The invention relates to a slab for a raised technical floor, comprising a core with a lower surface and an upper surface each covered with a metal sheet provided with rims that partially cover the edges of the core. The core has a sandwich structure in which the lower layer is a non-combustible heat-insulation layer containing cellular glass and having a low heat conductivity and a low density, while the upper layer is a non-combustible carrier panel containing cement or silico-limestones reinforced with fibres and having good bending and compression resistance. The slab is relatively light but still exhibits good characteristics in terms of bearing capacity and fire resistance.