Fire detection system needed - or - redundant system?

[Brandon]

Afternoon

My query to you learned chaps is this....

We are a Social Landlord and have been 'gifted' a 5 storey residential block of flats (Built 1972) that is partly connected to a large Church (circa 200 years old). Originally the Church managed and ran the whole site until they wished to move out of the Residential side. The flats have two protected exits from each storey, with strict access arrangements - the main egress and access route (front door) and an alternative stair that descends into the Church lobby (which is protected) and access out. This cannot be used as an access by the Residential Customers into the residential side as the church is locked from outside and secure with restricted /locked doors from the church side into each of the storey exits.) So escape can only be done from the flats through the church exit.

The compartmentation between properties is sufficient for a 'stay put'. Residential side is a purpose built block of 15 flats, well maintained, staff on site Mon-Fri, with no areas of weakness. (An intrusive survey was carried out) Any adjoining parts with the Church have adequate separation of concrete ceilings/floors and brick and block work walls throughout. The basement areas of both buildings are solid and well compartmented to a minimum of 1 hour, in line with the rest of the buildings construction. Any fire within each side would not affect the stability of the building or place anyone at risk within the safety of their flat - or progress further than the compartment / origin of fire.

At some point (15 years ago) a decision was made to install an alarm system within the residential part with a BS 5839 part 1 system to L4 covering the common areas/stairs only by smoke detection, sounders and mcp's (each flat is covered by a BS 5839 part 6 linked to a Warden Control System). Due to the change in ownership, no documents are available on why this was installed.

The only connection between the two buildings is the sterile alternative exit (never used by the Residential side) that is connected via the alternative protected stair via compliant, well maintained fire doors and self closer from each storey exit and leading to the sterile church lobby via a second compliant well maintained fire door and ultimately the church car park.

Both fire doors offering a minimum total of 60 mins separation and having the additional separation of a sterile concrete stair between purpose groups, class O walls and no ignition source or combustibles.

So, the question I propose is,
Would you remove the L4 system from the Residential side as this is currently not providing any safety benefit?

A fire would not occur in the common areas and each flat is well compartmented with a reasonable detection system in place and warden controlled. If the communal system activated this could drag the residents out of the safety of their flat into a possible risk area (a fire is not likely to happen, sterile, no ignition sources, well maintained and staffed Mon-Fri)

A fire within the church (huge open plan areas, limited combustibles, concrete and robust compartmentation throughout) would be contained and would not spread to the residential flats. (note ? the Church has been advised to conduct a FRA as one was not available at the time)

Or replace the aged system and interlink within the Church?

Thanks for reading this far....

[Brandon]

Ooops.
error on my part reading my notes - The alternative escape does not discharge into the church lobby but its own double door exit to outside. (there is a locked fire door to the church lobby - access is restricted)
apologies.

[John Webb]

I am very cautious about having smoke detectors in a church - most churches use candles at some time or another and can be a cause of false alarms. With adequate fire separation between the two sections of the building, a common alarm system or links between systems in each part is probably best avoided if the Fire Risk Assessment for each part agrees.

[AnthonyB]

If the fire alarm is linked to a Warden call system it smacks of Sheltered Housing - a totally different ball game regarding fire warning systems compared to general needs flats. Who are the residents?

You also make no mention of the smoke control facilities expected in a block of this size for stay put.

[William 29]

From what you have described the fire alarm in the common areas of the flats has potentially been useless anyway? From experience of dealing with similar circumstances for several large housing groups these "common" alarms are just installed with no thought or risk based approach. If the reason was to provide a full evacuation strategy this would unlikely be achieved if the common alarm does not extend into the flats, either by a heat detector or at least sounders to provide 75dB at the bedhead. 

The fire risk assessment should be able to confirm if the alarm is needed but from what you have provided I would think it is not required?