Fireplace Brick Sizes

Basic Brick

• The first bricks were sized to the human hand and made twice as long as the width, because solid brick walls were laid with two sides of brick joined by other bricks across them. Technology and design styles have produced many new sizes and shapes. The original basic or common brick was nominally 2 by 4 by 8 inches, with actual dimensions slightly less to accommodate mortar joints of 3/8 to 1/2 inch.

ASTM Standard

• The American Society for Testing Materials has a size standard for bricks used to face walls, including fireplace surrounds. It defines a standard brick as 3 5/8 by 2 1/4 by 8 inches. Modular brick, made to conform to dimensions of other basic construction materials, is 3 5/8 by 2 1/4 by 7 5/8 inches.

Oversize

• There also are oversize bricks, larger than the standard or common brick. Roman, Norman and jumbo Norman bricks are all 11 5/8 inches long, 3 5/8 inches wide and 1 5/8, 2 1/4 or 2 3/4 inches thick, respectively. King and queen are 2 3/4 inches thick and 2 5/8 by 9 5/8 or 2 3/4 by 7 5/8, respectively.

Firebrick

• Firebrick is usually 9 inches long. Basic firebrick is 4 1/2 inches wide and 2 1/2 inches thick, but firebrick is available in other dimensions from 2 1/4 to 4 1/2 inches wide and from 1 1/4 to 2 1/2 inches thick. The size, shape and design of the interior firebox will determine the size of firebrick used to line it. Some fireboxes combine sizes to adapt to the shape of the firebox.

Actual Sizes

• Despite ASTM and brick industry standards, there really is no uniformity in brick sizes. Actual dimensions will vary among manufacturers, and installation will vary with the width of the mortar joints. Even bricks with the same general name, like standard or king, will vary slightly by manufacturer. Antique or salvaged bricks also are used to face fireplaces, and these dimensions may vary even more than new bricks.

Facing

• Fireplace facing or surround bricks are usually laid with the narrow face out, but can be installed with the wide face showing. Most modern brick fireplaces are actually facades, installed over wood sheathing. Older fireplaces may have solid brick walls. Metal fireboxes or inserts and flues also may replace firebrick inside the fireplace.