Fire Compartmentation of Services Risers with Concrete Floors and Ceilings

[Rex]

Where there is a communal services riser in a block of flats, but the riser is fire-stopped at each floor (i.e. there is a concrete floor and ceiling on each level) - is it necessary to have a compartment wall that faces into the flat? I've looked through Approved Document B but I can't find a satisfactory answer. In this scenario, would the whole floor be a compartment rather than the riser itself - or would the riser still have to be a compartment?

[AnthonyB]

What is in it? Electrical distribution cupboards, whilst not compartments per se, are generally enclosed in fire resisting enclosure to protect adjoining areas.
Each flat has to be a compartment so unless it was part of the flat (i.e. containing only the flats distribution board and accessed from a door in the flat) you would expect the wall facing the flat to be a compartment wall.

[Rex]

On 14/10/2024 at 21:46, AnthonyB said:

What is in it? Electrical distribution cupboards, whilst not compartments per se, are generally enclosed in fire resisting enclosure to protect adjoining areas.
Each flat has to be a compartment so unless it was part of the flat (i.e. containing only the flats distribution board and accessed from a door in the flat) you would expect the wall facing the flat to be a compartment wall.

Hi thanks for your response! The riser has water pipes and drainage stacks that benefit each flat in the HRB. I'm doing a BSR application and so need to detail compliance with Part B of the Building Regulations for a bathroom refurbishment - there is an existing access panel to this riser which is not fire rated because the block of flats was built in the 1960s (and the previous asbestos panel has been replaced with an mdf panel). The 'riser' is fire-stopped at each level though, and so only the pipes pass through the concrete floor. So I am not sure whether the access panel needs to be fire compartmented in the first place as it might not count as a 'riser' given it has a concrete floor and ceiling (with only pipes passing through). 

Both APD B and the Fire Safety in Purpose Built Flats guide don't seem to help with this specific scenario.

[AnthonyB]

If the original panel was asbestos this will have been the original fire rated enclosure - a 1960's block would indeed have compartmentation (see CP3 Chapter IV Part 1) and if this has been altered worse then original it needs remediation - however if it is now stopped at each floor you could potentially argue that this has been used as an alternative approach to remediation that provides the same level of protection.

This should be determined as part of fire risk assessment, retrospective fire strategy and the safety case.