I have a timber framed 4 storey block of flats.

Issues with compartmentation which is confirmed. Went into the roof void which the wall that seperates the protected corridor and flat does not extend into the roof void & into the eaves. 

Present silent L4 in the communal for Aovs. LD3 in flats to support stay put.

I have asked for SD in the roof space connected to the communal system and an interlinked Heat detector past the flat front door to alert residents to a fire in the roof and for change to simultaneous untill we get the compartmentation resolved. Also to not we can not confirm yet if the compartmentation is sound in the communal corridors. 
Inside the flat a is LD3. I have asked this be brought up to the present standard LD2.

Fire alarm Engineer has agreed apart from he wants additional heat detectors as part of the communal system in all the rooms to support simultaneous.

I feel this isnt required a I would be happy one Heat detection in the circulation space linked to the communal system so to alert them to a fire in the roof void or communal area.
 

Your proposal is the usual installation in these situations, however different buildings will require more. If there is a risk of spread from rooms to external structure or rooms to floor above that are greater than they should be in a correctly built block then the provision to all rooms may be appropriate.
You know where the issues lay, you specify the cover required based on that.

Thanks Anthony,

maybe the additional heat would cover us until we do a type 4 to explore the true extent of the compartmentation. Better to be safe.