A coating system comprising: (1) a liquid intumescent coating composition comprising a resin system comprising at least one polymeric component, at least one ethylenically unsaturated monomeric component, and at least one intumescent ingredient, the coating composition being curable to a solid state by free radical polymerisation, and (2) a reinforcement structure. The reinforcement structure may comprise any of mesh, fabric and/or tape. The reinforcement structure preferably comprises an inorganic fabric, and may be installed by application of a suitable adhesive binder.