Cavity Barrier requirement

[Guest JDR]

Hi, 

After a fire stopping survey was undertaken in the care home i work for, the fire stopping company advised that a fire barrier was required in the roof space as it is over 20m (im waiting for confirmation as to by how far in excess of 20m) . When i referred this to the Fire Risk Assessor, they did not see a need for this to completed on the basis we have detection in the roof space (unused), fire-rated ceilings below and on the basis it is a relatively new building and the design and construction was subject to building control approval at that time (2016) and had been accepted as is. This hasnt been picked up as an issue in any previous fire risk assessments which we have had completed every year (same assessor for the last 3 years, a different company prior to this). 

Given the difference of opinions, i would appreciate some additional expert guidance please as it is quite a large cost. 

[Mike North]

Roof spaces should be divided every 20m, if it is slightly over, I would accept. 

Building control from 2016 means nothing

[AnthonyB]

One of the many defects that contributed to the multiple fatalities at the Rosepark Care Home fire was inadequate separation in the roof void. In a roof void cavity barrier's should be installed directly in line with any compartment walls below, but if the ceiling is fire rated the cavity barrier's are not required to be inline with the walls below and are used to reduce the roof space to maximum 20m in length - but they are still provided. The issue is that a fire rated ceiling is normally only tested from below for fire resistance and not from above, so a fire in a roof void could compromise the ceiling in less than the required time of fire resistance. Fires have also spread externally into roof voids via window & wall cavities and from windows by passing the suspended ceiling. A Building Control approval doesn't mean that much as there are so many buildings passed despite latent defects. Being 2016 it should be to current standards as they were in place back then as well. 
The risk assessors have failed to take into account that it's a Care Home - if it was an office or similar with simultaneous evacuation there may be a case for risk based evacuation based on AFD alone, but for a sleeping risk premises with vulnerable occupiers requiring assistance to evacuate and likely to be operating progressive horizontal evacuation it is critical that the highest level of compartmentation is maintained as it's not going to have a 3 minute evacuation time!