Betts Fireplace and Chimney Project, Day 4

The liner is not bonded within the structural masonry elements of the fireplace.  This is to say that, should the fire box begin to decay,  it can be removed and replaced without damaging the integrity of the system over and over again for hundreds of years.  But this is one of many approaches to building fireplaces.  Formal fireplaces may call for split firebrick laid on a herringbone pattern within the firebox.  There are a range of options, but I have a particular fondness for building with the oval, clay brick, basket weave.