How Many Fire Extinguishers Does My Building Need?

The question is the wrong shape

People ask "how many extinguishers per floor?" and expect a number. There isn't one, and the reason is worth understanding, because it also explains why buildings that bought a round number of extinguishers usually fail inspection.

The requirement is derived from three things working together:

1. Floor area — how much space has to be covered
2. Fire class — what could actually burn here
3. Travel distance — how far someone should have to walk to reach a suitable extinguisher

A 2,000 square metre open warehouse floor and a 2,000 square metre partitioned office floor need different quantities, because the partitions change the walking route even though the area is identical.

Fire classes, and why type matters more than count

Using the wrong extinguisher is worse than having none, because it costs the crucial seconds and can actively make things worse. The classes:

Class A — ordinary combustibles: wood, paper, cloth, most plastics. Water and foam work. This is the general office, ward and residential risk.

Class B — flammable liquids: petrol, diesel, solvents, oils, paints. Foam, dry powder and carbon dioxide. Water is wrong; it spreads the burning liquid.

Class C — flammable gases: LPG, piped gas. The first action is isolating the supply. Dry powder for the fire.

Class D — combustible metals: magnesium, sodium, some machining swarf. Requires a special dry powder agent. Ordinary extinguishers are dangerous here.

Class E — electrical equipment that is live. Carbon dioxide or a clean agent, both non-conductive. Never water, never foam. De-energising the equipment where possible converts the problem back to the class of the material actually burning.

Class F / K — cooking oils and fats in commercial kitchens. Wet chemical, which saponifies the oil surface. Water on a burning oil vat produces an explosive steam eruption, which is why a commercial kitchen also needs a fixed hood suppression system rather than relying on portables.

The practical rule: survey what is actually in each area, not what the drawing labels it. A server room in an office building is a Class E area. A generator room is Class B and E. A records store is a heavy Class A load. A pantry with a gas connection is Class C and F.

The travel distance rule

This is the mechanism that converts area into quantity. Under IS 2190, no occupant should have to travel more than the prescribed distance to reach a suitable extinguisher — commonly 15 metres for ordinary occupancies, with shorter distances where the hazard is higher.

Two things about measuring it:

Measure along the walking route. Not in a straight line through a wall or a locked door. A 12-metre straight-line distance can be a 25-metre walk around a partition.

Measure to a suitable extinguisher. A Class A unit 5 metres from a server room does not satisfy that room's Class E requirement. Each risk class present needs coverage within the distance.

Placement details inspectors actually check

Height. Mounted so the top of the unit is within easy reach — typically around 1 to 1.5 metres from the floor for heavier units, and never placed loose on the floor.

Visibility and signage. Clearly marked with appropriate signage, visible from a distance, not tucked behind a door or inside a cupboard.

Access. Unobstructed. Stock, furniture and parked equipment in front of an extinguisher is the most common finding at inspection.

Location logic. Near exits and along escape routes, so an occupant reaching for one is already moving in the direction they should be going — not deeper into the building.

Fixed position. Units marked to their location and returned to it. Extinguishers migrate; the drawing says one thing and the floor says another.

Maintenance is half the requirement

An extinguisher that exists but does not work is a compliance failure and a safety failure. The cycle is monthly visual checks by the occupier, periodic inspection by a competent person, and refilling or hydrostatic testing at the intervals prescribed for the type.

At every half-yearly Form B inspection, a licensed agency will check pressure gauge readings, discharge and refill dates, seals and safety pins, physical condition of the body and hose, the inspection tag, and whether the unit is at its marked location and accessible. See Form A and Form B explained.

Getting it right

The correct approach is a survey, not a purchase order: walk the building, identify the fire classes present in each area, map the actual walking routes, and place units so that every point is within the travel distance of an appropriate type. Then record it on a schedule showing type, rating, location and charge date — which is what the fire authority asks for anyway.

We cover extinguisher selection, supply and refilling as part of that survey.

Related reading

• Fire safety rules for residential buildings
• Fire NOC in Maharashtra: the complete guide