Required fire flow calculator for IFC Appendix B.
Pick the construction type, enter the fire-flow calculation area and say whether the building is sprinklered. The required fire flow and its duration come from Tables B105.1 and B105.2, with the sprinkler reduction applied the way the appendix applies it. Free from FireInspection360, the fire prevention platform built by fire inspectors.
Calculate the required fire flow
Table B105.1(2) by construction type and fire-flow area, Table B105.1(1) for a one- or two-family dwelling of 3,600 square feet or less, and the Table B105.2 sprinkler reduction. The 2021 IFC tables; the numbers have not changed since the 2012 edition.
Fire flow is the water a building needs before the first engine arrives.
IFC Appendix B answers one question for a fire code official reviewing a site plan: how many gallons per minute, for how long, must the water supply deliver to control a fire in this building? Section B104 defines the fire-flow calculation area as the total floor area of all floors, measured to the outside of the walls, and Table B105.1(2) turns that area and the building's construction type into a flow and a duration. A Type V-B wood-frame building needs more water for the same area than a Type I-A high-rise, because the table is built on how much of the building is expected to burn at once.
Sprinklers change the answer more than anything else on the page. Table B105.2 lets the required fire flow for a building sprinklered throughout drop to a quarter of the table value, though never below 1,000 gallons per minute for an NFPA 13 system or 1,500 for an NFPA 13R system, and the duration then follows the reduced flow back into Table B105.1(2). One- and two-family dwellings of 3,600 square feet or less have their own table: 1,000 gallons per minute for an hour, halved to 500 for 30 minutes when the house is sprinklered. Section B103 also lets the fire code official reduce the figure where the water supply cannot support it, or double it where exposure to neighbouring buildings makes a conflagration likely, and that decision is the official's, not a table's.
The required fire flow is only half of the comparison. The other half is what the hydrants near the building can actually deliver at 20 psi residual pressure, read from a flow test. A required fire flow of 3,000 gallons per minute in a district whose hydrants flow 1,200 is a plan review finding before it is a fire, and it is the kind of finding that only shows up when the two numbers sit on the same record.
How FireInspection360 keeps the two halves on one record
Every property in FireInspection360 carries its construction type, floor area, occupancy and sprinkler systems, so the required fire flow is calculated on the record itself, with the department's own amendment to the sprinkler reduction applied. The nearby hydrants' flow tests sit beside it, and the fire flow map paints every building in the district by whether the hydrants within reach can meet what it needs.
Related tools: hydrant flow test calculator (the available flow at 20 psi) and the hydrant flow class chart.
See the whole platform with your own property records.
A one-hour walkthrough with a fire prevention expert, or the demo site right now.