I think of the materials that are in common use cement board would be one of the most stable in terms of expanding and contracting. I would suspect the problem is from expansion or contraction of the wood frame supporting the cement board. Framing wood shrinks an incredible amount in a frame home, mostly occurring in the first year of occupancy. If this shrinking is not accounted for lots of problems can and do occur. If it is installed over a block wall, block shrinks a tremendous amount as it ages as well.

I used cultured stone just once at the insistance of the contractor that we designed the home for. In that instance we provided a brick ledge for it. Even though it is only 2" thick, there is a lot of weight there and I am not comfortable with hanging it off a frame wall because of the movement in wood structures responding to moisture and temperatures and because of the aformentioned shrinking.

I tend to go with traditional stone veneer with a generous concrete ledge to sit it on. It is not much more expensive than the cultured products.

If you like the cultured product I suggest using a real brick ledge made of reinforced, concrete not depending on hanging it off the frame wall.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.