I was wondering what you think about insulating under a block and beam floor. Building control specifies approx 200mm ventilated gap under a suspended block and beam floor. I am quite unsure of why this is. Apart from expanding of clay floor underneath, I can't quite see a reason (with suspended timber, it would be air circulation, but for block and beam?) Would it be possible to fill the space underneath with insulation. For example perlite, or some other no moisture/rot sensitive material