Extensive Fire Cavity Barriers requirements / compensation

[Paul1979]

Hi All,

We have a commercial building that has a roof space which is measured in length to be 37m. It has no cavity barriers at all so when you pop your head up in the space you can see the full length of the top floor. It is 1700mm deep so its fairly big. Its not used for any storage and is accessed via a few hatches fitted in the ceilings. The compartment walls do not extend through to the roof void space either.

The landlord is saying that their previous FRA showed this was acceptable due to the ceilings being plasterboard throughout, and also having smoke detection in the voids.

The building is 5 years old (finished just before Grenfell) and is used for Residential Care Home purposes. No sprinklers.

I have read ADB Vol 2 and it appears to show extensive voids should be separated every 20m? But I am not very good at reading / understanding the various means of when this doesn't need to apply so wondered if someone could explain this in simple terms please??

As always, any help / guidance is truly appreciated.

[Alexis]

Bump

[witsd]

Regarding 'the ceilings are plasterboard' 60 minutes or 30?

If 60, then you have a pretty good compartmentation between a fire in a flat passing into the loft cavity and then back into another flat - probably as good as the flat doors would offer, so from a fire risk assessment point of view, I might well accept this (whether it meets the legal requirement at time of building or not).

If it's only rated for 30 minutes, I don't think I would accept that reasoning - 60 minutes between flats is simply not good enough in a residential care home.

Regarding the smoke detection within the area: I assume there's a common area alarm system with separate (maybe some controlled crossover?) systems in each flat - is the loft directly linked into this, and how are alarms responded to? ARC link, or 24 hour staff presence?

[Paul1979]

Hmmm...it looks like the ceilings are standard 12.5mm plasterboard to me...no sign of any pink stuff! So guessing that is just 30mins?

The AFD in the loft is linked to the buildings fire alarm system (addressable). Each of the residents bedrooms have AFD (smoke) heads. It is a M/L1 system according to the commissioning certificate issued by fire alarm engineers who installed it back in 2017.

Building Control would have surely been involved and signed this off too? But we cannot find the fire strategy (if there ever was one)...so we're second guessing. We will probably involve a fire engineer to complete a strategy for us anyway.

[Messy]

I am sorry I am late to the party but I have been a bit busy. In any case, I don't think I can help much.

I too find B3 of Approved doc B almost unreadable at times. The constant referring to different section and in some cases different standards not deterred in ADB makes it difficult to comprehend - a fact raised a few times in the Grenfell Inquiry

My first question is where the hell is the Regulation 38 information? This is a requirement for the developer to provide fire safety information to the Responsible Person. For a residential care setting, I would argue it is essential to see this before any FRA or fire safety strategy is written

The building is 5 years old so the documents should be traceable - but if often the case, the information does not exist, the Responsible Person should kick some backsides to get it from the developer/builder.

The whole evacuation strategy relies on knowing what compartmentation is in place. Actually for a new build, it should be the other way around. The escape strategy should have dictated the design. But with no Regulation 38 information, its not easy to establish.

My reading of ADB is that a 30 min ceiling means that no sub division is necessary (see diagram 9.3 on P78). I would need to read it a few times to be sure, and I would have to understand whether ‘stay put’ or ‘Progressive Horizontal Evacuation’ systems are in place as they may require additional compartmentation.

How about entry into the roof space? Are the hatches fire resistant? Are the points where services enter the roof void fire resisting…. 5 years on? For example, where lighting cables or recessed lighting is fitted (hoods).

I appreciate that extensive fire detection is in place, including in the void. But is that enough? OK staff will know about the fire quickly enough, but will there be enough of them to do much about it at 3am with minimum staffing levels?

There is also a part of ADB that say residential care buildings should have compartment floors and Table B3 on P141 suggests that compartment floors should be 60 Min fire resisting. Wouldn’t the ceiling between a bedroom and roof void be a compartment floor? I think it would

Sorry my reply is a bit disjointed but blame my grandson who kept me up last night!!

In summary,
I would query where the Reg 38 information is
Assess the suitability of the evacuation strategy to the compartmentation
Question whether this ceiling is a compartment floor therefore 60 mins fire resistant
Check the hatches and service penetrations through the ceiling are fire resistant