I am gradually replacing my tarmac drive with block paving. The existing sub base is a good 6” thick and seems sound, and there’s been no sinking of the tarmac over however many years it’s been there so I’m keeping the base and removing the couple of inches of tarmac on top.
In some areas of it, whoever layed it put down the blue dpm (looks same as you’d use for a floor slab) between the soil and hardcore. No sand blinding. It’s probably not intact as the hardcore will have punctured it, but am I best drilling a load of holes all over it with a big long SDS to help with drainage? I really don’t want to take the whole lot up, but obviously don’t want to bodge the block paving job. For what it’s worth, I’m laying non permeable pavers, not the permeable stuff.
In some areas of it, whoever layed it put down the blue dpm (looks same as you’d use for a floor slab) between the soil and hardcore. No sand blinding. It’s probably not intact as the hardcore will have punctured it, but am I best drilling a load of holes all over it with a big long SDS to help with drainage? I really don’t want to take the whole lot up, but obviously don’t want to bodge the block paving job. For what it’s worth, I’m laying non permeable pavers, not the permeable stuff.
