Masonry Magazine December 2007 Page. 36
CONNECTORS, ANCHORS AND FASTENERS
With the increasing availability of non-standard sizes of masonry units and veneer products, innovative and creative wall designs are now more common. This demands that the anchoring systems have the requisite adjustability to function correctly within these masonry walls. Building codes dictate a maximum of 1 1/4 inches of vertical adjustability for typical hook-and-eye anchoring systems, but with these modern wall designs, even more adjustability may be required. Products are now on the market that allow over three inches of vertical adjustability and maintain required load values.
Another hot topic is the development of new anchoring systems that eliminate the "disengagement" possibility of the anchor from the backup system. Most of these newer systems incorporate a "closed-loop" section for attachment of the anchor, thus eliminating the possibility of the anchor separating from the back-up resulting from differential movements. Additionally, some of the "closed-loop" systems allow the anchor to handle wall movement in both the vertical and horizontal directions.
Awareness of seismic activity
requires the use of high-strength
products
that can meet the
demanding needs of
the earth's natural
disasters.
High-strength anchoring systems have become necessary to meet design criteria in areas with high-wind loads, especially in multi-story structures. The ever-increasing awareness of seismic activity and its affect on masonry walls also requires the use of high-strength products that can meet the demanding needs of the earth's natural disasters. In many cases, these systems include heavier gauge wire and metal components that require special manufacturing to meet today's stricter codes. Processes like totally flat weld connection points and flattening of the pintle section in the veneer joint are absolutely necessary in these high-strength systems when the wire diameter may be as much as 1/4 inch to meet engineering requirements. Another factor that
BY: STEPHEN GETZ, BSCE
Anchored
Masonry
Veneers
A brick veneer cavity wall will provide a durable, long-lasting, aesthetically appealing finish to all commercial buildings.
Construction of the veneer on a brick veneer cavity wall relies on quality products and tradesmen to fulfill the design life and functional expectations of the owner and its occupants.
As part of the building's veneer design criteria, the brick tie anchoring system should be carefully evaluated and reviewed with consideration to the following:
• Tie stiffness
• Tie strength
• Tie spacing
• Fastener requirements
• Air barrier interface
• Material type and finish
• Tie versatility.
Construction of brick cavity walls tied to back-up materials other then masonry relies on a relatively stiff brick tie anchoring system for an optimum performing façade. The result minimizes excessive veneer deflection under wind load, which creates less potential for cracking of the veneer. Less cracking means less water migration into the cavity.
A tie illustrating good strength performance characteristics accommodates placement spacing greater than a typical 16-X 16-inch pattern as used with conventional plate and pintle ties, and increases the spacing area to 16 X 24 inches. This generous spacing would remain compliant with standard veneer wall construction requirements of the ACI 530/ASCE 5/TMS 402 criteria. It's important to note that when applying the greater spacing, the quantity of ties required is reduced by almost one-third, which generates a significant cost savings to the owner without compromise to the veneer's performance.
One must also consider a compatible fastener for the connection of the tie assembly to the stud-framing backup. A suitably designed brick anchoring system that utilizes a single fastener for its backup connection will provide a cost-effective installation and lessen the quantity of breaches in the air barrier by 50 percent over conventional ties. A quality Tek screw for steel stud or lag screw for timber connections is efficiently installed and available in material compatible to the anchor plate material.
Finally, the use of insulation in brick veneer cavity wall construction is a popular means to conserve building energy. A tie system must be adaptable for various wall configurations and accommodate insulation of varying thicknesses.
CTP Inc., for example, provides wall ties and anchors that illustrate tie stiffness three times that of conventional ties in the marketplace. The base plate can utilize a single screw fastener for 16-gauge metal stud and timber connections and is manufactured in sizes to bridge various insulation thicknesses. Spacing of the ties is recognized at the maximum permissible by code. The complete assembly is available in hot-dip galvanized or stainless steel finishes. The tie system also utilizes a proprietary multi-functional V-shaped tie that can be used for standard brick veneer construction, or be utilized with reinforcement for seismic applications. The installation is efficient and notably strong.
Stephen Getz, BSCE, is president of Construction Tie Products Inc. For more Information, visit www.ctpanchors.com.