Son recently bought a house that lady had lived in for 50+ years, floor covered in lino and carpet, sign of dampness under lino but nothing that would cause major concerns. Original floor was quarry tiles on clinker backfill. Have dugout floor to 100mm depth and concreted with dpm sheet beneath. Cheap and cheerful as his plan is to rent it out in the future so not to fussed about insulation. 80 year managed without it or any central heating for 50 years. House built 1910 or so.