EN 12845-1 Annex N — The CMSA Informative Annex

Annex N is the informative annex to EN 12845-1 — the first European standard reference for CMSA design. Even though EN 12845-2:2024 is now the primary reference, Annex N remains useful as the description of record for systems already installed.

At a tyre warehouse, a CMSA system was installed in 2018 under an Annex N reference, since EN 12845-2 did not yet exist. After 2024 the insurer's annual audit added a note to "assess migration to EN 12845-2". The system was compatible with the existing hardware, so only the documentation was reissued. A backward-compatibility assessment is usually the practical route for Annex N projects; the whole system rarely needs replacing.

Annex N history

• 2003: Annex N published in the first edition of EN 12845
• 2009: Updated, with an expanded commodity list
• 2015+A1:2019: The current edition
• 2024: EN 12845-2 published, leaving Annex N dormant
• It still exists as an informative annex

What Annex N covers

1. Definition of CMSA (Control Mode Specific Application)
2. Typical commodity list (Class III–IV, tyres, paper, plastics)
3. Recommended K-factors (K115–K200)
4. Table of design sprinkler operating numbers
5. Placement rules (spacing, deflector position)
6. Basics of in-rack coordination
7. Water demand determination
8. Listing requirements
9. Maintenance methods

Typical Annex N commodity table

Commodity	Storage height	K-factor	Pressure	Design heads
Class III standard	≤ 7.6 m	K160	2.4 bar	15
Class IV timber	≤ 6 m	K160	3.0 bar	15
Tyres on tread	≤ 6 m	K200	3.5 bar	20
Paper rolls on end	≤ 8 m	K200	3.0 bar	15
Group A plastics on pallets	≤ 6 m	K200	3.5 bar	20
Idle timber pallets	≤ 6 m	K160	3.0 bar	15

Annex N versus EN 12845-2

Aspect	Annex N (12845-1)	EN 12845-2
Status	Informative	Normative
K-factor range	K115–K200	K115–K480
Commodity detail	Summary table	Extensive list
ESFR	Not covered	Covered in its own annex
In-rack detail	Basic	Detailed
Listing	General	Specific
CE marking	Limited	Full support

Field error — an old Annex N design with a new commodity

A Class IV warehouse installed a CMSA system to Annex N in 2019 at 6 m storage height. In 2025 the commodity changed and Group A plastics on pallets were introduced. The Annex N table calls for K200 with 20 design heads for Group A plastics at 6 m; the reference was updated, but the manufacturer's listing did not cover the new commodity. The system was upgraded to a currently listed product referenced to EN 12845-2. On older Annex N projects, a change of commodity is the trigger — the listing match must be re-checked.

Four migration scenarios

1. Existing system: documentation reissued against EN 12845-2, hardware unchanged
2. Existing plus extension: only the new part is designed to EN 12845-2, compatible with the Annex N base
3. New project: EN 12845-2 is mandatory, Annex N is not referenced
4. Mixed: offices to OH under 12845-1, storage to CMSA under 12845-2

Alternative references to Annex N

• NFPA 13, CMSA chapter — comparable level of detail
• FM Global Data Sheet 2-0 — approved product listings
• VdS CEA 4001 — the German CMSA reference
• LPCB rules — UK CMSA design
• ISO 6182-7 — sprinkler product standards

Insurer positions in 2026

• FM Global: EN 12845-2 required on new projects
• VdS: EN 12845-2 plus VdS-specific testing
• LPCB: EN 12845-2 as the main reference
• International insurers operating in Turkey: EN 12845-2 for new work, Annex N accepted for existing systems
• Domestic insurers: BYKHY plus EN 12845 is generally sufficient

Turkish regulation and local practice

BYKHY does not distinguish between Annex N and EN 12845-2; it simply refers to EN 12845. TS EN 12845-2:2024 has been published and is the official reference. Existing Annex N installations typically receive a migration recommendation after their annual audit, while new projects from 2026 onwards should reference EN 12845-2.

Quick check list

• Which standard was the existing system installed to — Annex N or EN 12845-2?
• Has the stored commodity changed in the last five years?
• Listing match is current.
• New projects reference EN 12845-2.
• In a mixed building, offices to 12845-1 and storage to 12845-2.
• Insurer preference documented.
• CE marking carried out under EN 12845-2.

Frequently Asked Questions

Is Annex N still valid?

It remains published as an informative annex to EN 12845-1, but EN 12845-2:2024 is the normative reference for CMSA and ESFR. New projects should be designed to EN 12845-2.

Does an existing Annex N system have to be replaced?

Usually not. In most cases the hardware remains compatible and only the documentation is reissued against EN 12845-2. A full upgrade is triggered by a change of commodity, not by the standard alone.

What K-factor range does Annex N cover?

K115 to K200. EN 12845-2 extends this considerably, up to K480, and adds the ESFR provisions that Annex N never contained.

What triggers a re-assessment of an Annex N design?

A change in the stored commodity is the main trigger — particularly a move into Group A plastics or tyres. The manufacturer's listing must be re-checked against the new commodity.

SprinkCalc — Fire Sprinkler Design Across Three Standards

SprinkCalc covers hazard classification, design density and area, K-factor selection, water demand and hydraulic calculations for NFPA 13, FM Global and BS EN 12845 in a single iOS app, and exports a professional PDF report.

Download SprinkCalc on the App Store

MEP Calc — 86+ Engineering Calculators

MEP Calc bundles 86+ engineering modules in one iOS app: 21 fire calculations plus heating, cooling, HVAC, plumbing, steam and natural gas.

Download MEP Calc on the App Store