Part 1 vs Part 6

[North London]

I have just completed a loft conversion and need to install fire precautions. My property is a second floor flat and I have just added a third floor.

The council have advised that I have I must comply with either of the following:

1. BS5839 Part 1 L3

or

2. BS5839 Part 6 Grade D LD1

Which they have said means detectors in escape routes and risk rooms (which they say is every room in the house except bath rooms) suitably interlinked.

This effectively means a very costly system given the grade and number of detectors(8 in total).

My understanding is that I really should only need detectors in the Kitchen and then on each landing/entrance (hence 3 in total)

Are they trying it on?

[kurnal]

It sounds as though the building has been divided into several separate dwelling units and is being treated as a house in multiple occupation. If this is the case they are applying the correct standard.