Environmental Impacts of Multi-Storey Buildings Using Different ...

- 35 -4.3.5.2 Floor and RoofThe structural system which supports the flooring has been altered slightly from that of theConcrete building, in order to reduce the maximum span from 12 metres to 9 metres, asshown in Figure 4.8. The upper floors and the roof slabs are timber-concrete composite slabsbuilt using prefabricated structural LVL and plywood decking supported on four internalstructural timber (LVL) gravity beams and the end walls. The plywood decking supports a 60mm thick reinforced concrete composite topping, fixed to the LVL joists by notches andembedded coach screws. The roof slab contains a 75 mm thick fibreglass layer.4.3.5.3 Envelope WallsThe solid, structural LVL envelope walls are designed as coupled rocking walls. They arelocated within the east and west envelope walls, so must be considered as potential thermalbridges. The envelope walls (structural walls or light weight walls) have a 25 mm air cavityfor ventilation under the exterior cladding sheet.4.3.5.4 Internal PartitionsThe light weight envelope walls and the internal partitions are framed in timber studs with 90mm fibreglass insulation and gypsum board internal linings.4.3.5.5 Timber Building FinishesFigure 4.9 shows the north-east and south-west façade perspective view of the Timberbuilding. The north and south curtain walls, external louvres in north façade, roof and plantroom claddings and windows in the east and west façade are the same as in the Concrete andSteel buildings.Figure 4.9: Timber building, North-east and South-west perspective views.The light weight envelope walls in the east, west and south façades (including service areaenvelope walls) are framed in timber studs with 90 mm fibreglass insulation. These wallshave a 25 mm air cavity for ventilation built with 25 mm timber battens under fibre cementsheets used as external cladding. Internal finishes are timber framed walls lined with gypsumboard plasterboard. Acoustic insulation is required between partitions of the main body ofoffices. Generally, a plaster acoustic tiled ceiling is used in all office areas.4.3.5.6 TimberPlus Building FinishesIn the TimberPlus building, all possible ‘common finishes’ of the Timber building werereplaced by timber components in order to maximise the use of wood. Figure 4.10 shows thenorth-east and south-west perspective views of the TimberPlus building.