We are in the process of having a ZC fireplace installed (ordered, just not shipped yet). Thought the mantel would be a little easier than what it seems- according to different manufactures sites, clearance from top of fireplace to combustible material ranges from 18" - 23".We are wanting to stick with a surround mantel if possible but based on what I'm getting from it, our surround is going to be huge! Is this normal? I certainly don't want to burn my house down and will work around what we need to do- just wandering if the manufacturers are being a little over cautious. We could certainly do an all rock mantel and solve this riddle but just curious as to what everyone else is doing.