Class A Flame Spread Rating Affect Assembly?

12/7/2022

If a material has a Class A flame spread rating, can I assume that it does not diminish the rating of a fire-rated assembly?

Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

4 Comments

John A Dalton

12/7/2022 08:12:56 am

No. The fire tests are very different for flame spread and assembly tests. Foamed plastic for instance can have a Class A rating but you wouldn't put it into a fire-rated assembly without some testing. Thanks, John

Alex

12/7/2022 08:17:15 am

Are you asking if a wall with Class A finishes has a fire rating? If so, it may but it will not be treated as a fire rated assembly. Class A finishes include brick, gypsum, and cement exterior finishes.

To achieve a fire rating, the entire assembly will need to be constructed to restrict the spread of fire. Therefore, all openings will need to be protected.

Glenn Berger

12/7/2022 08:25:30 am

If I am reading the question correctly -- You have a fire-rated (wall) assembly and you want to add a finish (partial or full) that has a Class A flame spread rating.

I would say that the fire-rating of the assembly would be not affected with the addition of an interior finish that has a Class A flame spread.

Todd E Wyatt

12/7/2022 08:53:42 am

The fire-resistance rating (FRR) of a building elements (e.g. primary structure), components (e.g. gypsum board), or assemblies (e.g. shaft walls) are tested per ASTM E119 or UL 263. Per 2021 IBC 703.2.1.4, “Where materials, systems or devices that have not been tested as part of a fire-resistance-rated assembly are incorporated into the building element, component or assembly, sufficient data shall be made available to the building official to show that the required fire-resistance rating is not reduced.”

For instance, a nonbearing 2-Hour FRR partition (tested by UL) such as U411 (https://www.buildsite.com/pdf/ulsystems/Installation-Instructions-2115390.pdf) permits “batts and blankets” (Item 3) as part of this assembly. It also includes (6) alternates to these “batts and blankets”. If you were to include a different insulation material not listed in the listed assembly, you would have to consult with the AHJ that the “required fire-resistance rating (was) not reduced.”

2021 IBC Chapter 8 Interior Finishes “contains the performance requirements for controlling fire growth and smoke propagation within buildings by restricting interior finish and decorative materials. The provisions of this chapter require materials used as interior finishes and decorations to meet certain flame spread index or flame propagation criteria and smoke development criteria based on the relative fire hazard associated with the occupancy. The performance of the material is evaluated based on test standards.”

Depending on the Occupancy Group (e.g. Assembly, Residential, Institutional, etc), if the building is sprinklered or not, and the location (e.g. stairway vs corridors vs rooms) of the Interior Finish (wall & ceiling), the Interior Finishes will have a flame spread index & smoke-developed index of Class A, B, or C. The method of attachment (direct or furred or set-out) of the Interior Finishes onto FRR or noncombustible Building Elements is also prescribed. Chapter 8 also addresses “decorative materials and trim”.

Lastly, Chapter 6 Types of Construction 603.1 Allowable Materials includes a list of “combustible materials … permitted in buildings of Type I or II” (e.g. noncombustible) such as “wood nailers for parapet flashing and roof cants.”

Leave a Reply.

Home
Our Cause

The Blog
The Forum

PE Exam Prep
The Toolkit
MeyerFire University

Pricing
Login
Support
Contact Us

MeyerFire.com is a startup community built to help fire protection professionals shine.
Our goal is to improve fire protection practices worldwide. We promote the industry by creating helpful tools and resources, and by bringing together industry professionals to share their expertise.

MeyerFire, LLC is an International Code Council Preferred Education Provider.
All text, images, and media Copyright © 2023 MeyerFire, LLC

We respect your privacy and personal data. See our Privacy Policy and Terms of Service. The views, opinions, and information found on this site represent solely the author and do not represent the opinions of any other party, nor does the presented material assume responsibility for its use. Fire protection and life safety systems constitute a critical component for public health and safety and you should consult with a licensed professional for proper design and code adherence.

Discussions are solely for the purpose of peer review and the exchange of ideas. All comments are reviewed. Comments which do not contribute, are not relevant, are spam, or are disrespectful in nature may be removed. Information presented and opinions expressed should not be relied upon as a replacement for consulting services. Some (not all) outbound links on this website, such as Amazon links, are affiliate-based where we receive a small commission for orders placed elsewhere.

Class A Flame Spread Rating Affect Assembly?

Leave a Reply.

ALL-ACCESS

SUBSCRIBE

COMMUNITY

YOUR POST

PE EXAM

FILTERS

ARCHIVES

PE PREP SERIES