Fireplace Hearth

I nearly messed-up the fireplace base. Over the weekend I was reading the section in the Building Code of Australia on heating devices. Of course, the fireplace has to be built on a masonry base - but so does the hearth immediately in front of this. The hearth must extend at least 300mm in front of the fireplace, and extend at least 150mm either side. I had forgotten that the hearth also needed a masonry support, so over the weekend I mixed up some mortar and laid extra bricks to support it (fortunately the fireplace footing was large enough to support these extra bricks.