Tarmac Toplite Standard Foundation Blocks 3.6N 440 x 215 x 300mm are produced specifically for use below DPC to replace the inner and outer leaf, wall ties and concrete fill associated with traditional build methods. They help to achieve lower U-values in ground floors as it provides a degree of vertical perimeter insulation. It also lowers the heat loss from thermal bridging and gives better ‘psi’ values in energy calculations.