I have to make up ground level for a courtyard garden to allow proper cover for drains, etc. I have a great pile of clay muck, could I use that or should I buy crushed stone hardcore. The area is low and can be wet. Intention is to have hard surface, brick or pamments, etc.
The trouble with using clay to build up level is that it's a bugger to compact thoroughly, so use sub-base material. Building-up with clay is ok if youpre going for dsoil cover, but for hard paving, I'd recommend sub-base material every time.