Installation Guide and Techniques
Over the years, White Cap has learned many helpful installation techniques from our manufacturers, code inspectors, and customers. We’d like to share these techniques plus some tips to help make sure that you’re up to code when installing.
There are a few things to remember when drilling holes for post-installed anchors. It’s a good idea to avoid a diamond core drill. While they are faster, they will leave a smooth-walled hole and adhesives will not perform as well. Most contractors use a hammer drill for a rougher hole. If you hit rebar you can switch to a core drill temporarily for speed, but once you’re past the rebar switch back to the hammer drill.
Note: It is not recommended to install mechanical anchors in oversized or core drilled holes.
For in-depth info on drilling into concrete, and tips for post-installed anchors, click here.
A properly drilled hole is a critical factor both for ease of installation and optimum anchor performance. The anchors selected and the drill bits to be used should be specified as part of the total anchoring system and should meet ANSI requirements. The following table lists the nominal drill bit diameter along with the tolerance range established by ANSI for the carbide tip.
For through-fixture installations (through-bolting), pre-drill or punch a minimum clearance hole large enough to allow the carbide-tipped bit and the anchor to pass through.
Mechanical wedge anchors require a pre-drilled hole large enough for the anchor to expand when driven through.
When adhesive anchors are installed in concrete in the freezing range, frost or ice can form on the walls of the anchor hole. If this happens, injection type adhesives may not properly bond. Spin-in type capsule systems, which scrape the walls of the anchor hole during installation, are less sensitive to this.
Do not use a torch; it carbonates the concrete on the walls of the anchor hole, creating a residual dust. Job site tests are recommended if a torch is used to dry the anchor hole.
A best practice is to specify an installation or maximum torque, especially for adhesive anchors. Refer to the installation guide for torque values of bolt-tightened anchors, adhesive anchors, and tested torque-controlled anchors.
The following factors may affect torque:
The industry standard for anchoring and fastening is to reduce the ultimate load (mean average) capacity by a minimum safety factor. This depends upon base material and governing construction code to calculate the allowable working load.
Allowable loads are only recommendations, and local construction codes should be consulted to determine the required safety factors and design methodology.
For adhesive anchors, both the strength of the adhesive at in-service temperature and the steel anchor element must be considered, and the lower of the strengths will govern. As in all applications, the contractor is responsible and should verify the actual safety factors, design load capacities and installation.
Seismic design is complex with many influencing factors: site geology, soil characteristics, building occupancy categories, building configuration, structural systems, lateral forces, and more.
Anchors to be used for seismic loads will not be fully loaded in place until an earthquake occurs. In shear, anchors are tested and subjected to alternating load applications. Anchors qualified for seismic applications must have evidence of performance in cracked concrete.
Testing and qualification of the structural injection adhesive is conducted and evaluated specifically for this application. Post-installed rebar must provide equivalent bond strength and basic tensile behavior to cast-in reinforcement for design and construction.
Although post-installed rebar behave like cast-in reinforcement, reinforced concrete design influences, such as fire safety, should be considered. Using proper design and installation practices, the post-installed rebar connections can be assumed to be monolithic or uniform.
Installation Guide and Techniques
As in all applications, the contractor responsible for the installation should determine the clearance hole, hole size, anchor selection, meeting code and code compliance.Note: It is not recommended to install mechanical anchors in oversized or core drilled holes.
Drilled Hole – Post-Installed Anchors
Follow manufacturer’s recommendations to thoroughly clean debris and dust from drilled holes. Contractors may be familiar with prior standards using compressed air, blow-bulbs, and tube brushes. The blow-brush-blow method is effective, but may cause additional complications. Many contractors are using special hollow-core carbide bits that attach to HEPA vacuums for faster hole-drilling and cleaning, and to be compliant with OSHA Silica Dust Containment regulations.For in-depth info on drilling into concrete, and tips for post-installed anchors, click here.
A properly drilled hole is a critical factor both for ease of installation and optimum anchor performance. The anchors selected and the drill bits to be used should be specified as part of the total anchoring system and should meet ANSI requirements. The following table lists the nominal drill bit diameter along with the tolerance range established by ANSI for the carbide tip.
Anchor Alignment
Install perpendicular to the base material surface. Be sure to calculate and verify that a bending load has not been created and to determine actual load capacity if your anchors are installed -/+ 6° perpendicular to base material surface.Clearance Holes
Post-installed fractional-sized anchors are designed to be installed in holes drilled in concrete and masonry base materials with carbide-tipped bits.For through-fixture installations (through-bolting), pre-drill or punch a minimum clearance hole large enough to allow the carbide-tipped bit and the anchor to pass through.
Mechanical wedge anchors require a pre-drilled hole large enough for the anchor to expand when driven through.
- For mechanical expansion anchor sizes up to 7/8”, the minimum clearance hole is the anchor diameter plus 1/16".
- For sizes 1" and larger, the minimum clearance hole is the anchor diameter plus 1/8". This may be adjusted to allow expansion for coatings applied to the fastener.
Temperature - Adhesive Anchors
Installation and base material temperatures can affect a product’s performance. Make sure the anchor and adhesive are suitable for the application and installation conditions. And, always follow manufacturer instructions for best results, especially in freeze/thaw conditions.When adhesive anchors are installed in concrete in the freezing range, frost or ice can form on the walls of the anchor hole. If this happens, injection type adhesives may not properly bond. Spin-in type capsule systems, which scrape the walls of the anchor hole during installation, are less sensitive to this.
Do not use a torch; it carbonates the concrete on the walls of the anchor hole, creating a residual dust. Job site tests are recommended if a torch is used to dry the anchor hole.
Installation Torque
Torque-controlled anchors are triggered by tightening a nut or bolt. For typical installations where it’s impractical to measure torque, it’s common practice to apply 3-5 turns to the bolt or nut head from the hand-tightened position, or tighten to within the maximum torque range.A best practice is to specify an installation or maximum torque, especially for adhesive anchors. Refer to the installation guide for torque values of bolt-tightened anchors, adhesive anchors, and tested torque-controlled anchors.
The following factors may affect torque:
- Anchor type
- Anchor material
- Base surface materials
- Coating or platings
- Lubricating anchor components due to drying sealant use
Design Criteria
ALLOWABLE STRESS DESIGN (ASD)The industry standard for anchoring and fastening is to reduce the ultimate load (mean average) capacity by a minimum safety factor. This depends upon base material and governing construction code to calculate the allowable working load.
Allowable loads are only recommendations, and local construction codes should be consulted to determine the required safety factors and design methodology.
For adhesive anchors, both the strength of the adhesive at in-service temperature and the steel anchor element must be considered, and the lower of the strengths will govern. As in all applications, the contractor is responsible and should verify the actual safety factors, design load capacities and installation.
Anchors for Use in Seismic Design
Based on building codes, seismic design requires building structures resist the ground-shaking and lateral side-to-side movement effects from earthquakes. Each structure is assigned to a seismic design category/zone based on the building location.Seismic design is complex with many influencing factors: site geology, soil characteristics, building occupancy categories, building configuration, structural systems, lateral forces, and more.
Anchors to be used for seismic loads will not be fully loaded in place until an earthquake occurs. In shear, anchors are tested and subjected to alternating load applications. Anchors qualified for seismic applications must have evidence of performance in cracked concrete.
Post-Installed Rebar Connectors
Post-installed rebar connections are also designed to provide non-contact bar splices. The connection rebar is installed and bonded in drilled holes in hardened concrete with a tested and qualified structural injection adhesive.Testing and qualification of the structural injection adhesive is conducted and evaluated specifically for this application. Post-installed rebar must provide equivalent bond strength and basic tensile behavior to cast-in reinforcement for design and construction.
Although post-installed rebar behave like cast-in reinforcement, reinforced concrete design influences, such as fire safety, should be considered. Using proper design and installation practices, the post-installed rebar connections can be assumed to be monolithic or uniform.