Stone surround help

[Arhuranna]

Starting work on my first fireplace and am looking for tutorials on building a raised stone hearth. I have salvaged enough limestone form an old house for the base but need advice on how to start. My plan after framing is to attach hardie board to my subfloor then mortar the stone block to that. Advice would be great. I've included a pic of the stone home we're salvaging.

 

[begreen]

Can you tell us more about the project? Maybe shoot us a picture of the fireplace location.Is this just a hearth extension or the full fireplace? A full fireplace will need a better base than a subfloor. It will need a full masonry support structure with a substantial base foundation to carry the weight.

(broken link removed to https://brick.com/scratch-built-masonry-fireplaces)