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Posted: Thu Dec 12, 2019 12:05 pm
by RoryL
Hi,
I'm looking to get my driveway paved with omega blocks so I'm getting quotes.
All of them talk about a layer of type 1, then a layer of sand, with the blocks laid on top.
But some recommend a thin layer of lean mix between the type 1 and the sand, to stop the sand washing down. Others say that's a bad idea as it would stop water draining away as it's supposed to.
So far it's about 50/50 from the tradesman I've had in to quote, which leaves me confused.
Lean mix, or no lean mix??
Thanks
Posted: Thu Dec 12, 2019 12:47 pm
by Tony McC
If in doubt, rely on the British Standard - Oh! No mention of a lean mix layer, most commonly used to cover the fact that some contractors lack the competence to construct a sound and functional flexible/unbound sub-base.
If a base is used which is what that lean mix would actually be) then a whole new situation arises and provision for adequate drainage of the laying course has to be implemented, all of which whacks up the costs....unless it's missed out and the contractor relies on being long gone by the time the client realises the mess they've been left with.
There are projects where a bound base (lean mix or similar) are waranted. Only 2 or 3 times in 40-odd years have I seen such a case with a residential driveway. It's for Category 1 and Category 2 pavements - freight yards, ports, adoptable highways, not for driveways!
Posted: Thu Dec 12, 2019 1:28 pm
by RoryL
Tony McC wrote:If in doubt, rely on the British Standard - Oh! No mention of a lean mix layer, most commonly used to cover the fact that some contractors lack the competence to construct a sound and functional flexible/unbound sub-base.
If a base is used which is what that lean mix would actually be) then a whole new situation arises and provision for adequate drainage of the laying course has to be implemented, all of which whacks up the costs....unless it's missed out and the contractor relies on being long gone by the time the client realises the mess they've been left with.
There are projects where a bound base (lean mix or similar) are waranted. Only 2 or 3 times in 40-odd years have I seen such a case with a residential driveway. It's for Category 1 and Category 2 pavements - freight yards, ports, adoptable highways, not for driveways!
Ok, thanks for the info Tony. I'm happy because the contractor I'm leaning toward is anti lean mix.
Thanks again.