Abstract: A method and apparatus for spraying on a desired surface, such as a wall, ceiling, or the like, an insulating coating comprising a mixture of a flowable dry fibrous material and a liquid adhesive, very thoroughly wetting the dry material, the latter comprising cellulose fibers (as opposed to mineral fibers) together with various additives. The wet mixture is sprayed on the desired surface at such a velocity that a substantially uniform insulating coating is produced requiring no subsequent tamping, the coating being uniform as to density, consistency, appearance, and the like. The cellulosic fibers are derived from ground paper, such as bleached sulfate paper, or unbleached newspaper, kraft paper, or the like, mixed with various additives to provide the finished insulating layer with fire and rot resisting qualities, to color same, and the like.