Steel Buildings in Europe

Part 8: Building Envelope 8 - 20 specify acoustic requirements to reduce noise break-out from within a building (for example if the building is sited adjacent to a residential area). Cladding system manufacturers will be able to provide acoustic performance data for different constructions, and be able to recommend a system to meet the specification. A built-up system comprising an inner and outer sheet of pre-finished steel with mineral wool insulation generally achieves over 40 dB of sound reduction. Rock mineral wool has a greater density than glass mineral wool, and generally improves the sound insulation. Sound insulation can be improved by including a layer of dense acoustic mineral wool slab, in addition to the insulation quilt. In general, factory insulated foam filled composite systems are not as effective as built up systems, because of the low mass of the foam core and the direct coupling of the inner and outer skins. The sound reduction index R w for various systems is shown in Table 3.3. A higher index indicates higher sound reduction. Table 3.3 Sound reduction index for typical cladding systems Cladding type Sound reduction index R w Built-up system – with rock wool and acoustic insulation 47 built-up system with rock wool 45 built-up system with glass mineral wool 41 composite panel with mineral wool 31 composite panel with foam 25 single skin 24 3.5.5 Further information Further guidance is available in MCRMA Technical paper No. 8 Acoustic design guide for metal roof and wall cladding [8] and also from ECCS-TC7 Publication 41 Good practice in steel cladding and roofing [6] . 3.6 Fire performance In general, any concerns about the reaction of cladding to fire are far outweighed by concerns about the smoke and gas generated by the contents of the building, not the envelope. Single sheet cladding is considered to contribute significantly to any fire. Single sheet cladding is generally assumed not to make any contribution to fire resistance, although in practice some integrity and resistance will be provided. Single skin sheeting is generally not used on boundaries, when prevention of fire spread to neighbouring structures is important. Built-up systems that use mineral wool or glass wool insulation are not considered to contribute significantly to any fire. Built-up systems may also be