---|
| Fuel Gas | IRC 2009 | 3 |
| Definitions | IRC 2009 | 2 |
| Definitions | IMC 2009 | 1 |
Conditioned Area compared with Conditioned Space
These two are the closest pair in the 2009 I-Codes: about 48 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 | |
|---|---|
| Conditioned Area (IRC 2009) | appliances, 68, 20, 80, 27, fixed, opening, adjacent |
| Conditioned Space (IRC 2009) | energy, purposes, space, equipmentor, 50, io, 85, 29, communicates, mechanical, room, being |
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 conditioned area and conditioned space.
The terms conditioned area 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 conditioned area covers:
- Building — IBC 2009: Any structure used or intended for supporting or sheltering any use or occupancy.
Conditioned Area: what to open, and in what order
Every row is a document this term depends on. The ICC code library and the ICC adoption maps cover the middle rows.
| Check | Where | Confirmed |
|---|---|---|
| Read the definition in the adopted IRC | Definitions | |
| Re-check the requirement that uses it | Fuel Gas (IRC 2009) | |
| Re-check the requirement that uses it | Definitions (IRC 2009) | |
| Re-check the requirement that uses it | Definitions (IMC 2009) | |
| Confirm the dependent definition | Building | |
| 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
- Building: Building Code Definition
- Construction Documents: Building Code Definition
- Registered Design Professional: Building Code Definition
- Dwelling Unit: Building Code Definition
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 publishes the current model text and the ICC adoption maps show which edition a jurisdiction has adopted; those sources control.
Source links
Frequently asked questions
What is the code definition of conditioned area?
The International Residential Code (IRC) 2009 defines it in Definitions as: “That area within a building provided with heating and/or cooling systems or appliances capable of maintaining, through design or heat loss/gain, 68°F (20°C) during the heating season and/or 80°F (27°C) during the cooling season, or has a fixed opening directly adjacent to a conditioned area.” 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 conditioned area?
In this corpus the term is used across 3 chapters, led by Fuel Gas 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 is considered conditioned space in a building?
Conditioned Space is a separate defined term. The IRC 2009 defines it as: “For energy purposes, space within a building that is provided with heating and/or cooling equipmentor systems capable of maintaining, through design or heat loss/gain, 50°F (IO°C) during the heating season and 85°F (29°C) during the cooling season, or communicates directly with a conditioned space. For …” That is not the same as conditioned area, which the IRC 2009 defines as “That area within a building provided with heating and/or cooling systems or appliances capable of maintaining, through design or heat loss/gain, 68°F (20°C) during the heating season and/or 80°F (27°C) during the cooling season, or has a fixed opening directly …” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
What does "conditioned floor area" mean?
Conditioned Floor Area is a separate defined term. The IRC 2009 defines it as: “The horizontal projection of the floors associated with the conditioned space.” That is not the same as conditioned area, which the IRC 2009 defines as “That area within a building provided with heating and/or cooling systems or appliances capable of maintaining, through design or heat loss/gain, 68°F (20°C) during the heating season and/or 80°F (27°C) during the cooling season, or has a fixed opening directly …” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
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