The Brew Cabin

Posted: **Wed Apr 29, 2020 4:33 pm**

Hi all,

I am planning a gravel drive and would like some guidance / clarity on the prep.

The size is approx 70sqm and currently is a mix of soil, ballast, hardcore, concrete, sand etc etc. basically it has been used to stand everything required for an extension and new rear garden.

Plan:

- Mini digger to dig down past all organic material to a solid sub grade

- 150mm hardcore compacted to around 100mm

- Setts to form barrier and entrance

- 50mm deep gravel (20mm gravel)

Now on reading this forum I have some concerns:

My drive slopes towards my house very very slightly over approx 7 meters. Will a type 1 sub base be permeable enough?

Is a geotextile required between sub grade and sub base ?

And should I invest in a gravel grid system to minimise gravel movement, and if so I believe I will then require a 20mm layer of sharp sand on top of the type 1 to allow the grid to sit nicely on base

Any advice is greatly appreciated, and or any criticism for that matter.

Thank you

👍🏼

Posted: **Thu Apr 30, 2020 6:55 am**

You said you were using 150mm hardcore as a sub base, not mot, so that should drain ok, depending on what the sub grade is like.
Look to see what the sub grade is like if its quite soft, then use terram, but otherwise on a gravel drive, it's not essential .
Dont waste your money on those plastic grids, they are designed as for minimal excavation site, above tree roots etc.

Posted: **Thu Apr 30, 2020 12:21 pm**

Type 1 isn't completely permeable, but it's usually permeable enough to permit drainage of an overlying gtavel dressing.

A geo-textile can't do any harm, but make sure it is a proper construction grade geo-textile and not some rips-like-tissue landscape fabric

Grid systems are fine for stability and minimising migration, but only you can decide whether the additional cost is worth it on your project. It can't hurt to call, say, Simon at GroundTrax in Harrogate (03456 800 008) and get a price on their CellPave 40 product which is ideal for driveways.

Finally - 50mm gravel depth? That's verging on a gravel trap, rather than a surface dressing! 30-35mm is plenty with a 20mm aggregate.

The Brew Cabin

Gravel driveway - prep clarification - Prep