Large gravel driveway

[htb]

6 hours ago, aspenarb said:

If the drive thats there is of sound make up I would scarify and roll what's there., then top off/roll with the bare minimum of dressing. Nothing worse than driving through a sea of stone and it never stays where its put. We use a guy that has what looks like a mini mulcher on a small sit on machine that planes off existing dressings, makes very easy work of relaying existing build ups. I will dig out a pic of his machine.

 

Bob

One of the sites I look after for the Gas Board, there was a issue with contamination so decided to top dress the gravel surface, they wanted 70mm of gravel on top of existing. Unfortunately the contractor used was asked to put 70cm of gravel on top, they used water worked gravel as well, its like quicksand there now, drive on there at your peril. The mistake was noticed at the time but at least 30cm was put on.

[doobin]

2 hours ago, htb said:

One of the sites I look after for the Gas Board, there was a issue with contamination so decided to top dress the gravel surface, they wanted 70mm of gravel on top of existing. Unfortunately the contractor used was asked to put 70cm of gravel on top, they used water worked gravel as well, its like quicksand there now, drive on there at your peril. The mistake was noticed at the time but at least 30cm was put on.

What sort of contractor worth their salt wouldn't query such a work order before starting work?

[Conor Wright]

What sort of contractor worth their salt wouldn't query such a work order before starting work?

One that's making a good profit on the gravel!

[Dan Maynard]

Then charge for taking all the excess gravel away as well. Good job.

[Guest Gimlet]

IMO and from all my experience in the building trade, 50 mm of shingle is far too deep for a driveway. Car tyres will sink into it and it'll wash around all over the place. 25 mm is plenty.

The secret to loose gravel driveways is a perfectly even and perfectly flat subsurface.

If there's the slightest slope the shingle will constantly migrate to the lowest point, and if it's uneven it will show with flooded hollows and bare high spots. 

 

Cellular matting greatly reduces the tendency for migration and produces a far more stable and long-lasting result where the subsurface is imperfect. But it only really looks good from a distance. Close up it's very utilitarian and looks like a beach-front car park. And on a drive that size, it's expensive. And retro fitting it means lifting what you've got, adjusting the substrate to maintain levels, and starting again. An even when fitted correctly it won't hide an uneven surface, in fact it'll emphasise it.

 

I'd be asking why the existing driveway needs renewing. If it's washing around, or there's bare spots, no amount of new gravel will make any difference and will just be throwing good money after bad. If the ground is naturally uneven or sloping beyond what can be remedied with cellular matting, resin bonded is the only option for a durable gravel look, otherwise forget it and go for fixed paving or tarmac. 

 

If it is pretty flat but has become rutted or weedy and tired looking, then it can be renovated but it will require either making good or complete relaying of the compacted subsurface, not adding to or replacing the shingle. Muddiness indicates barrier matting was omitted, has failed, weed membrane was used in error or there is a drainage problem - any of which means stripping back to bare earth and starting again. It's not a case of just topping up the shingle or replacing soiled muddy shingle with clean because the new stuff will go the same way as the old in very short order.

Basically, it's the base that needs the attention, not the shingle, otherwise the client is wasting her money on a short-term fix.

Edited June 14, 2020 by Gimlet

[Gardener Joe]

Agree that any top dressing of gravel needs to be as shallow as possible... only need to cover the sub-base to leave an attractive finish. Patching dips and troughs only works if the new base material is blended to loosened existing.... remember compact compact compact!!! ?

[donnk]

grading beam were invented for this. 

 

 

[Stere]

I wonder if could use  some type of trommel screen then could reuse existing gravel instead of buying  80 tonnes of new gravel?

 

 

Edited June 15, 2020 by Stere

[Stere]

I wonder if could  use some type of trommel screen then could reuse existing gravel instead of buying  80 tonnes of new gravel?

 

 

[Guest Gimlet]

80 T of new washed shingle is going to cost up to 3.5 grand just to supply. If you can wash/clean and recover the existing for less than that including labour it certainly makes sense.

 

Thinking about it, you wonder why the original builder just quoted for more shingle, when it's the base that needs the attention. Was he just going to throw more down in top of old?