What is the difference between a masonry fireplace and a factory built fireplace?
Masonry built fireplaces are built by a mason using bricks and stones.This type of fireplace requires a foundation to support the weight of all the materials.
A factory built (also called a pre-fab or zero clearance) fireplace is a fireplace which consists of a metal firebox with a metal flue and chimney cap. The weight of this metal system allows a fireplace to be installed without a foundation.