Explore The Different Fire Sprinkler System Categories
There are a range of different types of sprinkler systems, so it's important that you know which category your property falls under.
Category 1 Sprinklers - Low Risk Domestic Dwellings
Category 1 fire sprinkler systems are designed for individual domestic dwellings with low fire risk. This includes single-family homes, bungalows and individual flats within low-rise buildings.
These properties typically have straightforward layouts, easy means of escape, and fewer occupants, reducing the likelihood of fire spread or evacuation difficulties
The following should be considered before installing Category 1 sprinklers
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Head risk: Calculations should allow for the operation of one sprinkler head.
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Water provision: The system must be capable of delivering 60–100 litres per minute, depending on room size.
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System run time: Water supply should sustain operation for a minimum of 10 minutes.
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System type: Typically connected directly to the mains water supply, however can also be connected to dedicated pump and tanks if mains water pressure isn't adequate.
Category 2 Sprinklers - Medium Risk Residential Buildings
Category 2 systems are suitable for medium-risk residential buildings, including two or three-storey apartment blocks (under 18 metres), larger houses in multiple occupation (HMOs), and properties with vulnerable residents.
These buildings involve more complex layouts and increased occupancy, which raises the fire risk compared to single-family dwellings.
The following should be considered before installing Category 2 sprinklers
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Head risk: The system should be designed to operate up to two sprinkler heads simultaneously.
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Water provision: Capable of delivering up to 200 litres per minute.
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System run time: Must maintain flow for a minimum of 30 minutes.
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Additional features: Requires backflow protection to prevent contamination of potable water supplies. Dedicated water storage or booster systems may be used where mains supply is inadequate.
Category 3 Sprinklers - High Occupancy Residential Buildings
Category 3 covers buildings with higher occupancy levels or vulnerable residents, such as care homes, student accommodations, boarding houses and hostels.
These environments often house people who may need assistance during evacuation or are at more risk of accidently creating a fire, increasing fire safety challenges.
The following should be considered before installing Category 3 sprinklers
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Head risk: Must allow for the simultaneous operation of up to four sprinkler heads.
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Water provision: The system must deliver up to 300 litres per minute, depending on building layout. Typically features a dedicated water storage tank and fire pump to maintain consistent pressure and flow.
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System run time: Requires at least 30 minutes of sustained water flow.
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Additional features: As with all residential fire sprinkler systems, the system must be connected to an audible alarm.
Category 4 Sprinklers - High Risk, High Rise Residential Buildings
Category 4 applies to residential buildings taller than 18 metres, such as high-rise apartment blocks and mixed-use developments with residential upper floors.
These systems were introduced after the Grenfell Tower fire and are designed to provide reliable protection in the most complex and hazardous environments.
The following should be considered before installing Category 4 sprinklers
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Head risk: Calculations must account for the simultaneous operation of four sprinkler heads.
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Water provision: Requires capacity to deliver up to 400 litres per minute.
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System run time: Must provide a minimum of 60 minutes of continuous water supply.
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System reliability: Requires dual storage tanks and a backup power supply (e.g., UPS or generator) to maintain pump operation during outages.
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Monitoring: Includes electronic monitoring of all control valves and alarms for faults, pump failures or low water levels.
