none mechanical - heat recovering mechanical - non recovering none radiators underfloor Pre-1900 1900-1929 1930-1949 1950-1966 1967-1975 1976-1982 1983-1990 1991-1995 1996-2002 2003-2006 Post-2006 Not applicable Normal More Than Typical Less Than Typical Much More Than Typical Much Less Than Typical Not Defined external filled cavity internal as built unknown None 12mm 25mm 50mm 75mm 100mm 150mm 200mm 250mm 300mm+ unknown Not Defined Rafters Joists No Access Not Defined none mains service private dual Single Unknown 12mm 25 mm 38 mm 50 mm 80 mm 120mm 160mm None Foam Jacket No Access No Cylinder Normal - between 90 and 130 litres Medium - between 131 and 170 litres Large - greater than 170 litres. Dual Single A SAP Heating Code is a code specified in the RD/SAP specificationto identify characteristics of the heating system. They are numerical codes selected from a standard list detailed in the specification. Codes indicating average height of a room, storey or building part 1 storey 1.5 storey 2 storey 2.5 storey 3 storey no corridor heated corridor unheated corridor Lower ground Ground 1st 2nd 3rd 4th Roof space Detached Semi-Detached End-Terrace Mid-Terrace Enclosed End-Terrace Enclosed Mid-Terrace Main Property 1st Extension 2nd Extension open flue balanced flue window roof-window database SAP Table exposed floor semi-exposed upper floor to unheated space semi-exposed upper floor to partially heated space Other flat below Ground floor