Cracked panels and worn fireplace parts fixed in Oakshire

What refractory panels do inside the firebox

Many wood-burning factory-built fireplaces line their steel firebox with molded refractory panels on the sides, the back and the floor. One maker's parts list names separate left, right, rear, bottom rear and bottom front panels, held in place by retainers.

The panels take the direct heat of the fire and shield the metal behind them. When a panel breaks apart, the fire can reach steel that was never meant to face it, which is why panel condition is one of the first things we check.

• Left and right side panels
• Rear panel
• Bottom rear and bottom front floor panels
• Retainers that hold them in place

How high a factory-built chimney must reach

One maker's instructions follow a familiar rule for the top of the chimney. The top has to stand 3 feet or more above the highest point of its roof penetration, and 2 feet taller than any part of the roof that lies within 10 feet.

Additions and roof changes can put a higher roof section inside that 10-foot circle. If the chimney no longer meets the rule, we explain what the manual allows for extending it with listed sections.

• At least 3 feet above the roof penetration
• At least 2 feet above roof within 10 feet
• Extensions with listed sections only

Where the pipe passes through the roof

Where a metal chimney leaves the roof, a sloped metal cone is worked into the shingles and a storm collar wraps the pipe above it. One maker's manual calls for waterproof caulk around the collar's perimeter to seal it against the pipe.

The same manual warns against sealing the openings built into the rooftop cone. Split caulk, a collar that has slid down and a cone pulled loose by roof work are the leak points we find there, and each is repaired with listed parts.

The smoke shield and the top of the firebox

The top of a factory-built firebox includes parts such as a smoke shield and an inner dome that guide smoke toward the damper and the flue. In one maker's parts list, both are marked as not field replaceable.

Damage there changes the conversation. We tell you what we see, which parts can be serviced and when the finding means the fireplace should be replaced as a whole.

• Smoke shield
• Inner dome
• Damper area above them
• What the parts list allows in the field