What is the difference between Structural Glazed Tile (SGT) and Glazed Brick?

This is a question I am asked quite often during sales seminars given at distributors offices and at architectural and engineering firms. The units may look the same once installed in the wall, however, it is what’s behind that pretty face that determines the difference. I would like to briefly go into some of the similarities and differences between the two products.

Both glazed brick and SGFT have a ceramic glazed face and a clay, fire clay or mixtures thereof, body which must meet the high quality standards as outlined in ASTM C-126 or ASTM C-1405.

Traditionally SGFT has been considered an interior unit. In the larger “tile” units, the cells or core holes run horizontally through the units and can be used in loadbearing and non-loadbearing applications. There is also a wide variety of shapes in the standard offering with SGFT.

Glazed brick, on the other hand, has traditionally been considered an exterior veneer unit that comes in the smaller “brick” sizes. The core holes typically run vertically through these units. Brick also has a durability standard, which must be met with exterior use. In order to do this, we must specify for durability of the intended application of the glazed brick. In 1998, a new standard was developed to incorporate more stringent standards for ceramic glazed brick as compared to standard face brick use. The standard use for specifications should be used as follows: Ceramic Glazed Brick Units shall be Quality Ceramic Glazed Fire Clay Units as manufactured by the Elgin Butler Company or approved equal and conforming to the specifications of with ASTM C-1405, Grade S, Type I & II, Class Exterior (or Interior), Division as either: Solid (void area less than or equal to 25%), or H40V (void area greater than 25% but less than or equal to 40%), or H60V (void area greater than 40% but less than or equal to 60%). Sized for 3/8″ mortar joints. (Contact manufacturer for availability of Division specification available in each size.) The class in this standard considers the severe weather exposure in regard to water penetration of the finished assembly and also the freeze/thaw cycles, which are not considerations under the SGFT standard of ASTM C-126.

In today’s marketplace these traditional lines have been blurred. Glazed brick is now being used in interior walls and Elgin-Butler’s Structural Glazed Facing Tile can be used as exterior walls. In any exterior glazed application, the design and installation is extremely important. Cavity wall construction and expansion joints are recommended, just as with facing brick, along with the installation of flashing, weep holes, and/or vents. The coring or cells must be laid vertically to allow for proper drainage. The properties of glazed brick allow it to be brought into the interior with little or no adjustments necessary for the installation.

Note: This article has been revised (10/03)from its original copy to incorporate the new then revised ASTM C-1405.