The short answer: BYKHY defines which buildings need sprinklers and sets the general principles; it leaves how the system is calculated to recognised standards. In practice a project is designed either to NFPA 13 or to EN 12845, and the two are not mixed.
The role of the regulation
The Regulation on Fire Protection of Buildings is the framework instrument for fire safety in Turkey. Its scope is broad: escape routes, fire compartmentation, smoke control, detection and alarm, suppression systems, fire safety management. But engineering detail such as hydraulic calculation, design density tables and sprinkler spacing rules is not inside the regulation.
That is deliberate. The regulation says what is required; the standard says how it is done. The same approach applies in Europe: the national building regulation sets the requirement and EN 12845 provides the calculation.
How the choice is made
Standard selection is not arbitrary; four inputs decide it:
- The expectation of the authority. The standard the approving fire authority is used to is the single biggest factor in how fast approval goes.
- Insurer requirements. International insurers frequently ask for FM Global or NFPA-based design, and that requirement sits on top of the regulation.
- Investor or corporate standard. A multinational manufacturer applies one standard across all its plants, and the Turkish plant follows it.
- The equipment supply chain. The chosen standard brings its own listing and approval requirement. Availability and cost differ between UL/FM listed equipment and LPCB/VdS approved equipment.
The golden rule: one standard, end to end. Taking the design density from EN 12845 and the area of operation from NFPA 13 is an engineering error. The numbers in each standard assume one another; mixed, they produce a system carrying neither one's safety margin.
Practical differences at a glance
| Topic | NFPA 13 | EN 12845 |
|---|---|---|
| Hazard class language | Light / Ordinary 1-2 / Extra 1-2 plus storage | LH / OH1-4 / HHP1-4 / HHS |
| Density unit | mm/min (metric printing) or gpm/ft² | mm/min |
| Water supply duration | By hazard class | By hazard class, with different values |
| Equipment approval | UL / FM listing | EN 12259 series, LPCB / VdS approval |
| Pump standard | NFPA 20 | EN 12845's own pump section |
Can all three coexist?
Yes, but in layers: the regulation sets the mandatory floor, the chosen design standard provides the calculation, and an insurer's FM Global requirement adds a further layer of protection. In that case the design follows the most restrictive requirement, and the design report states explicitly which decision came from which document.
What the design report must state
- The chosen standard and edition year (for example "NFPA 13, 2025 edition").
- The hazard classification and its justification.
- Design density and area of operation, with the table reference in the standard.
- Water supply duration and the volume calculation.
- Any insurer or investor requirements and which decisions they changed.
- The equipment approval scheme (UL/FM or LPCB/VdS).
Those are the six headings asked about most at review; a report written around them from the start shortens approval noticeably.
Frequently Asked Questions
Does BYKHY contain the sprinkler calculation?
No. The regulation defines which buildings need sprinklers and sets general principles; hydraulic calculation, design density and spacing rules are left to recognised standards such as NFPA 13 or EN 12845.
Can NFPA 13 and EN 12845 be mixed?
No. The numbers in each standard assume one another. Taking the density from one and the area of operation from the other produces a system carrying neither one's safety margin.
Does an insurer requirement replace the regulation?
No, it sits on top of it. The regulation is the mandatory floor; an insurer requirement such as FM Global is an additional layer. The design follows the most restrictive requirement.
What decides the choice of standard?
The expectation of the approving authority, insurer requirements, the investor or corporate standard, and the equipment supply chain — assessed together.
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Download MEP Calc on the App StoreThe Turkish Regulation on Fire Protection of Buildings (BYKHY) · NFPA 13 (2025) · NFPA 20 (2025) · BS EN 12845:2015+A1:2019 · FM Global Data Sheets. For article numbers and numerical limits, the current regulation text published in the Official Gazette governs.