It's a seismic thing. Your building code should speak to it. The problem is that without physical attachment to structure, the stone veneer wall will shake off during an earthquake, raining deadly missiles down on people.
Out here in a seismic Zone 4, we used expanded metal lath that was screwed to structure with screws and washers against the lath. When the scratchcoat is put on, the screws and lath become embedded, providing solid fixation. Apparently the bond between the scratchcoat and the veneer is adequate, but I did note that when the veneer went higher than 8 feet, the mason also embedded brick ties, also screwed to structure, that became part of the veneer layer as the stone was set.
Be aware that code thinks about stone veneer differently when the weight per square foot goes over a certain amount. So, regular stone veneer might get one treatment while thin stone veneer might not require the same.
We also used a brillo pad type roll product that went up against the ICF or the wood sheathing and provides an air space behind the scratchcoat. |