Genset building classification

[ATSE]

a. What is the occupancy classification for a CMU building housing a diesel generator set ("genset") with a 500 to 900 gallon belly tank (double wall)? IBC 2009. I'm leaning toward U (Utility and Misc).
b. Is 2-hour fire rating required?
c. Is fire suppression required?
d. Is there an NFPA code more applicable, or make more requirements, than IBC?
The building is small CMU (14' x 20') with wood framed roof and one layer of 5/8" gypboard. Double doors one end. Adjacent structure is 10 feet away. Site is unoccupied wastewater pump station.

 

[stookeyfpe]

A. Group U occupancy. It's not intended for occupancy and the housing is designed only to protect the engine and armature.
B. Unable to answer. What's the location of the generator in relation to the property line?
C. No
D. Depends on what codes and standards are adopted in the jurisdiction

 

[ATSE]

stookeyfpe,
Thanks for the reply.
b. Not near a property line.

Variation on question c. There is a second, almost identical structure where roof is simple 2x wood framing (not pre-engineered trusses) with no ceiling or gypboard protection - just exposed wood.
Seems like at least a one-hour ceiling is required, considering both the diesel fuel and the generator. Does the IBC address this?

 

[stookeyfpe]

No. Once it's called a U occupancy, the only limitation is height and area in Table 503, and that's driven by the materials of construction and compliance with Table 601. Automatic sprinkler protection isn't required for any Group U occupancy.