: SYSTEM T WALLS AND CEILINGS   System T Standard Panel Specification.   System T ceilings and walls are constructed with a metal stud system faced with 12.5mm plasterboard. The metal studs are extended to the underside of the ceiling and are normally secured to the host building ceiling slab and walls.   12.5mm tapered plasterboard is fitted to each face, with taped joints and coved corners. External faces are finished with board finish plaster, prior to application of the final finish.   Insulation   Walls: Rockwool infill slabs or rolls sealed within the wall construction to avoid any seepage of fibres.   Ceilings: Rockwool which can be encased with sealed PVC bags to avoid migration of fibres to the surrounding area.