From @sbridges2 article seems to cover it well unless you have manufacturer installation instructions.
IS A MASONRY VENEER COVERED WALL CONSIDERED SAFE FOR REDUCED CLEARANCE?
No! National Fire Protection Association (NFPA) codes permit reduced clearances to combustible walls if adequate protection is provided. Sheetrock, sheet metal, masonry veneer and other thin or non-insulating materials placed directly against walls give little protection. These materials conduct heat very well; they will be almost as hot on their back sides as they are on their exposed sides.
Reduced clearances are acceptable for the following:
- an engineered protection system approved by the inspecting authority having jurisdiction
- products and materials listed for protection purposes
- a non-combustible protector mounted an inch or more away from a combustible wall to allow free circulation of air behind it
The reduction is specified by NFPA and most codes. For example, when required clearance with no protection is 36 inches, a 3 1/2-inch-thick masonry wall with ventilated air space used as a wall protector, reduces clearance by maximum of 66 percent, to 12 inches from the combustible wall.