Digging Lawn for Permeable Driveway, How Deep?

Hi Folks,

Digging my small front garden up to put in an extra parking spot. Just wondering how deep should I dig?

I am now 20cm down below the height of the tarmac for the existing parking spot.

I havent hit any rock yet, however would that be a sufficent depth to now fill in with stone before putting the top with either tarmac or some other permeable surface?

On the permeable surface, whats the best material to finish off the top for the parking spot, is tarmac the handiest?

DOCARCH

Usually for a driveway 225mm deep compacted hardcore substrate.

Gravel is usually the cheapest permeable surface. Regular/standard tarmac is not permeable but there is such a thing as permeable tarmac.

How deep does the gravel or tarmac have to be on top then? If you use gravel, do you also have to compact this?

Mellor

https://www.boards.ie/discussion/2058231453/digging-lawn-for-permeable-driveway-how-deep

225mm hardcore for the base, plus the topping.

What is your permeable topping? Standard tarmac isn't permeable (nor is it tarmac for that matter). You cold do gravel, but would want to consider how it looks next to existing driveway.

listermint

804 for the base . Depths as above. And top up with 50-70mm of colour stone of your choice. Look for tonne bags from nearby supplier.

DOCARCH

Usually gravel layer is 40/50mm thick installed on layer of compacted quarry dust over the hardcore.

Not sure about overall depth of tarmac but usually around 50mm thick with base layer and top layer.