What’s the difference between a BS 5839-6 and a BS 5839-1 fire alarm certificate?

BS 5839-6 covers a single domestic dwelling and uses a combined Grade-and-Category classification. BS 5839-1 covers commercial and industrial premises and uses Categories L1–L5, P1–P2 or M, typically across a fuller design/installation/commissioning document set rather than one combined form.

What are Grades A, C, D1, D2, F1 and F2?

They are the six current domestic fire alarm grades under BS 5839-6:2019+A1:2020, broadly describing the system’s power supply and control arrangement. Grades B and E existed in earlier editions and were removed by the 2019+A1:2020 amendment — a current domestic certificate should not use them.

Do flats need a BS 5839-6 or a BS 5839-1 certificate?

Both can apply on the same building: individual flats are typically assessed under BS 5839-6, while communal areas such as corridors, stairwells and lobbies are typically assessed under BS 5839-1, since they function as shared, managed space rather than a private dwelling.

What does Category M mean?

Category M, under BS 5839-1, is a manual fire alarm system — call points and sounders, with no automatic fire detection. It’s one of the classification options for a non-domestic system, alongside the L (life protection) and P (property protection) categories.

Is BAFE SP203-1 required to install a commercial fire alarm system?

It isn’t a universal legal requirement, but it’s a commonly used third-party certification scheme for BS 5839-1 work, and many clients and insurers look for it as evidence of a competently installed and maintained system.

Does a house extension need BS 5839-1 because it’s a bigger job?

No — which standard applies depends on the type of premises, not the size of the system. A domestic extension is still part of a single dwelling, so it stays under BS 5839-6.

UK electrical certificates explained

Fire alarm certificates and BS 5839: domestic vs non-domestic explained

A fire alarm certificate for a single home is assessed against BS 5839-6, recording a Grade and an LD or PD Category; for any other premises it is assessed against BS 5839-1, using L, P or M Categories. This guide explains what each standard asks for and how to tell which one applies.

Last updated 15 October 2026. Written by the CertSync team and checked against the standards.

The short answer

A fire alarm certificate for a single domestic dwelling is assessed against BS 5839-6:2019+A1:2020, recording a Grade (A, C, D1, D2, F1 or F2) and a Category (LD1–LD3 for life protection, PD1–PD2 for property protection). A fire alarm certificate for a commercial or industrial premises is assessed against BS 5839-1:2025, using Categories L1–L5 (life protection), P1–P2 (property protection) or M (manual system, no automatic detection). The two standards don’t overlap — a single dwelling is never assessed against BS 5839-1, and a commercial premises is never assessed against BS 5839-6.

Domestic vs non-domestic — the split that decides everything

BS 5839-6:2019+A1:2020 covers fire detection and alarm systems in a single domestic dwelling. BS 5839-1:2025 covers commercial and industrial premises — offices, shops, factories, warehouses and non-domestic buildings generally. Which standard applies is decided by the type of premises, not the size or complexity of the system, so a large house extension still sits under BS 5839-6, and a small commercial unit still sits under BS 5839-1.

A block of flats can split across both standards depending on the area: individual flats are typically assessed under BS 5839-6, while common parts — corridors, stairwells, communal lobbies — are typically assessed under BS 5839-1, since those areas function as shared, managed space rather than a private dwelling.

Domestic systems — Grade and Category (BS 5839-6)

A domestic fire alarm certificate under BS 5839-6:2019+A1:2020 records two separate classifications together. The Grade — A, C, D1, D2, F1 or F2 — broadly describes the system’s power supply and control arrangement, in outline ranging from the most robust systems down to simpler standalone detectors. Grades B and E, which appeared in earlier editions of BS 5839-6, were removed by the 2019+A1:2020 amendment and should not appear on a current certificate.

The Category — LD1, LD2 or LD3 for life protection, or PD1 or PD2 for property protection — describes which parts of the dwelling the system covers, broadly ranging from whole-property coverage down to escape-route-only protection. A domestic certificate records both figures together, since Grade and Category answer different questions: what kind of system is fitted, and where it covers.

Non-domestic systems — Categories L, P and M (BS 5839-1)

A non-domestic fire alarm certificate under BS 5839-1:2025 uses a different classification: Categories L1 to L5 for life protection, P1 or P2 for property protection, or M for a manual system — call points and sounders, with no automatic fire detection. Which specific category applies to a given building is determined by a fire risk assessment rather than a fixed rule, and the certificate records the category assessed against.

BS 5839-1 work also typically involves a fuller document set than the domestic single certificate — separate design, installation, commissioning and handover records, rather than one combined form.

Third-party certification — BAFE SP203-1

Commercial fire alarm work to BS 5839-1 commonly involves BAFE SP203-1 third-party certification, an independently audited scheme covering design, installation, commissioning and maintenance. It is an industry-recognised route rather than a universal legal requirement — the same principle that applies to competent-person schemes for general electrical work.

Frequently asked questions

What’s the difference between a BS 5839-6 and a BS 5839-1 fire alarm certificate?: BS 5839-6 covers a single domestic dwelling and uses a combined Grade-and-Category classification. BS 5839-1 covers commercial and industrial premises and uses Categories L1–L5, P1–P2 or M, typically across a fuller design/installation/commissioning document set rather than one combined form.
What are Grades A, C, D1, D2, F1 and F2?: They are the six current domestic fire alarm grades under BS 5839-6:2019+A1:2020, broadly describing the system’s power supply and control arrangement. Grades B and E existed in earlier editions and were removed by the 2019+A1:2020 amendment — a current domestic certificate should not use them.
Do flats need a BS 5839-6 or a BS 5839-1 certificate?: Both can apply on the same building: individual flats are typically assessed under BS 5839-6, while communal areas such as corridors, stairwells and lobbies are typically assessed under BS 5839-1, since they function as shared, managed space rather than a private dwelling.
What does Category M mean?: Category M, under BS 5839-1, is a manual fire alarm system — call points and sounders, with no automatic fire detection. It’s one of the classification options for a non-domestic system, alongside the L (life protection) and P (property protection) categories.
Is BAFE SP203-1 required to install a commercial fire alarm system?: It isn’t a universal legal requirement, but it’s a commonly used third-party certification scheme for BS 5839-1 work, and many clients and insurers look for it as evidence of a competently installed and maintained system.
Does a house extension need BS 5839-1 because it’s a bigger job?: No — which standard applies depends on the type of premises, not the size of the system. A domestic extension is still part of a single dwelling, so it stays under BS 5839-6.

Disclaimer

This guide is general information, not professional advice, and does not replace professional judgement, training, scheme-body guidance or the current editions of BS 5839-6 and BS 5839-1. CertSync does not verify the qualifications of the people using it. The contractor named on a certificate is responsible for what it certifies.

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