bids are invited for primary hanging framework - providing lightweight metal framework from gi aluminium ms sections suspended from primary isolated framework using neoprene isolation washers resilient clips. no rigid connection to rcc slab or masonry walls. complete with all fixings. , high-density cementitious board layer 1 - providing 12mm thick high-density cementitious fibre board conforming to is standards fixed to isolated gi framework using corrosion-resistant self-drilling screws. boards with staggered joints and tight butt joints. all perimeter interfaces sealed with non-hardening acoustic sealant. , limp mass acoustic barrier layer - providing 5mm thick high surface density flexible acoustic membrane limp-mass type having material density 1900 to 2000 kg per cubic meter and minimum surface density 9.5 kg per square meter. membrane laid with minimum 50mm overlap at joints bonded using flexible acoustic adhesive with all overlaps fully sealed. , high-density cementitious board layer 2 - providing 12mm thick high-density cementitious fibre board conforming to is standards fixed to isolated gi framework using corrosion-resistant self-drilling screws. boards with staggered joints. all perimeter interfaces sealed with acoustic sealant. , 50mm channel cavity with absorptive infill - providing 50mm deep gi channel framework forming absorptive cavity infilled with 50mm thick high-density mineral wool insulation rockwool type with minimum density 98 kg per cubic meter. cut accurately and friction-fitted between channels ensuring full contact without gaps or compression. , wood fibre acoustic wall panels outer - providing magnesite-bonded pine wood fibre acoustic wall panels surface painted with kerfed long edges. panel size 600 by 1200 by 20mm with minimum density 400 kg per cubic meter. green-certified and low-voc compliant. fixed on concealed gi framing system with polymer h-spline jointing achieving minimum nrc 0.70 and saa 0.70. , secondary hanging framework -