5 Blocks of 2 storey flats built in 1965, with a mixture of 2 & 4 flats/block, have front doors and entrance hallways complying with Building Regulations then in force. 

QUESTION: Must these front doors be updated to FD30s fire doors, or will hallway smoke alarms provide adequate fire safety?

I cannot give a definitive  answer without seeing the full layout, but no, a hallway smoke alarms will not provide adequate fire safety and all front doors need to be updated to FDs fire doors.

Thanks Tom. The flat front doors are demised as part of the flat, therefore, the flat owner would have to bear the cost of around £1,500 per flat. Unfortunately, some tenants cannot afford this!

Is there a time limit on uprating flat doors to comply with FD30s?

I suggest you read the guidance here https://www.local.gov.uk/sites/default/files/documents/fire-safety-purpose-built-04b.pdf

This will allow you to assess what improvements may be needed and also that smoke alarms in the hallways are not required and of no real value

The government publication 'Fire safety in purpose-built blocks of flats', Section 23.3, page 31, states 'It is wholly inappropriate to impose the current guidance for new blocks of flats retrospectively to existing buildings. Nevertheless, current guidance can be considered when setting benchmarks against which to assess the adequacy of fire protection within existing blocks of flats'.

Question: if there is no need to upgrade flat front doors to FD30s will smoke alarms in the common hallways improve fire safety

Further to my response above I would suggest you have the front doors assessed to see what needs to be done to achieve the required standard, http://fdis.co.uk/ may be able to help. 

No, smoke alarms in the common space have no value other than to confuse residents as to the evacuation strategy and potentially cause them to leave the safety of their flats into a danger area (which has had fatal consequences). We generally have them removed.

Detection (without alarm) is only required where needed to operate an automatic smoke control system.

They are also inadequate where a full evacuation policy is needed.

It was the local fire brigade that recommended installing smoke alarms in the common hallways! Without fire alarms how will residents know there is a fire in the hallway or neighbouring flat? I understand the need for immediate evacuation if there are no FD32s fire doors but I don’t know how the alarm will be raised?

Local crews aren't often trained in fire safety beyond the basics, specialist departments in the FB do this.

If it is a stay put block you don't need to know about a common area fire as the worst thing you can do is leave your home as several people have paid for with their lives. As these areas generally contain minimal combustibles you are safer in your 60 minute 'box' as it will eventually burn out or be extinguished.

If it's a stay put block you don't need to know about a fire in another flat as that will be contained within it's own 60 minute box and whilst there may be some smoke leakage into the corridor that only means it's safer still to stay where you are.

If it's full evacuate you need a proper fire alarm system with detection linked to a central control panel which covers the common areas and (as a minimum) the flat internal lobbies, with call points in the common areas and alarm sounders in the common areas and (as a minimum) the flat internal lobbies as the flats are not 60 minute boxes and you need to know about the fire before it breaks out into the common areas and to adjoining flats. 

Thanks Anthony,

Now I have a good understanding of the arguments I need to present to Tenants in order to persuade them to upgrade their front doors: either they have a significant increase in their Service Charge to pay for  proper fire-alarm system with ‘immediate evacuation’ or pay for a new FD30s front door and ‘stay put’.

Final Question: In a block of 4 Flats (2-story), the tenants have elected to have a fire-alarm system for the common hallway, with 'immediate evacuation policy'.  Then an invalid in an upper floor flat has an FD30s front door fitted, will he/she be able to 'stay put' in the event of a common hallway fire-alarm?

If you are in the common hallway and it's on fire (which it shouldn't be short of an aggressive arson attack using a lot of accelerant) you would evacuate, but if the block meets structural requirements it should be safe to stay put in your flat if needed.