Leasehold shared loft

[Fishy]

Is this guide stating that cavity barriers are ineffective? Is that a proven fact now?

Cavity barriers are fine... at being cavity barriers, but not as being compartment boundaries.  They don't typically provide the same fire resistance as you would have for the compartment wall (they only require E 30 / EI 15).  They are usually less robust than walls, and are very often hung from the roof construction (rather than being self-supporting) and may be prone to being brought down if there is any collapse of structure on the 'fire' side.

[kurnal]

Funny old world isn't it. Here we are on this thread wringing our hands over roof compartmentation between two top floor flats in a 3 storey block of six flats whilst elsewhere in another thread we are encouraging stay put in a much larger block in which all flats are open to the stairs?

For the record in my earlier posting I was careful to state that I was referring to mineral wool barriers that can give the necessary insulation though I accept have the weaknesses you describe.

[colin todd]

Why is the void not a place to which the Order refers.

[William 29]

Funny old world isn't it. Here we are on this thread wringing our hands over roof compartmentation between two top floor flats in a 3 storey block of six flats whilst elsewhere in another thread we are encouraging stay put in a much larger block in which all flats are open to the stairs?

I don't think that is a fair comparison in terms of the risk Mr K?

[kurnal]

Just my opinion William based on the number of persons potentially at risk and the likelihood of them coming to serious harm in such a small building.