fire rating of the roof assembly

[gradfire]

Hello everyone,

could any one please help me with below query.

Query Is to give fire rating for roof of steel billet casting plant which falls under TYPE II(222) considering large shed area. Here required fire resistance is 1 hour. And height of the roof is 25 meter. Plant has got exterior wall for only 60 percentage of perimeter. Is there any NFPA exception in your knowledge can we use to allow non-fire rated roof assembly.

As per 7.2.3.2.8 of NFPA 5000 Roofs 20 ft (6100 mm) or More Above Any Floor. In
occupancies other than mercantile, industrial, or storage occupancies
with ordinary or high hazard contents, or other occupancies
with high hazard contents exceeding the maximum
allowable quantities (MAQ) per control area as set forth in
34.1.3, the fire-resistive protection of the roof/ceiling assembly
required by Table 7.2.1.1 shall not be required where every
part of the roof/ceiling assembly is 20 ft (6100 mm) or more
above any floor immediately below.[/b]

Above can not be used since this is ordinary hazard occupancy housing steel metal working. But still I would like to know if we can allow non fire rated roof having height of 25 meter.

Waiting for some quick response.

Cheers guys

 

[stookeyfpe]

I preface my response by informing you I have very little experience with NFPA 5000.

Maybe I am missing something but the section you cited doesn't require 1-hour fire-resistant assemblies in Industrial or Storage occupancies. A building storing steel billets (Storage occupancy) or associated with its manufacturing (Industrial Occupancy) clearly qualifies for not requiring a fire-resistive assembly on the roof deck, based on the cited section of NFPA 5000.

 

[gradfire]

Thank you sir for your response.

here code allows non fire rated roof assembly for occupancies other than industrial and storage occupancy with ordinary or high hazard contents. here occupancy has got ordinary hazard classification so mentioned clause can not be used.

Best Regards.