Driveway: membrane between type 3 and tarmac ?

[bmj1]

Buildup:

London Clay

Membrane

200mm type 3

80mm permeable tarmac

20mm permeable resin bound gravel 

 

Do I want/need a membrane between the type 3 and the tarmac to stop the tarmac pouring through the holes of the type 3? Or is tarmac thick enough that this isn't an issue ?

[Oz07]

Wouldn't of thought so myself but could be wrong never used permeble. I have seen a driveway done with it and it looked terrible after a few years all loose stones everywhere like an old knackered carpark. It could of been down to a bad job or lots of dry turning though?

[nod]

You don’t need a membrane Most weeds are seeded It’s unlikely that anything will cum up from clay