BS9251:2021 – The British Standard for Fire Sprinkler Systems
Overview
BS9251:2021 is the British Standard governing Fire Sprinkler Systems for residential and domestic properties in the UK.
Originally introduced in 2005, it has undergone revisions in 2014 and most recently in 2021, with input from the fire service and key industry professionals to reflect updated best practices and safety requirements.
What is BS9251 – Fire Sprinkler Systems About?
BS 9251 specifies the design, installation, components, water supplies and backflow protection, commissioning, maintenance, and testing of fire sprinkler systems installed for life safety purposes in residential and domestic premises.
It is applicable for sprinkler protection of domestic and residential premises and contains specific recommendations for sprinkler systems in buildings over four stories or above 18m in height, whichever is lower.
Note: In buildings with a mix of residential, non-residential, and commercial use, it is generally appropriate to protect the residential areas using BS 9251 and the non-residential parts using BS EN 12845.
Who is BS9251 – Fire Sprinkler Systems For?
BS 9251 applies to:
- Architects and engineers
- Sprinkler design, installation, and maintenance companies
- Public and private building owners
- Insurers and contractors
- Fire-extinguishing companies
Why Should You Use BS9251 – Fire Sprinkler Systems?
Installing fire sprinkler systems in residential complexes is a crucial safety measure that reduces the risk to both life and property. Key benefits include:
- Life Safety: Fire sprinkler systems help contain or extinguish fires, giving occupants valuable time to escape.
- Property Protection: Limits damage caused by fire, reducing repair and rebuilding costs.
- Firefighter Assistance: Helps firefighters by limiting fire development, reducing the risks they face during rescue operations.
- Water Efficiency: Reduces water usage for firefighting by upwards of 90%, minimising environmental impact.
- Regulatory Compliance: Ensures buildings meet current safety standards and improves resilience in high-risk scenarios.
- System Modification Support: Aids in system extensions, repairs, or modifications to maintain compliance.
Scope of BS9251
This standard applies to sprinkler systems in the following types of properties:
- Individual dwellings (houses, flats, and maisonettes)
- Houses of multiple occupancy (HMOs)
- Bed and breakfast accommodation
- Boarding houses
- Blocks of flats
- Residential care premises
- Dormitories
- Hostels
Exclusions
BS9251 does not cover:
- Schools
- Hospitals
- Hotels
- Commercial buildings
For commercial properties, the appropriate standard is BS EN 12845:2021.
Risk Categories
The types of buildings covered by BS9251 vary in size, function, and resident profile. As a result, they are divided into four risk categories, each with specific requirements for water supply and sprinkler head operation.
Category 1
Applies to:
- Individual dwellings (houses, flats, maisonettes)
- HMOs
- B&Bs and boarding houses
System Requirements:
- Minimum run time: 10 minutes
- Number of heads for calculation: 1 or 2
- Flow rate: 84-100 litres per minute
- Tank size: 1m³ to 1.5m³
Category 2
Applies to:
- Blocks of flats under 18m (typically up to 6 floors)
- Small residential care homes
- Sheltered and extra-care housing
System Requirements:
- Minimum run time: 30 minutes
- Number of heads for calculation: 1 or 2
- Flow rate: 84-100 litres per minute
- Tank size: 3m³ to 4.5m³
Category 3
Applies to:
- Large residential care homes
- Student accommodation
- Dormitories
- Hostels
System Requirements:
- Minimum run time: 30 minutes
- Number of heads for calculation: 2 or 4
- Flow rate: 168-200 litres per minute
- Tank size: 6m³ to 9m³
Category 4
Applies to:
- Blocks of flats 18m or higher (typically 6 floors or more)
System Requirements:
- Minimum run time: 60 minutes
- Number of heads for calculation: as per Category 3
- Multiple tanks, each capable of providing at least 50% of the required water supply
- Backup power supply
What’s Changed Since the Last Update?
BS 9251:2021 supersedes BS 9251:2014. Key changes include:
- New Category 4: For taller residential buildings (above 18m) and high-risk scenarios.
- Alignment with Fire and Rescue Service national operational guidance for access and response times.
- Increased water supply requirements for taller buildings and high-risk premises.
- Additional recommendations for duplicate pumps and reliability improvements.
- Expanded guidance for non-residential areas within protected buildings.
- Enhanced fire service interaction features for better coordination during emergencies.
Additional Areas Covered by BS9251:2021
- Certain non-residential spaces within residential buildings are also covered under BS9251:2021, including:
- Car parking within or beneath flats / domestic garages
- Bin stores and residents’ storage sheds
- Plant rooms (e.g., PTSN / CCTV / electrical rooms)
- Laundry/utility rooms (domestic or institutional, such as in care homes)
- Kitchens (domestic and self-catering, including student accommodation and residential care)
- Foyer/reception areas and small office spaces (e.g., concierge or site management areas)
How Sprinklers Direct Can Help
Sprinklers Direct offers professional design and hydraulic calculation services to determine the exact system demand and optimal delivery method. Our team ensures compliance with BS9251:2021, tailoring solutions to meet the specific needs of your property.
For more information, visit our news blog to stay updated on fire safety regulations.
For expert advice and installation services, contact Sprinklers Direct today.
