Applying the IBC: What Does 'Exterior' Mean in Chapter 14?

Originally published by the following source: SBC MagazineOctober 4, 2018
by Sean Shields and Kirk Grundahl, P.E.


Training provided by the International Code Council (ICC) for members of its review committees (e.g. Structural Committee) focuses first on key definitions, the scope statement of each relevant section and then the charging or implementing language. This approach helps anyone seeking to apply a section of the building code understand its intent and function.

To that end, there has been recent confusion over the following section of the building code regarding “exterior wall coverings” in Types I and II construction:



This then refers to section 603, Combustible Material in Types I and II Construction, which outlines the allowable materials as follows:



There are twenty-six (26) exceptions that allow alternative combustible materials to be used in “exterior wall covering” “applications, the first four examples follow:



One of the exceptions that is causing confusion currently is #13:



Where there is a combustible  exterior wall covering, Chapter 14 applies.

The first question that needs to be addressed. What do the  key definitions mean?  

These are generally found in Chapter 2, Definitions.

  1. Combustible – Since combustible is not a defined term the IBC says to use its ordinarily accepted meaning such as the context implies. Therefore, combustible means:



  1. Exterior – Since exterior is not a defined term, exterior then means:



  1. Exterior Wall Covering is defined in Chapter 2 as follows. Also provided are all Chapter 2 definitions that use this as a defined term to provide the implied context.



Then the question is how does Chapter 14 apply?

Since we are dealing with combustible  exterior wall coverings, Section 1406 Combustible Materials on the Exterior Side of Exterior Walls applies, which has the following specific scope and implementation language:




Given the definitions above, this means that this section only applies to material exterior to the water-resistive barrier, which is defined as:



This brings the focus onto the true exterior most surface of the wall assembly for the building. A good example of a “wall assembly” is a fire barrier, which is defined as follows:



Another good example of the “floor, wall, or roof assembly” concept is the well-known one-hour or two hour rated fire endurance assembly, which is often generically known as a “UL assembly”,  but can be found in a research report by any ANSI ISO/IEC 17065 accredited certification organization.

The goal has to be to allow as many alternatives as possible to provide free and open markets (link is external), which are the foundation of economic competition, innovation and a vibrant economy. (link is external)

With the word exterior  as the focus, Section 1406.2 shall apply as follows:



Here, any foam plastics used on the exterior of the building need to comply with Chapter 26. For other exterior applications Section 1406.2.1 applies:



For clarity and ease of use, Section 1406.2.1 only applies to the  exterior surface of a building. Exterior  in this case means “exterior to the water resistive membrane”.

If building application requires performance of an “assembly”, the test methods typically used to assess assembly performance are ASTM E119, NFPA 285, NFPA 286, etc., along with any associated engineering analysis using accepted engineering practice.

For additional information, please review the following articles:

  1. NFPA 285 and Code Conforming Design – Reliable or Not?
  2. For more in-depth information on fire safety and the use of foam sheathing, read this recent document created by the American Chemistry Council’s Foam Sheathing Committee (FSC).
  3. Understanding Fire Safety and the Use of Foam Sheathing
  4. ICC Provides Perspective on Combustible 'Cladding Systems'
  5. Post Grenfell, Do You Know the Code and Your Cladding Options?
  6. Would Smoke Alarms and Sprinklers Have Saved Grenfell's Installed Cladding?
  7. London's Grenfell Fire: Will Plastics Be Inappropriately Blamed?
  8. What Does the Code Say 'Accepted Engineering Practice' Means?
  9. Building Code & Adopted Law Definitions -- Building Official
  10. What is a Building Official’s Scope of Work?
  11. Building Code Adoption of Innovative & Engineered Products
  12. Building Code Adoption Where Intellectual Property (IP) is Involved
  13. Do You Indemnify & Hold Harmless Your 'ICC Report' Author?
  14. APA’s Dr. Yeh on Design Values & Responsibility
  15. Does Your Teammate Sign and Seal Their Testing and Engineering Work?
  16. Confidence Through Sealed Engineering, No Seal=No Teammate