The Official Publication
of the Mason Contractors
Association of America

February Issue

Current Issue:
February 2015


Codes and Standards

Masonry examines the importance of code compliance verification when using post-installed anchors in walls constructed of fully grouted concrete masonry units.

Grout-filled concrete masonry walls continue to be a common form of construction for many types of structures, from single-family homes and large retail stores/commercial buildings, to single-story structures and multiple-story hotels. In all of these structures, a need exists to attach various elements, structural and non-structural, to the load-bearing masonry walls. These attachments vary from roof structures to piping and equipment supports. It is important that the connection of these elements to the masonry walls be secure.

Connections between elements are important in applications like roof supports, ledgers, equipment attachments, racking stabilization and piping supports. These attachments can be accomplished by one or more of three main methods: embedment, cast-in-place anchorage, or post-installed anchorage.

In the embedment method, the element is placed within the masonry wall. This is the case in which a beam rests in the wall, and the wall is constructed around the beam. Another example is the placement of a channel or strut in the construction of the wall.

Cast-in-place anchorage is accomplished by placing a “headed bolt,” “j-bolt,” or other type of bolt in the masonry before the grouting process. This attachment method requires the contractor know the location of the anchor and is able to place it accurately in that location.

Post-installed anchors require the drilling of a hole in the masonry, but provide flexibility in location after the masonry structure is constructed. Currently, post-installed anchors can be categorized into three main groups: chemical or adhesive, expansion, or screw type.

  • Referenced standards (ASTM or UBC) for masonry components are the same.
  • Single-anchor tests are required at different embedments and for different diameters for both tension and shear.
  • Tests to determine the influence of geometrical conditions, such as spacing and edge distance are conducted. In some cases these tests are optional.
  • Suitability tests are required. For expansion anchors and screw anchors, these may include the effect of variations in drilled hole diameter or torque. For adhesive anchors, these will include effect of temperature, dampness and other environmental conditions.
  • Special loading tests include seismic tests and combined tension and shear loading tests. These tests may be optional.

Base material failure with close distance corner tension test
Base material failure with close distance corner tension test

Much information is available for post-installed anchorage to masonry. Manufacturers have tested some specific applications, such as attachment to the top of grout-filled CMU walls. It is nearly impossible for an Evaluation Report or manufacturers’ data to provide exact data for every application of anchorage to masonry. Some manufacturers may be able to provide additional guidance or data for applications not covered in their literature or in an ICC-ESR.

Designers and contractors can be confident that data published in Evaluation Service Reports has been verified by an independent testing agency and reviewed by personnel at ICC-ES. Users of Evaluation Service Reports should read the entire report, including findings, conditions of use and footnotes, and verify that the application being considering is covered properly by the Evaluation Service Report.

Post-installed anchorage is an effective method of attaching steel elements to grout-filled concrete masonry. Careful reading of manufacturers’ literature and independent assessments can help users achieve reliable connections.  

Pete Anderson is an approvals engineer with Hilti Inc. He has more than 25 years of experience dealing with codes and approvals issues related to post-installed anchoring into concrete and masonry.
Last Updated on Friday, 02 September 2011 15:12