Start by adding some water to the old stucco surface so it won’t remove water from the new stucco mix. Dip your trowel into the stucco mix, scoop stucco out and sling it onto the surface. By doing this, the stucco should be able to hold onto the mesh. Using a finishing trowel, smooth the stucco mix, and pack it against the existing stucco with a brick trowel. Add more stucco until the layer is about ½ inch thick.