Masonry Magazine August 1980 Page. 19
Lintels may be of reinforced brick masonry, steel angles, or precast concrete. Reinforced brick masonry and steel angle lintels are the most commonly used in brick veneer construction. The minimum required bearing length for steel angle lintels is 4 in. (600 mm). The spans and sizes of steel angle lintels may be modified by fireproofing requirements in local building codes. Further information on the design, detailing and material selection of lintels may be found in Technical Notes 17H and Technical Notes 31B.
Top of the Veneer
A typical detail for the top of the brick veneer at an existing eave is shown in Fig. 4. There should be at least a -in (3.2 mm) clear space between the top of the last course of brick and the bottom of the soffit. This space should be covered with a new moulding strip and sealant or caulking. If there is insufficient eave to properly cover the top of the veneer, provisions must be made to extend the eave.
Selection of Materials
The proper selection of quality materials is essential to the satisfactory performance of a brick veneer wall assembly. No amount of design, detailing or construction can compensate for the improper selection of materials.
Brick
Nominal 3-in. (75 mm) or 4-in. (100 mm) thick brick, conforming to ASTM C 62 or ASTM C 216, should be used for brick veneer. Grade SW brick is recommended because the brick wythe is isolated from the remainder of the wall by the air space, thus exposing it to the maximum temperature extremes. Salvaged brick should not be used because they may not provide the strength and durability necessary for satisfactory performance. The use of salvaged brick is discussed in Technical Notes 15.
Mortar
The use of the correct mortar is very important to the successful performance of brick veneer. Portland cement-lime mortars are recommended because they have a long history of proven performance. Portland cement-lime mortars for brick masonry are discussed in Technical Notes 8 Series. Type N portland cement-lime mortar is recommended for brick veneer, except that Type M portland cement-lime mortar should be used for brick veneer below grade, where the brickwork is in contact with earth.
Ties
The type of tie system which should be used with brick veneer will depend on the construction of the existing wall. Corrugated metal ties may be used with EXISTING ROOFING NEW MOULDING CAULKING OR SEALANT BUILDING PAPER- 1(25 mm) AIR SPACE NEW BRICK VENEER 16(3.2 mm) SPACE MIN. Bd NAIL CORRUGATED METAL TIE EXISTING WOOD FRAMING Typical Eave Detail FIG. 4 wood frame backup. Metal wire ties should be used elsewhere. Several types of ties which may be used in brick veneer applied to existing construction are shown in Figs. 2a through 2d in Technical Notes 28 Revised.
Corrugated Metal Ties. Corrugated metal ties should be corrosion-resistant. They should be at least 22 gage, 76 in. (22 mm) wide and 6 in. (150 mm) long.
Metal Wire Ties. Metal wire ties should be at least 9 gage and corrosion-resistant. It is recommended that 3/16-in. (4.7 mm) diameter metal wire ties be used to fasten the brick veneer to a structural frame. Metal wire ties should comply with ASTM A 82 or A 185.
Corrosion Resistance. Corrosion resistance is usually provided by copper or zinc coating, or by using stainless steel. To ensure adequate resistance to corrosion, coatings or materials should conform to: Zinc-Coating of Flat Metal-ASTM A 153, Class B- 1, B-2, or B-3; Zinc-Coating of Wire-ASTM A 116, Class 3; Cop- per Coated Wire-ASTM B 227, Grade 30 HS: Stain- less Steel-ASTM A 167, Type 304.
Tie Fasteners
The type of fastener used to attach the ties to the existing wall will also depend on the construction of the existing wall.
Wood Frame. Corrosion-resistant nails should be used to attach the corrugated metal ties to wood frame construction. The nails should penetrate at least 114 in. (40 mm) into the wood studs.
Metal. Corrosion-resistant, self-tapping metal screws should be used to attach metal wire ties to metal con- struction. The screws should penetrate at least 1/2 in. (13 mm) into the metal.
Concrete or Masonry. There are several methods of attaching the metal wire ties to existing concrete or masonry walls. The ties may be attached with lag bolts and expansion shields or masonry nails. The fasteners and anchors should be corrosion-resistant.