Building Code Glossary
Developed Length: Building Code Definition
How the IRC 2009, IPC 2009 define developed length, 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
Developed length is a defined term in the International Residential Code (IRC) 2009, in Definitions. The code's own words are: “The length of a pipeline measured along the center line of the pipe and fittings.” The IPC 2009 words it differently, in Definitions: “The length of a pipeline measured along the centerline of the pipe and fittings.” The IPC 2009 defines the same term with different wording, so the controlling text depends on which code governs the question in front of you — the comparison below sets the versions side by side. The term is used in 11 chapters of this corpus, most often in Vents (IPC 2009), Vents (IRC 2009), Sanitary Drainage (IRC 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?
Developed Length — IRC 2009, Definitions:
The length of a pipeline measured along the center line of the pipe and fittings.
What must be verified before using this guidance?
Two of the I-Codes in this corpus define Developed Length, and the wording is not identical — read the version that governs your question.
| Code | Where it is defined | Definition |
|---|---|---|
| IRC 2009 | Definitions | The length of a pipeline measured along the center line of the pipe and fittings. |
| IPC 2009 | Definitions | The length of a pipeline measured along the centerline of the pipe and fittings. |
Where developed length is used in the code
The term appears in 11 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.
| Chapter | Code | Mentions |
|---|---|---|
| Vents | IPC 2009 | 18 |
| Vents | IRC 2009 | 8 |
| Sanitary Drainage | IRC 2009 | 7 |
| Sanitary Drainage | IPC 2009 | 6 |
| Water Supply and Distribution | IRC 2009 | 6 |
| Definitions | IPC 2009 | 4 |
| Definitions | IRC 2009 | 4 |
| Indirect/special Waste | IPC 2009 | 2 |
| Tanks | IPC 2009 | 2 |
| Traps, Interceptors and Separators | IPC 2009 | 2 |
| Water Supply and Distribution | IPC 2009 | 1 |
The term in use
How the code actually writes about developed length, quoted from the 2009 text hosted here:
The number of fixture units shall be the sum of all fixture units on all stacks connected thereto, and the developed length shall be the longest vent length from the intersection at the base of the most distant stack to the vent terminal in the open air, as a direct extension of one stack.
The maximum developed length of wet-vented fixture drains shall comply with Table P31 05.1.
Where more than one change of direction occurs in a run of piping, only one cleanout shall be required in each 40 feet (12 192 mm) of developed length of the drainage piping.
Developed Length: 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 | |
| Read the definition in the adopted IPC | Definitions | |
| Re-check the requirement that uses it | Vents (IPC 2009) | |
| Re-check the requirement that uses it | Vents (IRC 2009) | |
| Re-check the requirement that uses it | Sanitary Drainage (IRC 2009) | |
| Re-check the requirement that uses it | Sanitary Drainage (IPC 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
- 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 developed length?
The International Residential Code (IRC) 2009 defines it in Definitions as: “The length of a pipeline measured along the center line of the pipe and fittings.” 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 developed length?
In this corpus the term is used across 11 chapters, led by Vents in the IPC 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 does "developed length" mean?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “The length of a pipeline measured along the center line of the pipe and fittings.” It is defined in IRC 2009, IPC 2009. Because it is a defined term, whatever the adopted edition says it means is what every section using it means — so check Chapter 2 of that edition and any local amendment before relying on this wording.
What does "developed length" mean in the context of plumbing?
In the 2009 I-Codes hosted here it is a defined term rather than a description. The IRC 2009 states, in Definitions: “The length of a pipeline measured along the center line of the pipe and fittings.” It is defined in IRC 2009, IPC 2009. It is not the same as Plumbing, which the IRC 2009 defines separately as “For the purpose of this code, plumbing refers to those installations, repairs, maintenance and alterations regulated by Chapters 25 through 33.” Because it is a defined term, whatever the adopted edition says it means is what every section using it means — so check Chapter 2 of that edition and any local amendment before relying on this wording.
What does IRC mean in building code?
Building is a separate defined term. The IBC 2009 defines it as: “Any structure used or intended for supporting or sheltering any use or occupancy.” That is not the same as developed length, which the IRC 2009 defines as “The length of a pipeline measured along the center line of the pipe and fittings.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.
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