Comprised of a Celcon thin joint untied separating wall with a 75mm cavity filled with Isover acoustic insulation, finished with plasterboard on dabs. No render/parge coat on the wall surface was considered necessary with this design. This was aimed at meeting a minimum acoustic performance of 50dB DnTw + Ctr, 5dB above that required by the building regulations, to attract 3 credits under the Code for Sustainable Homes (CfSH). Airborne sound tests undertaken on the properties resulted in performance value of 55-57dB, which in fact is even better than the highest possible credits achievable under the CfSH of 4 credits, where a minimum value of 53dB is required. These are the highest sound reduction test results we have ever achieved.