European Fire Sprinkler Standard — Technical Reference
BS EN 12845: European Automatic
Sprinkler Standard Explained
BS EN 12845 is the governing standard for automatic sprinkler system design across the UK and most of Europe. If you are designing, specifying, or procuring sprinkler systems for European projects, this is the standard that controls your hazard classifications, design densities, pipe sizing, and component acceptance criteria.
🕒 11 min read
🏭 EN 12845:2015+A1:2019
🇺🇪 What is BS EN 12845?
BS EN 12845 — formally titled Fixed firefighting systems — Automatic sprinkler systems — Design, installation and maintenance — is the harmonised European Standard published by CEN (European Committee for Standardisation) and adopted nationally across all EU member states and the UK. The current version is EN 12845:2015+A1:2019.
In the UK it is published as BS EN 12845 by BSI and remains in force post-Brexit. In continental Europe it is published under national designations — DIN EN 12845 in Germany, NF EN 12845 in France, UNI EN 12845 in Italy — but the technical content is identical across all national adoptions. It is the European equivalent of NFPA 13, serving the same fundamental purpose: specifying how automatic sprinkler systems must be designed and installed to reliably suppress or control fire.
For engineers, contractors, and facility managers working on European projects, BS EN 12845 is not optional background reading — it is the legally referenced technical standard in most European building regulations, insurance requirements, and fire authority approval conditions. Designing to NFPA 13 alone is generally not sufficient for UK or European project approval, even if the NFPA 13 design would provide equivalent or greater protection.
This guide provides a complete technical overview of BS EN 12845: its scope, the hazard classification system that drives all design parameters, the hydraulic design method, how it compares with NFPA 13, the key clauses practitioners most frequently need, and what the standard means for sprinkler head and component selection. CA-Fire products are manufactured to GB 5135 with NFPA 13 documentation available; this guide also addresses compatibility with EN 12845 requirements.
In This Guide
- Scope & Application — What BS EN 12845 Covers
- Hazard Classification System: LH, OH, HH
- Hydraulic Design Method & Design Points
- Sprinkler Head Requirements Under EN 12845
- Water Supply Requirements
- BS EN 12845 vs NFPA 13 — Key Differences
- Key Clauses Practitioners Need Most
- Component Certification & Third-Party Approval
- Frequently Asked Questions
1. Scope & Application — What BS EN 12845 Covers
BS EN 12845 applies to automatic sprinkler systems used for fire suppression and control in buildings and structures. Its scope includes:
✅ Covered by EN 12845
- Wet pipe systems
- Dry pipe systems
- Pre-action systems (alternate)
- Deluge systems (water spray)
- Residential and domestic systems (Annex G)
- Buildings up to 45 m height (general)
- Storage occupancies including high-rack storage
- Foam-water sprinkler systems (Annex H)
✗ Outside EN 12845 Scope
- Water mist systems (covered by EN 14972)
- Gaseous suppression systems (EN 15004)
- Powder systems (EN 12416)
- Foam only systems without sprinklers (EN 13565)
- Tunnel fire suppression (separate national standards)
- Nuclear facilities (separate national provisions)
The standard is referenced in the Construction Products Regulation (CPR) and underpins the CE marking of sprinkler components in the European market. In the UK, BS EN 12845 is referenced in Approved Documents B (fire safety) and is cited by the Loss Prevention Certification Board (LPCB) and insurer technical requirements. CEA 4001, the predecessor insurance industry sprinkler standard widely used in Europe before EN 12845, has been substantially superseded by EN 12845 but some insurers still reference CEA 4001 requirements as supplementary conditions.
Post-Brexit note for UK practitioners: BS EN 12845 remains the applicable standard in the UK following Brexit. BSI continues to publish and update it as a British Standard. The UK has not developed a divergent national sprinkler standard. UKCA-marked components are required for UK projects; CE-marked components remain acceptable under transitional arrangements in many cases — verify current requirements with the AHJ on each project.
2. Hazard Classification System: LH, OH, HH
BS EN 12845 uses a three-tier hazard classification system — Light Hazard (LH), Ordinary Hazard (OH), and High Hazard (HH) — with Ordinary Hazard divided into four sub-groups (OH1–OH4) and High Hazard divided into storage categories. This classification determines the design density, area of operation, and maximum spacing for each zone.
| Class | Occupancy Examples | Design Density (mm/min) | Area of Operation (m²) | Max Head Spacing | Max Coverage/Head |
|---|---|---|---|---|---|
| LH | Hotels, offices, schools, hospitals, residential blocks, retail shops under 1,000 m² | 2.25 mm/min | 84 m² | 4.6 × 4.6 m | 21 m² |
| OH1 | Light manufacturing, printing, electronic assembly, car parks, food processing (low fire load) | 5.0 mm/min | 72 m² | 4.0 × 4.0 m | 12 m² |
| OH2 | Retail under 4 m rack height, chemical storage (limited), plastics processing, textiles | 5.0 mm/min | 90 m² | 4.0 × 4.0 m | 12 m² |
| OH3 | Woodworking, paper/board manufacturing, medium-density retail storage, paint mixing | 5.0 mm/min | 100 m² | 4.0 × 4.0 m | 12 m² |
| OH4 | High-piled solid combustibles (non-storage class), rubber processing, high-density retail | 5.0 mm/min | 150 m² | 4.0 × 4.0 m | 12 m² |
| HH — Cat I Storage | Palletised/solid-piled non-combustible products in combustible packaging, up to 4 m storage height | 7.5 mm/min | 200 m² | 3.7 × 3.7 m | 9 m² |
| HH — Cat II/III | High-rack plastics, rubber, flammable liquids, up to 8–13 m storage height | 10–17.5 mm/min | 200–300 m² | 3.7 × 3.7 m | 9 m² |
| HH — Cat IV | Aerosols, flammable liquid totes, foam rubber, high-challenge plastics above 8 m | Table-based — specialist design | Specialist design | Varies | Varies |
Hazard classification is not optional and not conservative by default: EN 12845 Table 1 provides an occupancy classification guide, but the designer must assess actual fire load, combustibility, storage arrangement, and ceiling height to select the correct class. Under-classifying (selecting LH for an OH1 occupancy) creates a system that cannot control a fire in the actual hazard. Over-classifying wastes water supply capacity and increases pump and pipe costs unnecessarily. When in doubt between two classes, the higher class must be used — but this should be a documented engineering decision, not a reflexive assumption that drives disproportionate system cost.
3. Hydraulic Design Method & Design Points
BS EN 12845 uses a hydraulic design method based on three parameters that must all be satisfied simultaneously at the “design point” — the most hydraulically demanding area of the system:
D
Design Density
Minimum water application rate in mm/min (litres per minute per square metre) over the design area. Ranges from 2.25 mm/min (LH) to 17.5 mm/min (HH Cat III). Must be achieved at every point within the design area simultaneously.
A
Area of Operation
The floor area over which the design density must simultaneously be delivered — the “design area.” EN 12845 specifies this area for each hazard class (84–300 m²). The design must assume the most hydraulically unfavourable group of heads within this area all activate together.
Q
Water Flow Rate
Total water demand in L/min: Q = D × A. For LH: Q = 2.25 × 84 = 189 L/min minimum. For OH3: Q = 5.0 × 100 = 500 L/min minimum. This figure, combined with the required residual pressure at the design point, defines the water supply requirement and fire pump specification.
The Design Point Concept
EN 12845 §9.5 requires that hydraulic calculations identify the “design point” — the group of sprinklers within the area of operation that creates the highest demand on the water supply. This is typically the highest-elevation heads furthest from the riser, but must be verified for each layout. The calculation must demonstrate that at the design point, with all heads in the area of operation discharging simultaneously, the minimum density is achieved while maintaining the minimum residual pressure at each head (typically 0.5 bar / 50 kPa for K=80 heads).
EN 12845 Minimum Pressures at the Sprinkler Deflector
LH & OH systems: minimum 0.5 bar (50 kPa) at any head in the design area. HH systems: minimum 1.0 bar at any head. Maximum pressure at any head: 5.0 bar (500 kPa) — exceeding this requires pressure regulation. These are the minimum pressures that must be demonstrated at the most remote head in the design area — not the average or inlet pressure.
4. Sprinkler Head Requirements Under EN 12845
EN 12845 references EN 12259-1 as the product standard for automatic sprinkler heads. Key requirements that affect head selection and installation:
K-factor notation
EN 12845 uses the metric K-factor where Q (L/min) = K × √P (bar). K=80 metric (= K5.6 imperial) is the standard head for LH and OH systems. K=115 metric (= K8.0 imperial) is used where higher flow at lower pressure is required. Always confirm which unit system is being used when comparing K-factors across standards — K=5.6 (gpm/psi½) in NFPA 13 equals approximately K=80 in EN 12845 metric notation.
Response type
EN 12845 requires quick response (QR) heads in LH occupancies — consistent with NFPA 13. Standard response is permitted in OH and HH occupancies. QR heads under EN 12845 are defined as RTI ≤ 50 (m·s)½ — the same RTI threshold as NFPA 13. A head meeting the NFPA 13 QR definition will also satisfy the EN 12845 QR requirement.
Temperature ratings
EN 12845 uses the same glass bulb colour coding and temperature rating categories as NFPA 13 (57°C orange through 260°C black). The minimum margin above maximum ambient temperature is 30°C — identical to the NFPA 13 requirement. Temperature ratings are fully interchangeable between the two standards.
Deflector-to-ceiling
EN 12845 §10.2.5 requires the deflector to be 75–150 mm below a smooth ceiling (versus NFPA 13’s 25–300 mm range). This narrower EN 12845 range is important for installation — a head installed at 200 mm below ceiling may comply with NFPA 13 but not EN 12845. European projects must verify this distance against the tighter EN 12845 limit.
Obstruction rules
EN 12845 §10.2.6 specifies obstruction rules for beams, ducts, and other ceiling obstructions. The standard uses a similar “one-third rule” to NFPA 13 — obstructions deeper than one-third of the distance from the deflector to the ceiling require supplemental heads below the obstruction. The specific dimensions differ from NFPA 13 and must be checked independently for EN 12845 projects.
On spare heads: EN 12845 §17.4 requires a minimum of 6 spare heads for systems up to 500 heads, 12 spare heads for 501–1,000 heads, and 24 spare heads for systems over 1,000 heads — of the same type(s) installed. The correct sprinkler wrench must also be stored with the spares. This is materially identical to NFPA 25 spare head requirements.
5. Water Supply Requirements
EN 12845 Chapter 9 defines water supply categories based on reliability, and Chapter 10 specifies minimum duration requirements. The water supply must deliver the design demand (flow + residual pressure) for the required duration without depletion below the minimum inlet pressure at the riser.
| Hazard Class | Min. Duration | Additional Hose Allowance | Note |
|---|---|---|---|
| LH | 30 minutes | None required | Municipal supply may suffice if flow/pressure confirmed |
| OH1–OH2 | 60 minutes | 2 hose streams @ 250 L/min each | Tank + pump typically required unless exceptional municipal supply |
| OH3–OH4 | 60 minutes | 2 hose streams @ 250 L/min each | Fire pump required; gravity tank as secondary supply recommended |
| HH Cat I–II | 90 minutes | 4 hose streams @ 250 L/min each | Dedicated tank + main pump + standby pump required |
| HH Cat III–IV | 120 minutes | 4 hose streams @ 250 L/min each | Full pump + tank + standby infrastructure; specialist design required |
6. BS EN 12845 vs NFPA 13 — Key Differences
The two standards share the same fundamental engineering basis and arrive at broadly similar system designs for most occupancies. However, there are specific differences that matter in practice, particularly when designing or reviewing a system for a market that accepts one standard but not the other.
| Parameter | BS EN 12845 | NFPA 13 |
|---|---|---|
| Hazard classification | LH / OH1–OH4 / HH Cat I–IV | Light / OH Group 1–2 / Extra Hazard Group 1–2 / Storage |
| K-factor units | Metric: Q (L/min) = K × √P (bar). K=80 standard head | Imperial: Q (gpm) = K × √P (psi). K5.6 standard head |
| Deflector-to-ceiling distance | 75–150 mm (tighter) | 25–300 mm (wider) |
| Max head spacing (OH) | 4.0 m | 4.6 m |
| Max coverage per head (OH) | 12 m² (more restrictive) | 20.9 m² (OH Group 1) |
| Design method | Density/area with fixed design point only | Density/area method or room design method |
| Water supply duration (OH) | 60 minutes + hose allowance | 30–60 minutes depending on occupancy |
| Component certification | CE/UKCA required — EN 12259-1 | UL listing or FM Approval |
| Temperature margin rule | 30°C above max ambient (same) | 30°C above max ambient (same) |
7. Key Clauses Practitioners Need Most
§4
Hazard classifications — Complete tables for occupancy classification including Table 1 (occupancy examples by hazard class) and Annex A (specific storage hazard categories). The most-referenced section of the entire standard.
§9
Water supplies — Classification of water supply types (Type 1: town mains; Type 2: gravity tank; Type 3: suction tank + pump; Type 4: pressure tank), acceptability for each hazard class, and duration requirements. Also §9.7 on duplicate water supplies for HH systems.
§10
Components and installation — Sprinkler head selection (§10.2), deflector positioning (§10.2.5), obstruction rules (§10.2.6), pipe sizing (§10.3), control valve sets (§10.4), and alarm devices (§10.5). The primary installation reference section.
§13
High-rack storage — Requirements for rack storage above 4 m, including in-rack sprinkler requirements, storage category classification (Cat I–IV), and design densities for high-bay warehouse applications.
§17
Maintenance — Inspection frequencies, test requirements, spare head quantities, and record-keeping obligations. Also Annex I (inspection and maintenance schedule forms). The reference section for facility managers and maintenance contractors.
Annex G
Residential and domestic systems — Informative annex covering residential sprinkler system design, equivalent to the NFPA 13D/13R scope. Referenced in UK Building Regulations Approved Document B — Scotland requires sprinklers in all new dwellings above two storeys; Wales requires sprinklers in all new residential buildings.
8. Component Certification & Third-Party Approval
EN 12845 requires that sprinkler heads and components are listed or approved to the relevant EN product standards. The certification framework differs from North America:
CE Marking (EU)
Sprinkler heads for EU markets must carry CE marking under EN 12259-1 declared to the Construction Products Regulation (CPR). CE marking is a manufacturer’s declaration of conformity — not a third-party approval. The CE Declaration of Performance (DoP) must be provided with each product.
UKCA Marking (UK)
Post-Brexit, the UK requires UKCA marking for construction products placed on the UK market. UKCA marking must be supported by UKAS-accredited testing to EN 12259-1. CE-marked products under transitional provisions may still be acceptable — verify current status with the AHJ.
LPCB (UK)
The Loss Prevention Certification Board (LPCB) operated by BRE Global provides third-party product approval under the LPS 1039 scheme for UK sprinkler components. LPCB approval includes factory production control audits and periodic re-testing — many UK insurers and specifiers require LPCB approval rather than merely CE marking.
VdS (Germany)
In Germany and much of continental Europe, VdS Schadenverhütung GmbH certification is the dominant insurance industry approval scheme. VdS-approved components are accepted by most European insurers as satisfying EN 12845 requirements, often with conditions supplementary to the standard minimum.
CA-Fire Products & EN 12845 Compatibility
CA-Fire sprinkler heads are manufactured to GB 5135 (the Chinese national standard, technically aligned with ISO 6182) with NFPA 13 documentation available for export projects. The technical performance of GB 5135 listed heads — K-factors, RTI values, temperature ratings, and activation characteristics — is equivalent to EN 12259-1 listed heads. For projects in jurisdictions that accept products meeting equivalent international standards (many Middle East, Southeast Asia, and African markets referencing EN 12845 without requiring EU CE marking specifically), GB 5135 / NFPA 13 documentation is generally accepted.
For UK projects requiring UKCA / LPCB approval, or projects where the tender specification explicitly requires CE marking, confirm the applicable certification requirement with the AHJ or specifier before ordering. We are happy to advise on documentation packages for specific export markets — contact us with your project requirements.
9. Frequently Asked Questions
Specifying for a European or UK Project?
CA-Fire manufactures the full sprinkler head range from K=80 pendent to K=363 ESFR with NFPA 13 documentation. For projects referencing EN 12845, we can advise on documentation packages and equivalent performance evidence for AHJ submission.
Related Guides & Standards
Authoritative Sources & Standards
- BS EN 12845:2015+A1:2019 — Fixed firefighting systems: Automatic sprinkler systems — BSI Group
- NFPA 13: Standard for the Installation of Sprinkler Systems — National Fire Protection Association
- UL Fire Safety Certification Resources — Underwriters Laboratories
- FM Approvals: Fire Protection Product Certification — FM Global
- LPCB — LPS 1039 Sprinkler Component Approval Scheme — BRE Global