Fuel MAQ Limits Per Building, If 3-Hr Separated?

I’m working on a super high-rise scheme, five towers over a common 9-story podium. Towers are more than 12 m apart; no connection above podium level; transfer slab is 3-hour rated and sprinklered throughout.

Client is proposing 2 x 2,500 L diesel tanks at the lower technical floor of each tower plus a 900 L tank at each roof technical floor, so 5,900 L per tower and 29,500 L across the development.

The issue is that IBC Section 605.4.2.2 sets the aggregate fuel oil quantity on a per-building basis, with a maximum of 3,000 gallons (11,350 L) where protected above-ground tanks to UL 2085 are used in a sprinklered building. Per tower, we are within that limit, but across the development as a single building, we are not, by a wide margin.

​If the podium is 3-hour separated from all towers above, can I take a separate fuel limit for each tower, or do I have to add up the fuel across all five towers on the basis that the development is a single building?

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