Cracked panels and worn fireplace parts fixed in South Lake Conway Villa

The chimney is part of the fireplace's listing

A factory-built fireplace is tested with a specific chimney. Section R1005.4 says chimneys for use with factory-built fireplaces shall comply with UL 127, the same standard as the fireplace, and R1005.1 has factory-built chimneys listed and labeled, then installed and finished at the top as their maker directs.

That makes the metal chimney a matched part of the system. Repairs to pipe sections, supports or the top of the chimney use the components the fireplace's manual names.

Metal chimneys inside a framed chase

Many factory-built chimneys run up through a framed chase, a boxed enclosure that can look like a masonry chimney from outside. The chase has its own top cover, and in one maker's system its own chase-style termination.

The chase itself is house framing and siding, and the chase top cover is a separate job priced on its own line. The prefab repair covers the fireplace, the pipe and the parts of the listed system inside the chase.

Two chimneys in one chase

Some homes have two factory-built fireplaces venting through one chase. One maker suggests separating the terminations by at least 24 inches center to center and staggering their heights by 18 inches, to keep smoke from one drifting into the other.

When one fireplace smokes only while the other is burning, we look at the spacing at the top first. Changes there use the listed termination parts for each system.

• Center-to-center spacing
• Height difference between the tops
• Listed termination parts for each system

How to recognize a factory-built fireplace

A factory-built fireplace usually shows a metal frame around the opening, refractory panels inside, louvers or a metal top above the opening and a round metal chimney or a framed chase outside. A rating plate names the maker and model.

Decorative facing can hide most of those clues. We confirm the type at the free inspection, because the repair methods for a steel firebox and a masonry one have little in common.

• Metal frame around the opening
• Refractory panels inside
• Louvers or a metal top above the opening
• Round metal chimney or framed chase outside