3150 Composite concrete floor system (9) 3151 Composite construction of in situ concrete and permanent formwork (14) Flooring systems with permanent formwork, structural or non-structural, topped with in situ concrete 3152 Composite construction of in situ and precast concrete (9) Composite construction of in situ and precast concrete, forming the frame, walls, slabs, columns, trusses of the building fabric 3153 Tilt-up, lift slab and other composite constructions (3) Tilt-up, lift slab and similar constructions where precast units to form walls and floors are attached to a pre-erected structural frame or are interconnected 3154 Post-tensioning concrete construction (0) Post-tensioning of in situ concrete, precast assemblies and composite construction of in situ and precast concrete 3155 Concrete raft floor system (8) Raft floor system using preformed permanent pod formwork to form a concrete waffle raft floor slab-on-ground.