The New York Times

“You can also build a custom mantel, like Vincent DiSalvo, a principal of DiSalvo Contracting in New York, frequently does for his clients.

Installing a new mantel is fairly straightforward, Mr. DiSalvo said, “as long as you work within the parameters of code requirements,” and size it properly to fit the existing opening. Combustible materials — like a wood mantel — must be at least six inches back from the sides of a wood-burning firebox, he said, and “the horizontal piece that runs across the top of the firebox should be around 12 inches” above the opening, depending on how far the mantel projects off the wall.

The resulting gap between the firebox and mantel creates another design opportunity, he noted, and can be finished with distinctive ceramic tile or stone.”

“For a more monolithic appearance, a fireplace can be resurfaced in concrete or natural stone in the same way. If you use natural stone, though, choose a dark one, like slate, rather than a light one, like white marble, Mr. DiSalvo advised: “You want to select a stone that isn’t easily stained by soot. A darker-colored stone holds up better over time.”