When applying the LACoRS guidance to houses converted to self-contained flats (prior to 1991) is the extent of the shared internal communal area irrelevant when counting the number of storeys (section 37)?

For example, a three storey property has only a small communal lobby at ground floor level only with two flat entrance doors located within this lobby. Flat A occupies the ground floor only. Flat B occupies the upper two floors and the stairs are entirely within this flat (technically flat B is over three floors as its entrance is at ground floor level).

As this is a three storey property, then Case Study D11 applies and a Grade A LD2 system (with control panel and call point) is recommended in the (small) common area linked to heat alarms in the entrance/lobby of each flat.

Have I interpreted the guidance this correctly?

Further, if there is a basement/lower ground floor flat in the block (flat C) that has its own separate external entrance and has no access to the communal area, does this flat also require a heat alarm linked to the communal system?

I think so because people on the third floor do not have a window escape available (too high) therefore an enhanced fire alarm is required.  I think it would depend on the separation (60 mins) between the basement flat and the rest and if I was in the basement flat I would want to know if the rest of building was involved in fire.

Hi Tom.  Thanks very much for your response.  I think sometimes people think it seems over the top to have the an alarm panel in such a small communal area, but an occupant still has to travel the same distance to escape from the top floor, irrespective of how much of a communal area they need to pass through.

It could be argued that it is a two storey, flat on ground floor and a maisonette on the first/second floor requiring grade D (interlinked) in the common area with a heat fire alarm in each occupancy, with a grade D in each tenancy not interlinked. But it is all about risk assessment and the guides could be ignored, it depends how concerned you are about the situation.