Brick selection is usually based on aesthetic factors, first, such as size, color, and texture. These aesthetic factors can dramatically affect the perception of a completed building. For designers making the aesthetic selections, there is usually little concern for the brick construction.
Brick used for building veneers is available in two primary types: solid brick (facing brick) and hollow brick. Different standards govern the manufacturing of these two brick types. Facing brick is manufactured to ASTM C216. Hollow brick is manufactured to ASTM C652.
The principal difference between the two brick types is the voids permitted. Facing brick must be a minimum 75% solid. Hollow brick is available in two Classes defined by ASTM C652 as H40V and H60V that are distinguished by the required voids.
- H40V - 25% minimum and 40% maximum voids
- H60V - 40% minimum and 60% maximum voids
Facing brick voids are created by cores or frogs. Hollow brick voids are cores, frogs, or cells. Cells are, in effect, large cores required to accomplish the larger voids. Cores and cells can be combined in the same brick for hollow brick to create double face shell or cored face shell bricks.
ASTM standards require identical physical properties for facing brick and hollow brick. The standards regulate compressive strength, water absorption, and saturation coefficient properties that help predict the brick durability and performance. Since the minimum properties are the same for facing brick and hollow brick, similar performance can be expected.
So Why Choose?
Remember, aesthetics, first! The designers must be happy with the size, color, and texture of the selected brick. The aesthetics of a facing brick and hollow brick may not match well enough to permit an option.
Environmental stewardship. Hollow bricks use less natural resources to manufacture: less clay and water to form, less energy to fire, less fuel to transport - all these benefits simply by increasing voids and reducing mass, without sacrificing performance.
Structural performance. The H60V hollow brick with large cell voids will permit vertical reinforcing and grouting for structural applications, an application not possible with facing brick.