Hi. I have an old finca in Spain with a pitched concrete roof waterproofed with aluminium backed asfalt. I want to insulate it with 6cm extruded polystyrene foam sheets and then lay interlocking terracota tiles on top. Is this a reasonable option, are there specific types of polystyrene insulation intended for this type of use.
I realise this is not a common problem in the UK but if anyone has an opinion I would be grateful for any advice.
