Fire Rating for Roof Assembly

[JKW05]

Where might one find a tested assembly for a concrete slab or a hollow core plank roof deck with polyiso insulation and EPDM roof membrane (no ceiling). This seems like a pretty basic assembly, but I can't find anything in the UL Classifications.

For a plain 6" slab, Table 720.1 (2009 IBC) lists up to ~3-hour rating, but then Section 720.1 says "Where materials that change the capacity for heat disipation are incorporated . . . fire test results or other substantiating data shall be made available to the building official to show that the required fir-resistance-rating time period is not reduced."

Does anyone know if this data exists for this seemingly simple assembly?

Thanks for any assiatance.

 

[JAE]

Try here:

http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/gbxuvhelp.html

or here:

http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/locating.html

 

[stookeyfpe]

I need help understanding this. The IBC doesn't require fire-rated roofs. It does require roof covernings that are ignition-resistant.

Are we talking about a horizontal assembly or are you talking about roof coverings?

 

[JKW05]

I am looking for a horizontal assembly.

 

[stookeyfpe]

Then JAE answered your question. You can also design the horizontal assembly to the prescriptive requirements in IBC 720.1(3).

 

[JKW05]

As I noted in my original post, I have looked into the UL Classifications, but cannot find a UL assembly consisting of a concrete slab with insulation on top. I would think this would not be an unusual construction. IBC Table 720.1(3) shows a ~6 inch slab will provide a 3-hour rating, but the last sentence in Section 720.1 seems to preclude the use of the slab with insulation without additional testing. I was hoping to find some alternate test reference for what seems like a straight-forward assembly.

It seems absurd that even if I use 4-foot thick roof slab, the building code will not permit it for a rated assembly of any duration if I put just an inch of insulation on top.

 

[stookeyfpe]

Have you considered performing calculations in accordance with IBC Section 721 to determine the estimated fire-resistance of the horizontal assembly? It is possible your assembly would meet these requirements.

 

[JKW05]

The only means I see in that section is 721.2.2.3 which requires the use of insulating concrete or mineral board for insulation along with built-up roofing. In order to meet the Energy Code, I would need 8-12 inches of board insulation (8 to 12 layers of 1" board). This puzzles me, because this would provide the same insulating value that I want to provide using polyiso, which Section 720.1 says may reduce the rating.