When Are Fire Sprinklers Required?
Fire sprinklers are among the most effective fire protection measures available, and the evidence for them is striking. Research by the National Fire Chiefs Council and the National Fire Sprinkler Network found that sprinklers operated as intended in around 94 per cent of relevant fires, and controlled or extinguished the fire in some 99 per cent of cases where they operated, across both residential and non-residential buildings. Given numbers like those, the question we are often asked is a reasonable one, namely when sprinklers are actually required by law, and the honest answer is that the rules in this country are a patchwork that catches fewer buildings than many people assume.
When are sprinklers required in commercial buildings?
The legislation around sprinklers in commercial premises is genuinely hard to follow, and that difficulty is itself part of the story. There is no single square-metre figure that triggers a sprinkler requirement across the board. Instead, Approved Document B Volume 2 sets out a series of different compartment size limits and height triggers depending on the purpose group of the building, so a shop, a warehouse and a multi-storey office each face a different threshold. As a general guide, un-compartmented shops and self-storage buildings can be expected to need sprinklers from around 2,000 square metres, while the largest single-storey storage and distribution buildings carry a much higher limit of around 20,000 square metres before sprinklers become expected. There is also a separate provision expecting sprinklers in a number of non-residential purpose groups, including offices, shops, assembly and recreation, industrial and storage buildings, once the building rises above around 30 metres. It follows that a mid-sized commercial building can very much be caught by a Building Regulations sprinkler trigger; the figures simply depend on the specific building type and configuration, and the applicable table in Approved Document B Volume 2 needs to be checked for the building in question rather than relying on a single headline figure.
Separately from Building Regulations, every Responsible Person must carry out a suitable and sufficient fire risk assessment under the Regulatory Reform (Fire Safety) Order 2005, and keep it recorded and up to date. The assessment itself can conclude that sprinklers, or another form of suppression, are a necessary measure for a particular building, even where no specific Building Regulations trigger applies. In practice, for a great many existing commercial premises, the risk assessment is what actually determines whether suppression is needed, rather than a compartment size figure in the guidance.
When are sprinklers required in residential buildings?
The residential picture has moved more decisively, and in the right direction. Before 2020, the statutory guidance in England recommended sprinklers only in buildings taller than 30 metres built since 2007, with existing high-rise buildings expected to install them when a fundamental change was made to the structure or use.
In May 2020, amendments to Approved Document B Volume 1 lowered that threshold substantially, so that new blocks of flats with a top storey more than 11 metres above ground level should now be provided with sprinkler protection. The guidance generally requires sprinklers within the individual flats themselves, rather than in fire-sterile common areas such as stairs, corridors and landings, which do not need to be sprinklered separately. Systems should be installed to BS 9251, the standard for residential and domestic sprinkler systems, or to BS EN 12845 for blocks that fall outside the scope of BS 9251. BS 9251 covers a broad range of residential settings, including individual houses, flats and maisonettes, houses in multiple occupation, boarding houses, blocks of flats and residential care premises. Separately, since March 2025 sprinklers have been required in all new care homes in England under Approved Document B, irrespective of height, reflecting the particular vulnerability of people who cannot evacuate without help.
One significant gap remains. Building Regulations are generally not retrospective, so existing residential blocks are not automatically required to be upgraded simply because later guidance introduces a lower sprinkler threshold. Sprinklers can still become relevant to an existing building where substantial building work, an extension, or a material change of use brings the current guidance into play, for example where work creates new residential accommodation above the 11 metre threshold, but outside those circumstances a great many older blocks remain without sprinkler protection.
The unsettled question of schools
Schools are the area where the position has shifted most recently, and not in the direction many in the sector hoped for. It is worth being clear that sprinklers in schools have never been a general Building Regulations requirement in the way the residential 11 metre threshold is; the expectation instead sat in Building Bulletin 100, the Department for Education's own design guidance, which is a policy document rather than statutory guidance under Approved Document B. For years, Building Bulletin 100 set the expectation that all new schools should be designed with sprinklers except in a few low risk cases, although in practice only a minority of new schools were ever fitted with them. In January 2026 the Department for Education published a new school building specification stating that the 2007 version of Building Bulletin 100 is no longer required, and limiting the expectation of automatic suppression to new school buildings that are at least four storeys or 11 metres in height, that contain residential accommodation, or that are special schools and colleges. This is a change to DfE policy for schools it funds, rather than a change to the Building Regulations themselves, though in practice it removes the main driver that previously led most new schools to include sprinklers.
The change drew strong objections from across the fire safety and construction sectors, including the Construction Industry Council, the National Fire Chiefs Council and the Fire Protection Association, which has long called for sprinklers to be required in all new school builds and significant refurbishments. It is worth noting that the position differs across the United Kingdom, since sprinklers are mandatory in new and refurbished schools in Scotland and a condition of grant funding in Wales, while England and Northern Ireland do not require them in the same way. For most ordinary new schools in England, the practical consequence is that suppression now sits with the building's own fire strategy and risk assessment, rather than being a near-automatic expectation as it was under the previous guidance.
Regulation is a floor, not the whole answer
The thread running through all of this is that the legal requirements set a minimum, and they catch a narrower range of buildings than the evidence on effectiveness might suggest they should. A building can fall well outside every mandatory trigger and still be one where sprinklers are the most sensible measure, whether for life safety, for protecting an irreplaceable building, or for the business continuity that matters so much when a fire would otherwise put an organisation out of operation for months. Insurers increasingly take the same view, and may look for suppression where the law does not require it. The place where all of these considerations are weighed up properly is the fire risk assessment, which is where the question of whether your particular building needs sprinklers should actually be answered.
Why our advice on this is impartialWe do not sell, design or install sprinkler systems, so we have no commercial interest in whether you fit them. When we assess your building, we tell you whether the guidance requires suppression and whether the risk justifies it regardless, giving you an objective basis for a significant decision rather than a recommendation from someone who stands to win the installation contract.
If you are unsure whether your building is required to have sprinklers, or whether they would be a sound investment even where they are not mandatory, the most reliable way to find out is through a competent fire risk assessment that considers suppression alongside everything else. As independent assessors covering the North West, North Wales and the West Midlands, we are glad to give you a clear and impartial view.
Wondering whether your building needs sprinklers?
We can assess whether suppression is required for your premises, and whether the risk justifies it regardless, as part of a fire risk assessment, with no systems to sell you either way. If you would like to discuss it, please get in touch.
Get in touch Fire Risk AssessmentsThis article is provided for general guidance and does not constitute professional advice for any specific premises. It refers to Approved Document B Volume 1 (Dwellings) and Volume 2 (Buildings other than dwellings), the Regulatory Reform (Fire Safety) Order 2005, BS 9251, BS EN 12845, the 2018 Independent Review of Building Regulations and Fire Safety, and Department for Education guidance current at the time of writing. The specific compartment size and height triggers in Approved Document B Volume 2 vary by building type, purpose group and configuration, and this article summarises the general position rather than every applicable table. Considerable care has been taken to ensure accuracy at the time of writing, but legislation and guidance change over time and any figures should be checked against the current Approved Document before being relied on. Fletcher Risk Management Limited provides Fire Risk Assessments, Fire Door Inspections and Fire Safety Training across the North West, North Wales and the West Midlands.