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TOPIC: General Discussion

Class A Assembly

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Hello Experts, I have metal roof ona residential project. The City requires a Class A assembly for the roof. I find information as to how to test for the assembly, but no information as to the actual construction materials that make up the assembly. I have to draw a detail of the roof construction that will achieve the Class A assemble. Can you help me? Thank you for your time, Susu
Guest User

6/15/2006
I believe that under the current ICC code, if you have a steel roof covering, it automatically receives Class A, regardless of the rest of the assembly. However, if that is not the case, then you need to contact the manufacturer of the roofing and see how their product was installed when it passed Class A testing. That will vary from product to product. Todd Miller
Todd Miller
Isaiah Industries, Inc.

6/15/2006
Thanks for the quick reply. The spec'd metal roofing is Follansbee and they will not advise me how to achieve the Class A assembly. Also, the plan checker that is requesting this requirement can not assist me. He was not aware how to construct the assembly. We are under the CBC (California Building Code) and I can not find any info there. I will try your suggestion on the plan checker to get a response and opinion. Thanks again.
Guest User

6/15/2006
Currently there is no California building code. They used the Unified Building Code however it merged into the International Building Code in 2001. California then adopted the Fire Code 5000 but then it was cancelled and they are in the process of adopting the IBC. Currently the former UBC and the new IBC has grandfathered metal roofing as a class A assembly in new construction however in a roof over, the assembly must be tested. Also some cities and counties have their own additional requirements such as the City of LA. I would recommend using a product called Versa Shield manufactured by Elk as an underlayment as it has been tested and carries approval for fire ratings under metal roofing. Go to the ICC (International Code Council) and look up the product approval and I am sure it provides an A rating with either one ot two layers.
Allan Reid
Dura-Loc Roofing Systems, Inc.

6/16/2006
Similar question, but instead a Class B roof is required. What assembly meets a class B? Is the only way to get a class A or B rating with and underlayment material?
Guest User

11/26/2007
In many cases, steel roofing will achieve Class B without a special underlayment. However, you must consult local codes as well as the roofing manufacturer and their code listings. Todd Miller
Todd Miller
Isaiah Industries, Inc.

12/1/2007
Generally if you install densedeck over your substraight and then you underlayment then the panel that will give you a class a fire rating
Guest User

3/20/2008
Yes. Todd Miller
Todd Miller
Isaiah Industries, Inc.

3/21/2008
Yes, all metal roofing has a default class A rating. However, unless you can design a way to just put metal roofing on the building without a support system (i.e. floating), the entire assembly has to have a rating. Most often UL or Gypsum Assoc. have rated these assemblies and have drawings you can copy. There is also an FR, NER, and WH TSC, that provide ratings. The manufacturer of the various products involved will have submitted for their product to receive a rating.
Guest User

11/17/2010
If you are seeking a fire rating that meets the fire department req. that is typically just for burn thru from the topside. Most roof coverings meet the min. requirements. And the manufacturer usually has an installation guide to achieve the rating they are talking about. The fire rating that the building department is often requesting, is for the entire roof assembly, from the ceiling of the interior space to the roof surface. Then you need an approved assembly with the UL, GA or other testing agency number referenced on your prints.
Guest User

11/17/2010