Joined: July 2004
||Posted: 20 Feb. 2019,10:14
Regarding those 50mm layers, the *real* reason behiond that advice is that far too many installers lack the correct equipment to thoroughly compact a single layer 100mm sub-base. They use lightweight, cheap vibrating plates that don't meet the requirement of the relevant British Standard, be it part 3 or part 4.
So, instead of insisting installers invest in the right equipment, which would cost perhaps another 300-500 quid for a piece of kit that should last at least a decade, this ineffective "workaround" is proposed, despite the fact that the maximum particle size of a Type 1 granular material, at 37.5mm, renders it practically impossible to construct a sound sub-base of only 50mm depth - as explained here
There are sound engineering reasons behind the requiirements set out in the British Standards, and those reasons are so well-considered and widely recognised that they are "emulated" by equivalent standrads in so many otrher countries with temperate climates. They are *that* good.
So, when someone with a fraction of the knowledge and experience that put together the original standards comes up with what is little more than a 'bodge', I prefer to disregard it and attempt to educate anyone that will listen a sto *why* it's a bodge, and *why* those of us that stick to Standards do things the way we do.
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