A template assembly for use in the production of a variable depth building wall surface, which may be simulative of multiple units separated by mortar joints, such as a simulated brick, stone, tile, or mosaic surface. The template assembly is formed of a backing sheet which is releasably attached to a substrate formed of nonwoven spunbond polyester material, which may be fiberglass reinforced. The substrate is a unitary sheet having a plurality of upwardly extending strips connected by a plurality of sidewardly extending strips. The strips define a plurality of openings within which simulated building units may be formed. A first layer is applied to a wall surface, the template backing is removed and the template adhered to the first layer, and then a second layer is applied over the template. When the template is removed, those areas corresponding to the template strips will be recessed from the second layer.