Clearance around the fireplace opening

[Shak00]

Hi,
We removed a cast stone facing from our 42 inch fireplace model WRT2042 (superior fireplace) and now redesigning it to a modern look with tiles around the opening and plain white wooden facing (as in the target picture). There is some confusion about how much area around the fireplace opening must be noncombustible. From the design (second picture) you will notice that we are doing 8 inches of tiles all around the opening and then 10 inches of wood facing above the opening and on each side. Is 8 inches of noncombustible material (tiles in this case) sufficient? I checked the specs and installation instructions but couldn't fine any reference to these clearances. Will appreciate some feedback.
Thanks,
Shak.

 

[begreen]

That looks ok. This is what popped up online.

 

[Shak00]

Hello bgreen,
Thank you for answering the query. Mantel is 6 inches wide an 8 or 10 inches deep floating shelf instead of angular one as shown in the diagram. Do we need to move it up in that case? In the picture, mantle clearance with 33 deg is my concern. Our mantel starts at 18 inches but then extend 8-10 inches. Also which part of the diagram indicates the side clearance.
Appreciate your help!
regards,
Shak