We are going to be adding a new gas fireplace to our family room. We are going to be adding the fireplace to a 17 foot wide wall (with 8 foot ceilings), with built-ins on either side. The fireplace will have a ledge stone surround with a mantel. The fireplace we have chosen has a visible glass area of 31" wide by 28" high (we are not doing any decorative fronts or doors).

The look we want is similar to the picture below.

Typically, what are the dimensions of the stone/tile surround?

I'm sure there's an article out there somewhere on this with standard ranges, but I can't seem to find it!

Thanks in advance for any help.