August 11, 2010

Glazed brick has been a mainstay in building construction for more than 4,000 years, cladding some of the world's oldest pyramids, the ruins of Babylon, and ancient ruins of Greek cities.

While construction techniques are much more refined today, modern day builders are still challenged with designing durable glazed-brick walls.

The main challenge, according to the Brick Industry Association, is ensuring proper drainage of water and moisture out of the wall system. This can be especially difficult for glazed-brick construction because of the impervious nature of the ceramic glazed surface. The smooth, glass-like surface is extremely durable and resistant to staining, scratching, abrasion, and even fire, but unlike traditional brick, it will not allow moisture from wind-driven rain or condensation to evaporate from behind the brickwork.

To ensure proper drainage, the BIA recommends a vented drainage wall system with two inches of air cavity space between the brick veneer and the interior wall. Water and moisture that enters the wall system will drain down the back of the brick and out of the wall through a series of flashing and weeps installed at all horizontal interruptions—including above lintels and shelf angles, beneath sills, under copings and masonry/stone caps, and at the wall base.

Open head joint weeps are recommended with a spacing of no more than 24 inches on center. Weeps should have a minimum diameter of 3/16 inch and be spaced no more than 33 inches on center.

Since mortar joints can account for up to 20% of the brickwork surface, it's crucial to specify a mortar joint profile that is most resistant to water penetration. BIA recommends the use of either concave “V” joints or grapevine-tooled joints for glazed-brick construction.

Other important design tips:

Extend flashing to the face of the brickwork or beyond, and turn the flashing ends into the head joint a minimum of one inch to form an end damPlace vents at the top of walls and below horizontal interruptions, such as shelf angles and flashing locationsUse open head joint weeps as vents. If open head joints cannot be used, then make sure to install the vents one or two courses above the weeps.Space vents 24 to 48 inches on center, and stagger the vents in relation to the overlying weeps.

For more, see BIA Technical Note 13, “Ceramic Glazed Brick Exterior Walls,” www.bia.org.