Masonry Magazine August 1980 Page. 20
Steel Angles
When a continuous steel angle is used to support the new brick veneer at the foundation wall, it should be of steel conforming to ASTM A 36, and should be treated or coated to resist corrosion. Bolts or other fasteners should also be corrosion-resistant.
The sizing of the angle, and the sizing and spacing of the bolts should be determined by structural analysis.
Steel angles for lintels should be a minimum 1/4 in. (6.2 mm) thick with at least 3-in. (75 mm) legs and the steel should conform to ASTM A 36. For information on steel lintels for brick masonry, see Technical Notes 31B.
Flashing
Flashing materials for use with brick veneer may be bituminous membranes, plastics, sheet metals, or combinations of these. It is best to select only superior materials because replacement in the event of failure will be costly, if not impossible. Asphalt impregnated felt paper should not be used as a flashing material. For a more complete discussion on the various types of flashing, see Technical Notes 7A.
Weepholes
Weepholes are formed by inserting a material into the mortar joint, or by omitting all or part of the head joint. Forming materials, such as well-oiled rods, are removed to leave an unobstructed opening. Other forming materials, such as plastic tubes or rope wicks, may be left in place. Sometimes metal screening, fibrous glass, or other materials, are placed in open weepholes, but this should not be done indiscriminately. Materials such as metal screening can corrode and cause staining of the masonry.
CONSTRUCTION
Supports
Foundations. Supporting brick veneer on new or existing foundations requires excavating down to the existing foundation. The excavation must be sufficiently wide for the brickmason to work. Prior to placing the masonry on an existing foundation, the foundation should be brushed clean of loose soil and debris.
Angles. When constructing brick veneer on continuous corrosion-resistant steel angles, the first course of brick should be laid in a mortar setting bed. This provides a means to compensate for any variations and misalignment of the steel angles.
Installing Additional Insulation
Applying brick veneer over existing construction offers an opportunity to better insulate the existing exterior walls. The insulation materials used should comply to the criteria discussed in Technical Notes 21A.
Rigid insulation may be installed directly over the existing finish prior to erecting the new brick veneer. A 1-in. (25 mm) air space should be maintained between the brick veneer and the rigid insulation. If the existing wood frame or metal stud walls contain little or no insulation, the existing siding of the wall may be removed so that insulation can be installed within the wall. The materials removed from the existing wall may be reapplied.
Workmanship
Good workmanship is necessary to achieve satisfactory performance of brick veneer. The veneer must be properly constructed if the expected performance of the masonry is to be obtained.
Mortar Joints. There is no substitute for the complete filling of all mortar joints that are intended to receive mortar. Partially filled mortar joints result in leaky walls, reduced strength of the masonry, and may contribute to cracking and spalling due to freezing and thawing in the presence of moisture. All joints intended to receive mortar should be completely filled as the brick are laid.
Keeping the Air Space Clean. It is essential to maintain a 1-in. (25 mm) air space between the brick veneer and the existing wall, and to keep it clean of mortar protrusions, droppings, and other foreign materials. If mortar falls into the air space, it may form "bridges" for moisture and thermal transfer, or it may fall onto the flashing and block the weepholes.
Tooling of Joints. Weather tightness and textural effect are the basic considerations of mortar joint finish selection and execution. Tooling the joint properly helps the mortar adhere to the edges of the brick units and seal the wall against moisture penetration. The use of concave, V, or grapevine joints is recommended. The joints should be tooled when the mortar is "thumb-print" hard. Additional information on joints may be found in Technical Notes 21C.
Flashing and Weepholes. Flashing materials must be carefully installed to prevent punctures or tears. The flashing must be securely attached to the existing wall and should extend through the face of the brick veneer. Weepholes should be installed in the head joints immediately above all flashing.
Tie Placement. Secure attachment of the ties to the existing wall is a necessity. The ties must be of sufficient length to provide a minimum 2-in. (50 mm) embedment into the bed joints. Ties should be placed in the bed joints and should be completely surrounded by mortar.
Caulking or Sealants. Caulking joints at the perimeter of exterior door and window frames should not be less than 1/4 in. (6 mm) nor more than 3/8 in. (10 mm) wide. They should be cleaned for a depth of 1/4 in. (20 mm). The joints should be properly primed before placing caulking compound or sealant. The caulking or sealant should be placed with a pressure gun.