A nozzle assembly for conveying a flow of particles of insulation material suspended in air to a substrate to form an insulation product on the substrate is provided, including: a nozzle body defining a flow path for accommodating the flow of particles of insulation material suspended in air, wherein the nozzle body comprises an inlet for receiving the flow of particles of insulation material suspended in air; an outlet for propelling the flow from the nozzle assembly; and at least one expansion section in which the cross-sectional area of the nozzle body expands in the direction of flow, the at least one expansion section being effective to reduce the velocity of the particles flowing therethrough; and at least one binder outlet for providing a binder to the flow of particles of insulation material propelled from the outlet.