"Peter Taylor" wrote in message
...
Bob Mannix wrote

snip stuff where I am sure you are correct but which differs from my
experience! I am in Vale of the White Horse District Council (Oxfordshire)

I've also never heard of using 2 sheets of plasterboard with a 12mm gap.
In the
above examples, 2 staggered layers of 12.5mm wallboard (without skim) will
give
1 hour FR and 2 layers of 15mm Fireline unskimmed will give 1½ hours FR.

As it happens my brother (same county but different district & planning
area) is in the middle of a loft conversion by a national loft conversion
company - I was there yesterday and could see the construction of part of
the stair wall which had the first layer of plasterboard and then battens to
take the second layer - he told me the rest of the walls were the same.

As an aside, having used Fireline plasterboard myself with no problems
(aside from its weight), I can't understand why anyone would use two layers
of ordinary instead, irrespective of the regs!

Thanks for the reference.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)