BS 5839-1 or BS 5839-6 for mixed-use building?

[Guest Gherkin]

Hi.

We have a building that has been converted from offices and shops into retail/commercial on the ground floor and residential units above. The building has not been converted in accordance with Building Regs. The Fire Risk Assessment has recommended a BS 5839-1 system in the common areas to the residential and commercial, linked to detection in the commercial units and hallways to the flats.

A fire alarm installer is disagreeing with this (without having visited site). He is saying it should he BS 5839-6 (and citing P.55 of the Fire Risk Assessment in Sleeping Accommodation guidance book). Please advise whether part 1 or part 6 is correct. I would have thought it was part 1 as it's not a wholly residential building.  Please provide reasoning/a reference for your advice. Thanks.

[AnthonyB]

The installer is not the risk assessor - try another one if they are being difficult, they should design to the specification provided. It's semantics really as even if Part 6 it would be a Grade A system that essentially uses the same equipment as a part 1 system.

Part 6 cannot provide a suitable system design for the commercial areas whereas a Part 1 system can incorporate sleeping accommodation as well as commercial so Part 1 would suit the project.

The guidance is just that - guidance - not prescriptive otherwise there would be no need for a risk assessment and it would not be unreasonable for this scenario to use Part 1

[Guest Gherkin]

Thank you for your help Anthony. Much appreciated. 

[NickCSL]

Would a fire alarm system in an office block converted into flats and operating an evacuation fire strategy (linked to heat detectors within flats) need to be Part 1 or Part 6? There are no commercial units. 

The Safelincs summary of Part 6 says the communal parts of blocks of flats are outside the scope of Part 6, which suggests the system would need to be Part 1. Or should converted offices (and other commercial units) be treated in the same was as converted houses (which are within the scope of Part 6). Guidance I've found on this seems to be quite vague/contradictory.

[AnthonyB]

The guidance is vague because the expectation is a post 1991 conversion from commercial to residential would be to Approved Document B with Building Regs approval and a stay put policy so no common alarm.

In the real world some conversions do have to use a fire engineered approach outside of Approved Document B & operate an evacuate policy with common alarm and these are usually based around Part 1 of BS5839 as they often borrow from ADB volume 2 (which includes residential other and commercial sleeping risk)

The Lacors guide which uses Grade A Part 6 systems for conversions into flats is intended primarily for houses converted into flats as these are often traditionally under the radar of local authority Housing Officers as lead enforcers and can be HMO's for s257 of the Housing Act and be liable for licensing if an authority desires under additional licensing if less than 2/3 owner occupied.