Updated 2026-09-07

Building Code Glossary

Fiberboard: Building Code Definition

How the IBC 2009 define fiberboard, where the wording differs, and which chapters depend on the term.

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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.

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Direct answer

Fiberboard is a defined term in the International Building Code (IBC) 2009, in Wood. The code's own words are: “A fibrous, homogeneous panel made from lignocellulosic fibers (usually wood or cane) and having a density of less than 31 pounds per cubic foot (pcf) (497 kg/m3) but more than 10 pcf (160 kg/m3).” No other I-Code in this corpus defines it, so the IBC 2009 definition is the one to work from. The term is used in 12 chapters of this corpus, most often in Wood (IBC 2009), Wall Construction (IRC 2009), Fire and Smoke Protection Features (IBC 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?

Fiberboard — IBC 2009, Wood:

A fibrous, homogeneous panel made from lignocellulosic fibers (usually wood or cane) and having a density of less than 31 pounds per cubic foot (pcf) (497 kg/m3) but more than 10 pcf (160 kg/m3).

Labeled code-term definition diagram: Fiberboard: Building Code Definition — How the IBC 2009 define fiberboard, where the wording differs, and which chapters depend on the term.

What must be verified before using this guidance?

Fiberboard is defined once in this corpus, in the Wood chapter of the International Building Code (IBC) 2009:

A fibrous, homogeneous panel made from lignocellulosic fibers (usually wood or cane) and having a density of less than 31 pounds per cubic foot (pcf) (497 kg/m3) but more than 10 pcf (160 kg/m3).

Where fiberboard is used in the code

The term appears in 12 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next.

Chapter	Code	Mentions
Wood	IBC 2009	37
Wall Construction	IRC 2009	20
Fire and Smoke Protection Features	IBC 2009	6
Roof Assemblies and Rooftop Structures	IBC 2009	4
Structural Tests and Special Inspections	IBC 2009	4
Explosives and Fireworks	IFC 2009	3
Wall Covering	IRC 2009	3
Definitions	IBC 2009	2
High-piled Combustible Storage	IFC 2009	2
Devices and Luminaires	IRC 2009	2
Definitions	IFC 2009	1
Lumber Yards and Woodworking Facilities	IFC 2009	1

The term in use

How the code actually writes about fiberboard, quoted from the 2009 text hosted here:

wood structural panels, fiberboard sheathing (when used structurally);

— IBC 2009 §2303.1

Continuously sheathed braced wall lines using structural fiberboard sheathing shall comply with this section.

— IRC 2009 §R602.10.5

Draftstopping materials shall not be less than1/z-inch (12.7 mm) gypsum board, 3/s-inch (9.5 mm) wood structural panel, 3/s-inch (9.5 mm) particleboard, I-inch (2S-mm) nominal lumber, cement fiberboard, batts or blankets of mineral wool or glass fiber, or other approved materials adequately supported.

— IBC 2009 §717.3.1

The terms fiberboard 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 fiberboard covers:

Cubic Foot — IRC 2009: The amount of gas that occupies 1 cubic foot (0.02832 m3) when at a temperature of 60°F (16°C), saturated with water vapor and under a pressure equivalent to that of 30 inches of mercury (101 kPa).

Fiberboard: 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 IBC	Wood
Re-check the requirement that uses it	Wood (IBC 2009)
Re-check the requirement that uses it	Wall Construction (IRC 2009)
Re-check the requirement that uses it	Fire and Smoke Protection Features (IBC 2009)
Re-check the requirement that uses it	Roof Assemblies and Rooftop Structures (IBC 2009)
Confirm the dependent definition	Cubic Foot
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.

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 fiberboard?

The International Building Code (IBC) 2009 defines it in Wood as: “A fibrous, homogeneous panel made from lignocellulosic fibers (usually wood or cane) and having a density of less than 31 pounds per cubic foot (pcf) (497 kg/m3) but more than 10 pcf (160 kg/m3).” 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 fiberboard?

In this corpus the term is used across 12 chapters, led by Wood in the IBC 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 fiberboard used for?

In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Wood: “A fibrous, homogeneous panel made from lignocellulosic fibers (usually wood or cane) and having a density of less than 31 pounds per cubic foot (pcf) (497 kg/m3) but more than 10 pcf (160 kg/m3).” It is defined in IBC 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 are the building classifications used in building codes based on?

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 fiberboard, which the IBC 2009 defines as “A fibrous, homogeneous panel made from lignocellulosic fibers (usually wood or cane) and having a density of less than 31 pounds per cubic foot (pcf) (497 kg/m3) but more than 10 pcf (160 kg/m3).” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

What are the IBC equipment platform requirements?

Equipment Platform is a separate defined term. The IBC 2009 defines it as: “An unoccupied, elevated platform used exclusively for mechanical systems or industrial process equipment, including the associated elevated walk-ways, stairs, alternating tread devices and ladders necessary to access the platform (see Section 505.5).” That is not the same as fiberboard, which the IBC 2009 defines as “A fibrous, homogeneous panel made from lignocellulosic fibers (usually wood or cane) and having a density of less than 31 pounds per cubic foot (pcf) (497 kg/m3) but more than 10 pcf (160 kg/m3).” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted.

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