Disclosed is an apparatus and a method for at least partially encapsulating a fiber batt or other substrate by applying a polymer fiber layer to one or more surfaces of the fiber batt or substrate by melt-blowing. The melt-blowing assemblies are arranged and configured to extrude both a polymer melt and a hot gas stream whereby the hot gas stream attenuates the polymer melt to form polymer melt fibers and to direct the polymer melt fibers toward a surface to be coated. The melt-blowing assemblies are further of the fiber batt. A combination of melt-blowing assemblies may be provided in either fixed or moveable configurations for coating one or more sides of the fiber batt.