Concrete flag bedding thickness - Bedding thickness

[cw76]

Hi All

I've been going through the main site pages and from information I have myself on what thickness the laying course bed should be for concrete flags.
for rigid:
On your site it says 20-40mm.
In the BS its 15-25mm compacted.
Interpave 25mm conpacted.
for Flex:
on your page its 40mm.
In the BS its 25mm compacted (and to rake the top 10mm for ease of laying).
Interpave its 25mm compacted.

Which thickness should I be specifing?
Thanks

[Rich H]

What kind of paving and what's the application?

[cw76]

Its a general query I've no job in specific, but its Concrete Flags either 50 or 65mm thick. And I'd mostly used flags in pedestrian areas but sometimes with the 65mm with occasional trafficing overrun. does that clarify my query?
Any suggestions?
Does it make much of a difference in the laying course thickness in relation to the depth of flag and the application of the flags being used??
And I know the laying course should never be used to introduce falls, but can you explain why?
I know one reason, is that you would have a thicker bed at one side and a shallower at the other, but how could this cause the pavement to fail?
Thanks

[lutonlagerlout]

the strength is in the sub base and sub grade,the laying course is just that,a final course to level up the flags
ideally the laying course is as thin as is workable which in practise is around 35-50 mm (for me anyway)
any thinner and you run the risk of cracking flags
any thicker and the bedding course may fail
LLL