SA/cold applied BUR gravel system,,UL Class A

Can anyone give me short-cut to a UL tested SA membrane/emulsion, cold applied, gravel assembly?

I've typically come up with our own spec on residential projects that customers insist on a gravel roof..However, now I have a mmunicipality that's requesting UL Class A fire rating compliance.

I've got the feelers out to a couple of manuf's...Just hoping someone may have something off the top of their heads?

Can't help, but interested. I would assume you'd have to apply over a complete FR system, including FR cap sheet, though, and consider the gravel a coating. Here, I doubt we could get past Title 24 reflective req. for commercial.