This invention relates to an improved insulation system for covering a facade of a building consisting of at least one insulation element, at least one mechanical fastener, which fastener fixes the insulation element to the facade of the building, whereby the insulation element has at least a first and a second layer, the first layer being directed to the facade having a bulk density being lower than the bulk density of the second layer, whereby at least one layer is made of mineral fibers, especially stone wool fibers and a binding agent and whereby the fastener has a shaft erecting through the insulation element into the building and a plug-plate being arranged on or in the outer surface of the insulation element.To achieve an insulation system which has very good insulation characteristics, which can be produced for low costs and which can be fixed to the facade of a building without causing high labor costs the shaft if the fastener partly erects into the first layer of the insulation element in a direction parallel to the surface of the facade.