Laying Patio over Tarmac

My rear yard is completely tarmac’d over as was when bought, it’s about 8m long x 5m wide, I’m on a hill so it slants right to left down and away from the house. It’s the only outside space for the house so I want to get it somewhere near usable, and level.

The slant away from the house is not as much as the left to right so to stick within planning they’ll be a step somewhere in the middle of the left and right so that height increase stays below 300mm.

I’ve dug the higher side of the yard up by stripping up the top layer of tarmac which is 40mm deep, under that theres about another 40mm of tarmac sub base, and under that a good few inches of hard core.

Am I ok to level up directly on the tarmac sub-base with hardcore? then patio on top? Or do I need to dig the tarmac sub base out? I’m hoping it’s the first.

The drops about 200mm at the highest point so I’m planning on a small retaining wall with flat blocks around the perimeter of the levels.

Besides that, anyone want rid of owt?

When I say level I mean outer line on the bubble to allow water run off

Similarish problem, except I’m looking to patio over a concrete garage base and an old patio (that’s on top of another patio)

everyone will say you need to remove it all and prepare a new sub base.  You can’t guarantee the strength of the old stuff etc….

in my case digging out will be tonnes and tonnes of concrete, so I figure it’s cheaper to lay on top and if there is a problem with a section, it’ll be far cheaper to dig it out and repair.

if you dig some test pits and it the base looks in good condition and decent depth I’d go for it

I dug some fence holes, the concrete was nearly a foot thick in places, no way I’m taking all that out, it’s not going to be subsiding due to a few slabs on top

I’m thinking the same tbh, the rest of the house was done on the cheap by the last owners but it looks someone’s done this to a decent standard, with the top layer up it’s now pourous so should be ok, just need the hardcore to adhere to it.

I’ve heard people putting hardcore straight onto the tarmac which seems bonkers.

It’s only taking very light foot traffic, the cars going in another area so I’m hoping should be fine.

Surely the tarmac sub base is the same as patio sub base would be?

Standard patio is 100mm hardcore ‘I think’ need to double check paving expert.

What I have is 40mm’ish tarmac sub base, then the hardcore under that.

In my experience an old sub base that has had years to settle and compact is absolutely fine for putting new flags on. Whatever you’re laying on, if it’s strong and subsidence free then I’d be disturbing it as little as possible.

As above, old sub base will be very settled, so level it as best you can !

Ditto

We had similar here. We’ve just pavioured straight on top of the concrete. Drains nicely away from the house unless the gulleys get blocked, so I keep on top of that as a matter of course. It’s only ever any kind of problem in the autumn when the leaves fall. We get a lot of leaves so I have to be vigilant.