After the compressing of the hardcore, a layer of sand was laid to stop the hardcore puncturing the insulation and damp proof membrane. 
We laid 80mm of polysterene insulation and a damp proof membrane before embarking on the pouring of the concrete slab.
As always wanting to achieve as much as we could without heavy machinery, we poured to concrete by hand...well four hands, one cement mixer and 3 and a half days of hard labour!!! We were knackered but over the moon to have the slab done.
