T.0 Struc Unbound Granular Fill material is recommended for use where the fill material will be subject to substantial loading and /or dynamic loading, or the depth of fill is greater than 900 mm to the top of the subsoil.
T.1 Struc 0/31.5 Unbound Granular Fill (Crushed Rock) or 0/40mm Gravel is recommended for use where the overall depth of fill to subsoil is less than 900mm.
T.2 Perm 4/40mm Gas Permeable Layer is recommended in any building where a Radon Sump is to be operational in the sub-floor including all occupied new build projects, i.e. anywhere a person might be for work, leisure or residence.
T.3 Blind 0/4mm Blinding Layer is used when blinding the top surface of the T.2 Permeable material to ensure the radon barrier is not punctured and there is a level surface upon which to place the insulation and pour the concrete.