A method for coating a support with a lightweight insulating shotcrete, includes preparing the shotcrete by mixing, in predetermined proportions, at least a fibrous aggregate, a binder and water; pouring the prepared shotcrete in a tank; having at least one outlet; continuously moving the wet shotcrete in the tank until it reaches the or each outlet; sucking the wet shotcrete along a feeding pipe linking the outlet of the tank to a spraying gun, with a Venturi hose fed with pressurized air, included in the spraying gun; spraying the sucked shotcrete on the support with the spraying gun.