Spray Lath is a West Coast product, where stucco is spray applied to the surface of the lath to build up the stucco thickness. Kraft paper is factory applied to prevent over spray of stucco. The spaces between the strips of Kraft paper allow for the visual alignment of the sheet for mechanical attachment of the ribs to the substrate. Rib Lath is often attached directly to the vertical framing members without a solid board substrate included.