Raised garden area where patio was

Good evening all. Long term reader. First time posting. I hope everyone is well and apologies if I'm not posting correctly.

I'm renovating my garden , and need more green space.the photos attached are of a raised patio, 400 mm off other ground level. The area is 40 m2 , but I will be extending that by another 40. Under the slabs is hard-core and crushed brick etc.the area is retained with breeze blocks, which I will remove and reenforce with oak sleepers.

I'm wanting to change this area into turf/garden area. Will I need to remove all the hard-core/rubble? Or would if be possible to remove some and create the turfed area on top ?

Any advice would be appreciated.

Thanks

John

 

Hello! You reaĺly need to remove as much rubble and hardcore as humanly possible. Then break up any hard, compacted layer of soil. Replace to the level required with decent topsoil. Doing the job thoroughly now will save lots of time, money and frustration further down the line

 

It looks like a big job to me, yes you will need to remove all the hardcore and probably import a fair amount of top soil.

 

Thanks all. Would you recommend just using topsoil , or maybe some subsoil for stability ?

 

I presume you have your own subsoil beneath the hardcore.

 

The deeper the topsoil, the healthier the grass will be...

 

Ha, yeah I'm hoping so. I just didn't know if 400mm maybe more of top would be ok ?

 

Ah brilliant thanks a lot

 

400 is enough for grass