In blocks of flats (top floor flats) with flat roofs - where it is not feasible to access the small roof voids on the top floor due to no available access hatch, how do we determine the presence of insulation in the first instance without some form of intrusive inspection and damaging people’s homes/ ceilings? We cannot report correctly to allow an adequate design at present. To ensure a complete building ‘fabric wrap’ this void space would need insulating but may not offer the possibilities to do so internally, leaving only external flat roof insulation which will add to the project costs considerably