In brief
Under Art. 99 of the Regulation on the Fire Protection of Buildings, 1 extinguisher with 6 kg of dry chemical powder or equivalent is kept for every 500 m² of building construction area in the low hazard class and every 250 m² in the medium and high hazard classes. The distance from any point to an extinguisher is at most 25 m, and devices of 4–12 kg are mounted at a height not exceeding about 90 cm from the floor. Wheeled extinguishers are additionally placed in car parks, warehouses and plant rooms.
Calculating the number of fire extinguishers: what does the regulation say?
Calculating the number of fire extinguishers is based on Art. 99 of the Regulation on the Fire Protection of Buildings. The second paragraph of the article gives the basic rule: 1 for every 500 m² of building construction area in the low hazard class, and 1 for every 250 m² in the medium and high hazard classes, of a suitable type of 6 kg dry chemical powder (DCP) or equivalent gaseous fire extinguishing device.
When applying this rule, note three points:
- The calculation area is the "building construction area". Not just the production area; warehouses, corridors, offices and social areas are also included in the calculation.
- The number is always rounded up. For a medium hazard area of 1,100 m², the result 1,100 / 250 = 4.4 means 5 units.
- The calculated number is a minimum. Art. 99/1 requires the type and number of extinguishers to be determined according to the conditions and risks in the spaces. Even if the area calculation gives a sufficient number, the 25-metre rule or special risks may require more devices.
Paragraph 2 of the Regulation does not set a separate "at least so many on each floor" rule. However, the 25-metre rule and the requirement to place devices in a distributed way make it necessary in practice for there to be extinguishers on every floor and in every independent section.
Determining the hazard class
The first step in the calculation is to find the hazard class of the building or section. Art. 19 of the Regulation divides buildings into low, medium and high hazard classes and gives examples in Annex 1:
- Low hazard: places where the fire load and combustibility are low.
- Medium hazard: places where the fire load and combustibility are at a moderate level. The examples in Annex 1 include shops and offices, car parks, woodworking and furniture factories (excluding foam plastics), and automotive factories and repair shops.
- High hazard: places where the fire load is high and fire can spread quickly. The examples in Annex 1 include chipboard factories, plastic foam and sponge manufacturers, and paint manufacturing.
This classification is different from the NACE-based hazard class in OHS legislation. A workplace may be in the "hazardous" class for OHS purposes but in the medium hazard group under the fire regulation. Match your own activity against the table in Annex 1; where you are not sure, obtain the opinion of the local fire brigade, as Art. 99 also provides.
Calculation with a sample floor plan
Consider a two-storey furniture workshop. The workshop is treated as medium hazard; for the office floor too, since it is part of the same building, the calculation has been made on the medium hazard basis as a precaution.
| Section | Area | Calculation | Minimum units | Note |
|---|---|---|---|---|
| Ground floor production area | 1,200 m² | 1,200 / 250 = 4.8 | 5 | Distributed according to the 25 m rule |
| Ground floor raw material and finished goods warehouse | 300 m² | 300 / 250 = 1.2 | 2 | Plus a wheeled extinguisher (Art. 99/3) |
| Boiler room | 25 m² | Special rule outside the area calculation | 1 | At least 1 x 6 kg multi-purpose DCP (Art. 54) |
| Upper floor office and canteen | 450 m² | 450 / 250 = 1.8 | 2 | 1 near each stair exit |
| Total | 10 + 1 wheeled |
Rounding the sections separately usually gives a safer result than dividing the total area in one go, and also makes placement easier. The calculation based on the total area (1,975 m² / 250 = 7.9 → 8) shows the minimum number; placement section by section shows the real need on site.
The 25-metre rule and extinguisher placement
Under Art. 99/4, the distance to reach extinguishing devices is at most 25 m. Measure this distance not as the crow flies, but along the route the worker would actually walk; machines, racks and partition walls lengthen the route.
The same paragraph sets the following rules for placement:
- Extinguishers are placed near walkways and doors, in a distributed way and so that they can be seen.
- They are placed in easily accessible places, for example inside or near fire hose cabinets.
- They are not placed behind doors, in closed cupboards other than fire hose cabinets, in deep wall recesses, or on or near heaters.
- If their location is partly hidden, it is indicated with suitable photoluminescent signs.
In the sample workshop, 5 devices distributed along the long side of the 60 m × 20 m production area, near the two side doors and the central corridor, provide a 25 m walking distance from every point in the area. If there are corners between rows of racks, additional devices may be needed.
Mounting height: the 90 cm rule
Under Art. 99/5, extinguishers weighing between 4 kg and 12 kg are mounted so that their height from the floor does not exceed about 90 cm, and the wall bracket must allow them to be removed easily. The aim is for the device to be picked up in one movement by workers of different heights.
Common mistakes seen on site are: the device being blocked by pallets or boxes, being left on the floor where it ends up in a forklift route, the bracket being screwed in place so the device cannot be removed, and the sign being at a different point from the device's location. We covered the rules for signs in our article on health and safety signs.
Distribution by type: which extinguisher at which point?
Art. 99/1 sets the type of extinguisher according to the class of fire: for class A fires, primarily multi-purpose dry chemical powder or water extinguishers; for class B, primarily dry chemical powder, carbon dioxide or foam; for class C, primarily dry chemical powder or carbon dioxide; and for class D metal fires, primarily dry metal powder extinguishers. Placing wheeled extinguishers in car parks, warehouses and plant rooms is additionally mandatory (Art. 99/3).
The number of 6 kg DCP units from the calculation is a general baseline; you also need to select the appropriate type for electrical panels, kitchens, flammable liquid areas and sections where metal dust is produced. We explained the consequences of choosing the wrong type, with examples, in our article on types of fire extinguisher.
Maintenance, inspection and training
As well as number and placement, it matters that the device is in working order. Under the Regulation, portable extinguishers must carry the TS 862-EN 3 quality certificate and wheeled extinguishers must conform to TS EN 1866. Periodic inspections are carried out according to TS ISO 11602-2: devices undergo a general check once a year, and at the end of the fourth year the extinguishing agent is replaced and a hydrostatic test is carried out. The service company leaves an equivalent device in place of a device taken for maintenance. We explained the inspection and refilling calendar in detail in our article on fire extinguisher inspection and refilling; you can add the dates to the OHS renewal calendar.
The people who will use the device are also part of the calculation. Under OHS legislation, at least 1 support staff member is assigned to the firefighting team for up to every 30 workers in very hazardous, 40 in hazardous and 50 in less hazardous workplaces, and a drill is held at least once a year. For a team that does not know how to use an extinguisher, choosing the right location for the device is not enough. We provide theoretical and practical fire training; we also deal with extinguisher placement and the evacuation drawing as part of emergency plan work. For the general structure of the plan, see our article on how to prepare an emergency plan.
Frequently Asked Questions
One fire extinguisher is needed for how many square metres?
1 extinguisher with 6 kg of dry chemical powder or equivalent is needed for every 500 m² of building construction area in the low hazard class and every 250 m² in the medium and high hazard classes. The result is always rounded up.
How high off the floor is a fire extinguisher mounted?
Extinguishers between 4 kg and 12 kg are mounted so that their height from the floor does not exceed about 90 cm. The bracket must allow the device to be removed easily.
Should there be a fire extinguisher on every floor?
The Regulation has no separate "every floor" rule, but the distance from any point to an extinguisher must be at most 25 m and devices must be placed in a distributed way. When these two rules are applied together, there must be an extinguisher on every floor.
Does having sprinklers reduce the number of extinguishers?
Paragraph 2 of Art. 99 provides no exception for buildings with sprinklers. Even if there is a sprinkler system, the number of portable extinguishers is calculated according to the same rule.
Fire classes, choosing the right extinguisher, hands-on extinguishing in a safe open area and an evacuation drill, all in one training.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.