Coffee Break Training: Access and Water Supplies: Fire Flow Formulas: Part 8: Insurance Services Office Needed Fire Flow Formula: Effective Area Exemptions   [open pdf - 532KB]

"The effective area, Ai, in the ISO [Insurance Services Office] construction factor formula, Ci = 18F√(Ai), is subject to adjustment by fire-resistive 'division walls,' but there also are spaces that ISO specifically exempts from inclusion as part of the effective area variable. When calculating a building's effective area, the ISO NFF [Needed Fire Flow] allows the following spaces to be omitted: [1] Mezzanines that are less than 25 percent of the square footage (meters squared) of the floor immediately below. [2] Courts without roofs. [3] Roof structures, sheds or similar constructions. [4] In breweries, malt mills and similar occupancies, slatted operating decks and walkways that have no storage. [5] In nonsprinklered buildings (or buildings that do not meet the ISO criteria to qualify as 'sprinklered'), floors that are protected by approved sprinklers or automatic fire suppression systems with no high fire hazard occupancies on the floor. [6] Basements or subbasements that are vacant, are used only for building maintenance, or have noncombustible or limited combustible contents."

Report Number:
Coffee Break Training - Fire Protection Series No. FP-2013-43
Public Domain
Retrieved From:
United States Fire Administration: http://www.usfa.fema.gov/
Media Type:
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