Cavity barriers

[shaunmckeever]

Can anyone let me know what the requirements are regarding cavity barriers.

I have a building with a mix of floors with very large open plan floor spaces and other floors sub-divided by non-fire resisting partitions. In both cases the floor spaces have suspended ceilings with a void depth of approximately 1 metre. Should the voids be divided up every 20m in both cases? This is my interpretation of building regs.

Any help/advice graetfully received

Thanks

[Chris Houston]

I work for a property insurer.  We ask our customers to put fire breaks in that offer 30 minutes (sometimes more) insulation and integrity from fire.

We ask for barriers every 20 metres, or 10 if the cavity has any combustible linings.
We also ask for barriers above fire doors, where there are walkways (or similar) joining buildings, where the barrier goes into stairwells, and anywhere else recommended by Approved Doc B.  I belive our recommendations are very similar to Approved Doc B recommendations.

The Building Regs would recommend what is in Approved Doc B, but that only applies for new builds, refurbs (and maybe change of occupancy, I'm sure others will confirm).  That said, we are all good people and it's not just about complying with the legal minimum is it, it's about best practise and RISK ASSESSMENT!

I would also recommend a third party approved installer, especially for high risk projects.  See http://www.asfp.org.uk/ for more details.

[wee brian]

Chris

How many people actually put in extra cavity barriers at the request of their insurer?

[Chris Houston]

I don't have that information.  I know some customers launched a program of installing them in their entire stock of consortia schools and I expect some completely ignore such recommendations.

Sometimes things like this will be recommended, sometimes they will be required.

[Fishy]

If everything in the void is Class 1 or Class '0' then your interpretation sounds correct (if not, the spacing may need to be reduced to 10m max).  See, however, the exclusions in Table 14 of the ADB.