Anchor Installation – Mounting Methods and Best Practice

Correct anchor installation is essential to achieving the performance intended by the anchoring system. Even a correctly selected anchor may not provide the required resistance if the drill hole, installation depth, tightening or curing procedure does not meet the specified requirements.

The appropriate installation method depends on the anchor type, base material, fixture geometry and application. Product-specific installation instructions and the relevant European Technical Assessment (ETA) should always be followed where applicable.

Why correct anchor installation matters

Anchor performance depends on the interaction between the fixing and the surrounding base material. Installation therefore forms an important part of the complete anchoring system.

Factors that can influence the quality of an installation include:

• Correct identification of the base material
• Drill-hole diameter and depth
• Drilling method
• Drill-hole cleaning
• Anchor embedment depth
• Fixture thickness
• Installation torque where specified
• Curing time for bonded anchors
• Edge distance and anchor spacing
• Installation temperature and environmental conditions

The installation requirements for the specific anchoring system should be checked before work begins.

Before installing an anchor

Before drilling, confirm that the selected anchor is suitable for the application and base material.

Important checks can include:

• The type and strength of the base material
• Whether concrete is cracked or non-cracked
• The applied tension and shear loads
• Required edge distances and anchor spacing
• Concrete-member thickness
• Fixture or clamping thickness
• Required embedment depth
• Environmental exposure
• Fire or seismic requirements where applicable

Explore anchoring base materials >

Drilling the correct anchor hole

The diameter, depth and quality of the drill hole can directly influence anchor installation and performance.

Use the drill diameter and drilling method specified for the particular anchoring system. The required hole depth may be greater than the effective embedment depth and should not be estimated from the overall anchor length alone.

The drill should also be suitable for the base material. Worn or inappropriate drill bits can create holes outside the intended dimensions.

Where reinforcement, prestressing tendons or other embedded services may be present, the drilling location should be assessed before installation.

Cleaning the drill hole

Drilling creates dust and debris that can interfere with anchor installation. Correct hole preparation is particularly important for bonded and chemical anchoring systems because the bonding material needs effective contact with the wall of the drilled hole.

Depending on the anchoring system, the required procedure may involve brushing, blowing, vacuum cleaning or another specified method.

The exact cleaning procedure should always follow the product installation instructions rather than applying one generic sequence to every anchor.

Learn more about drill-hole and installation conditions >

Common anchor mounting methods

Anchors can be installed using different mounting arrangements depending on the fixture and application. Three common methods are pre-positioned fixing, through fixing and stand-off fixing.

Pre-positioned fixing

With pre-positioned fixing, traditionally referred to as attachment mounting, the anchor is installed in the base material before the fixture is positioned.

The fixture is then placed over the installed anchor and secured using the appropriate nut, washer, screw or other fastening component.

This method can be useful where the anchor itself does not need to pass through the component being fixed.

Through fixing

With through fixing, traditionally referred to as push-through mounting, the fixture is positioned first and the anchor is installed through the fixture into the base material.

This can simplify alignment because the fixture itself can be used to position the drill holes, particularly where several fixing points are required.

The selected anchor must be suitable for through installation and long enough to accommodate the fixture thickness while still achieving the required embedment depth.

Stand-off fixing

Stand-off fixing, traditionally referred to as spaced mounting, is used where the fixture must be positioned at a defined distance from the surface of the base material.

This type of connection may introduce additional bending or eccentric loading into the anchorage because the applied force acts away from the surface of the base material.

The resulting load conditions should therefore be considered during anchor selection and structural design.

Learn more about anchor loading >

Mounting methods at a glance

Installing mechanical anchors

Mechanical anchors transfer load into the base material using mechanisms such as expansion, undercutting or mechanical interlock.

The installation method depends on the specific product. Important requirements can include:

• Specified drill-hole diameter and depth
• Required embedment depth
• Correct anchor position
• Specified tightening torque
• Minimum edge distances and spacing
• Correct setting procedure

Expansion anchors that rely on controlled tightening should be installed using the torque stated in the relevant product documentation.

Over-tightening or under-tightening can affect how the anchor develops its intended expansion forces and should therefore be avoided.

Installing chemical anchors

Chemical or bonded anchors use a resin or bonding material to transfer loads between the anchor element and the surrounding base material.

Installation typically requires careful control of:

• Drill-hole diameter and depth
• Hole-cleaning procedure
• Resin preparation and dispensing
• Anchor insertion
• Installation temperature
• Curing time
• Anchor loading after curing

The exact installation procedure varies between systems and should always follow the instructions supplied for the selected product.

Compare mechanical and chemical anchors >

Correct installation torque

Some mechanical anchoring systems require a specified tightening torque to achieve the intended installation condition.

Where a torque value is specified, suitable torque-controlled equipment should be used and the product-specific requirement should be followed.

There is no universal installation torque for concrete anchors. The correct value depends on the anchor type, diameter, material and design of the fixing system.

Curing time for chemical anchors

Bonded anchors must be allowed to cure sufficiently before the anchorage is loaded.

Curing time can depend strongly on the temperature of the base material and the chemistry of the anchoring system. Lower temperatures may require significantly longer curing periods.

The curing time stated in the relevant installation instructions should therefore be observed before applying the design load.

Fixture thickness and anchor length

The thickness of the component being fixed forms part of anchor selection, particularly for through fixings.

The selected anchor needs to accommodate the complete fixture arrangement while still achieving the required embedment within the base material.

The installation may need to account for:

• Fixture thickness
• Washers
• Levelling components
• Insulation or intermediate layers
• Required embedment depth
• Thread engagement

Using an anchor that is too short may prevent the required embedment depth from being achieved.

Common anchor installation mistakes

Installation errors can reduce the reliability of an anchoring system even when the correct product has been selected.

Common issues include:

• Using the wrong drill diameter
• Drilling to an incorrect depth
• Insufficient drill-hole cleaning
• Installing an anchor in an unsuitable base material
• Using insufficient embedment depth
• Ignoring minimum edge distances or anchor spacing
• Incorrect tightening torque
• Loading a bonded anchor before it has cured
• Using an anchor outside the conditions of its approval

Following the product-specific installation instructions is one of the most important steps in achieving the intended anchor performance.

Installing anchors in cracked concrete

Where anchors are installed in areas of concrete that may crack, the selected fixing must be suitable for cracked concrete where required.

Correct installation remains essential because the anchor must be capable of developing its assessed performance under the conditions for which it has been approved.

Cracked-concrete suitability should not be confused with seismic approval. Where seismic performance is required, the anchor must have the relevant assessment for that application.

Learn more about cracked and non-cracked concrete >

How installation affects anchor load capacity

Anchor resistance is based on defined installation and application conditions. Changes to embedment depth, spacing, edge distance or installation quality can therefore affect the available resistance.

For structural applications, installation geometry should be considered together with:

• Tension and shear loads
• Combined loading
• Concrete strength
• Cracked or non-cracked concrete
• Anchor spacing
• Edge distances
• Member thickness

Explore tension, shear and combined anchor loads >

Design the anchorage before installation

For structural applications, the anchoring arrangement should be assessed before installation begins. This is particularly important for multiple-anchor connections, high loads, restricted edge distances or applications involving cracked concrete.

The Fabory Anchor Calculator helps you design post-installed anchors for structural use in concrete in accordance with EN 1992-4.

Use the calculator to:

• Assess tension and shear loading
• Calculate combined loading conditions
• Account for cracked and non-cracked concrete
• Evaluate anchor spacing and edge distances
• Consider anchor position and configuration
• Assess fire and seismic conditions where applicable
• Generate calculation reports for project documentation

Use the Fabory Anchor Calculator >

EN 1992-4, ETA and installation requirements

For post-installed structural fastenings in concrete in Europe, EN 1992-4 provides the design framework used together with the performance data for the selected anchoring system.

The relevant European Technical Assessment (ETA) can define conditions including:

• Suitable base materials
• Concrete strength classes
• Cracked or non-cracked concrete
• Anchor dimensions
• Embedment depths
• Minimum edge distances and spacing
• Member thickness
• Installation procedures
• Permitted loading conditions

The installation instructions provided for the individual product form part of achieving the assessed performance and should therefore be followed throughout installation.

Explore more anchoring guidance

Continue exploring Fabory's technical anchoring guidance:

• Types of anchors >
• Understanding anchor loads >
• Anchoring base materials >
• Cracked and non-cracked concrete >
• Anchoring conditions >
• Practical anchor design >
• Explore all anchoring technical guidance >

Need help with an anchoring application?

Anchor installation can become more complex where structural loads, multiple anchors, restricted edge distances, bonded anchors or additional fire or seismic requirements are involved.

Fabory's technical specialists can help you assess the application requirements and identify a suitable anchoring solution.

Contact our technical specialists >

Frequently asked questions about anchor installation

Find answers to common questions about anchor mounting methods, drilling, installation torque and chemical anchor curing.