I have to adhere cultured stone to the perimeter foundation of the house I’m building. I plan to double-paper over the plywood shear walls, staple on expanded metal lath, and trowel on a coat of mortar for a substrate before the “stone” is applied. I expect I’ll also have to trowel mortar on to the concrete back a couple feet where the concrete stops and plywood shear walls begin to avoid an abrupt step-out line. How thick should the mortar be on the expanded lath over the plywood, and what sort of fastenings should hold the lath to the plywood?