Reinforcing an Industry

A look at anchors, fasteners and connectors

By Christopher Bupp

As masonry wall design continues to evolve into the 21st century, terms like “air and vapor barriers,” “steel stud assemblies,” “rigid insulation versus batt insulation,” “ventilation with weeps and vents,” “clear air space,” and “oversize masonry units” are all employed to describe today’s masonry wall. Each one of these items can have a direct impact on wall reinforcing and anchoring systems. Add to that list things like “green” and “sustainable,” and, well, you get the idea. Masonry has gone through quite a transformation over the last handful of years.

A look at anchors, fasteners and connectors for masonry

The newest buzz words of green and sustainable have been linked with masonry itself for a number of years because of masonry’s local manufacture, recyclability, thermal mass characteristics and obvious history of longevity.  Today, masonry units come in all different types, sizes and shapes. These newer products add even greater design flexibility with masonry, but also create the need for anchoring systems that have the adjustability to work with multiple type units in a single-wall design. While the masonry unit has always been considered green and sustainable, only recently have the wire reinforcing and anchoring systems followed suit to promote themselves as environmentally friendly with many products being made with as much as 99 percent post-industrial recycled material. This combination, along with the development of air/vapor barriers and flashings fabricated with a large percentage of recycled-content, have placed masonry wall construction at the top of the list for green and sustainable building envelope systems. Another choice design professionals have been increasingly selecting is the use of stainless steel for both wire reinforcement and anchoring systems to provide even more corrosion resistance and longevity. More government facilities, college and university projects, and even K-12 projects are designed with stainless steel to match the 100-year life cycle of masonry.

Anchored Masonry Veneers

By: Stephen Getz, BSCE

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 .

The two options for horizontal joint reinforcing of masonry walls are the truss and ladder types. Truss reinforcement is a stronger product, because of its greater effective steel area. However, the ladder type has become increasingly popular because of its ability to handle more movement and deflection in the wall. More important, as more masonry walls incorporate vertical reinforcement, the design of the ladder type allows for the cores of the block to remain open, so as not to interfere with the placement of the vertical rebar. Both truss and ladder type reinforcements are available in mill-galvanized (interior use only), hot-dipped galvanized (exterior use) and stainless steel finishes. Wire diameters of nine gauges and 3/16 inches are available.

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.

Product Watch

CoreLock Rebar Positioner

CoreLock by Wire-Bond to the Rescue

Wire-Bond, manufacturer of masonry wall reinforcing, anchors and accessories, recently introduced the CoreLock series of rebar positioners. The CoreLock Rebar Positioner fits inside the wall reinforcing and down into the CMU core. This recess of 1 1/4-inch into the core, as well as the diagonal design of the positioner, secures it down in the core. Once installed, it cannot be bumped or misaligned. Placement of the rebar in the middle of the core is assured, which results in labor savings.

Different styles are available to suit the needs of most wall sizes and applications. The figure-8 design is available for six– through 12-inch blocks. Double figure-8 designs are available for multiple bars. The Big O Positioner has a larger hole that can help simplify lapping, while keeping the rebar centered.

Positioners are packaged in a tangle-proof box for easy installation on the job. Available in mill galvanized, hot dipped and stainless steel. For more information, visit www.wirebond.com.

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 increases the need for these systems is today’s energy requirements, which in some parts of the country, may force the designer to use up to as much as four inches of rigid insulation in the cavity.

When running dew-point analysis in steel stud assemblies, it has become extremely popular to use rigid insulation in the cavity versus the old batt insulation in the studs to move that potential dew point out into the cavity area, thus minimizing condensation within the interior portion of the steel stud backup system. This concept has caused the need for increased thicknesses of insulation in the cavity, plus it has created the need for manufacturers to help the contractor in the field with attaching anchoring systems through the insulation and gypsum board.

Maybe the biggest change has taken place with regard to potential air and moisture infiltration in the wall assembly, and, more important, how we deal with keeping the building envelope as dry and energy efficient as possible. Anchoring systems certainly have become a major part of a successful building envelope, but not only from the anchoring standpoint. Today’s anchors must be compatible and function with all different types of both breathable and non-breathable air and vapor barriers. It is critical that the barrier’s integrity not be impaired, so as to maintain indoor air quality while also contributing to the structure’s energy compliance. In some cases, such as steel stud assemblies, the anchoring system will normally penetrate the air/vapor barrier and must provide an additional seal against air and moisture penetration at the outer-most point of the backup system. In CMU applications, the air/vapor barrier must be able to effectively seal around the previously installed anchors. In all cases the air/vapor barrier and the anchoring system need to be able to function properly together, thus requiring careful consideration during design and product selection.

A look at anchors, fasteners and connectors for masonry

Another veneer that has gained tremendous popularity during the last few years is the use of an almost unlimited number of real and imitation stone products. Developing anchoring systems for all the various types of stone materials (natural or synthetic) from different parts of the country has created a situation where most anchoring systems need to be “engineered” for each specific application. Once again, adjustability or flexibility of the placement of the anchor is paramount in these types of wall systems, keeping in mind the spacing requirements of a veneer system for the particular geographic region.

As things continue to change in the masonry industry and new wall systems are developed, the need for new and different types of anchoring products will continue to evolve. The high-performance wall concept will cause the masonry industry to look more closely at “systems” that incorporate, wire reinforcement, anchoring products, air/vapor barriers, flashings, control and expansion joints, weep and vents, mortar collection devices, drip plates, and termination bars into one functioning, fully tested system. The system concept needs to be embraced by our industry as we move forward.

– Originally published in Masonry magazine, Dec. 2007

Chrisopher Bupp, with Hohmann and Barnard Architectural Services, has been involved in the construction industry for more than 20 years. The building envelope has been his primary area of expertise. Contact Chris at chrisb@h-b.com.

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