I'm wanting to install a wall heat shield as easily and cost effective as possible. I know NFPA allows a 1/2" noncombustible cement board with 1" spacers, but my question is whether I can install 5/16 exterior fiber cement lap siding or panel over top the cement board for aesthetic purposes. The technical specs on Allura fiber cement siding state it is noncombustible and Type A fire rated. Just checking if anyone has used the product before. Thanks!