A Practical Guide for Anchor Testing on Construction Sites
Anchor testing is a critical verification process for safety-critical fixings in structural and non-structural applications. However, there is still widespread confusion across projects about the role of ETAs, the meaning of cracked and non-cracked concrete and who is permitted to carry out different forms of anchor testing.
This article clarifies these points in practical, site-ready terms.
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Do You Need an ETA to Carry Out a Proof Test?
No — an ETA is not required to carry out a Proof Test.
An ETA (European Technical Assessment) is a formal performance assessment carried out by an independent test house at the request of a manufacturer. It provides verified performance data for an anchor system in specific base materials and loading conditions.
However:
- Not all products carry an ETA
- In the absence of an ETA, the manufacturer must provide technical performance data
- Designers may still specify anchors without an ETA provided adequate design data exists
A proof test is a site verification test, not a product approval test.
What is required for a proof test is:
- The applied design load from the structural designer
- The corresponding proof test load, calculated from that applied load
- A competent tester to carry out the procedure
The proof test simply verifies that the installed fixing can safely resist the design load in the actual substrate on site.
It does not certify the anchor system.
What Is Cracked and Non-Cracked Concrete? (In Simple Terms)
This is one of the most misunderstood concepts in anchor design. Whether concrete is classified as cracked or non-cracked is not a visual inspection. It is a structural design decision and it is defined in Eurocode EN 1992-4, Clause 4.7 — Determination of Concrete Condition.
In simple terms:
Non-cracked concrete
- Concrete that is not subject to tensile stresses
- Typically compression-only zones
- Example: mass foundations, heavily compressed walls
Cracked concrete
- Concrete that is subject to tensile or bending stresses
- Micro-cracking is assumed under service loading
- Example: suspended slabs, beams, cantilevers, transfer structures
The easiest way to think about it:
If the concrete element is bending or carrying tension, it must be assumed to be cracked. A typical example is the underside of a suspended slab, which is in tension under bending and therefore must be classified as cracked concrete for anchor design. The classification is the responsibility of the structural designer, not the tester or installer.
Can a Proof Tester Carry Out Allowable Load Testing?
Not automatically.
There is an important distinction between:
- Proof Testing
- Allowable Load Testing
Proof Testing
- Verifies an anchor installation against a known design load
- Confirms workmanship and substrate quality
- Uses a predefined proof load
- Does not generate design data
This is typically carried out by testers who have completed the CFA Basic Anchor Testing Course.
Allowable Load Testing
Allowable load testing is a higher-level engineering test used to:
- Establish anchor capacity in an unknown substrate
- Derive site-specific allowable working loads
- Support retrospective design verification
- Validate non-standard fixings or substrates
It involves:
- Incremental loading to failure or defined criteria
- Statistical assessment of multiple tests
- Interpretation against safety factors
- Engineering judgement
Because of the complexity and liability, allowable load testing should only be carried out by testers who have completed the CFA Advanced Anchor Testing Course and are deemed competent. Both the CFA and British Standards state that on-site anchor testing should only be undertaken by a competent tester.
Do You Need an ETA for Allowable Load Testing?
No.
Allowable load testing is a site-specific performance test, not a product approval.
It is used precisely because:
- The product may not have an ETA
- The substrate may be unknown
- The installation conditions are non-standard
- The test itself generates the performance data.
However, the results must be interpreted by a competent engineer and applied with appropriate safety factors.
Final Note
Anchor testing is a safety-critical verification process. Whether you are proof testing installed fixings or establishing allowable loads in unknown substrates, competence, correct methodology and clear design responsibility are essential.
Where information from the client is limited, testers should only test fixings they are satisfied are suitable for the substrate and only against clearly defined applied loads provided by the designer.
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Expert Verification & Authorship: Mihai Chelmus
Founder, London Construction Magazine | Construction Testing & Investigation Specialist |
