1.1 This specification covers brick intended for use as the lining in the fireboxes of residential fireplaces.

1.2 Firebox brick are manufactured from clay, fire clay, shale, or similar naturally occurring earthy substances and subjected to a heat treatment at elevated temperatures (firing). The heat treatment must develop a fired bond between the particulate constituents to provide the strength and durability requirements of this specification.

Note 1 - Firebox brick are typically installed using ground fire clay mortar or refractory mortar. Mortar joints are typically 1/ 8 in. (3.2 mm) thick, just thick enough to accommodate dimensional variations in the firebox brick.

1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.

1.4 The text of this specification references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this specification.