Final answer:
A factory-built fireplace is generally less expensive to install than a masonry fireplace, due to lower labor costs and the potential for integrating cost-saving heating devices.
Step-by-step explanation:
The phrase to fill in the blank in the sentence 'A factory-built fireplace is _____ expensive to install than a masonry fireplace' would be 'less' to correctly compare the installation costs of the two fireplace types.
A factory-built fireplace, also known as a prefabricated or pre-built fireplace, is generally designed for easy installation, which usually makes them less expensive to install compared to their masonry counterparts.
Masonry fireplaces, built with bricks, stones, or other masonry materials, often require a more labor-intensive process including constructing the firebox, a chimney, and often a foundation to support the structure. This can make masonry fireplaces significantly more expensive in terms of materials and labor costs.
Additionally, factory-built fireplaces are designed to integrate with wood stoves or other efficient heating devices that prevent most of the heat from escaping through the chimney, which can contribute to cost savings in the long run.