An anchor pull test confirms that a fixing installed into concrete or masonry will carry the load the design relies on. A calibrated hydraulic tester applies a controlled tension load to the anchor, and the surveyor records how it performs, giving documented evidence that the installation is sound before it goes into service. The test follows BS 8539, the British Standard code of practice for the selection and installation of post-installed anchors in concrete and masonry.
Testing matters because a fixing is only as reliable as the base material it is set into and the quality of the installation, and neither can be safely assumed. An anchor pull test removes the guesswork and turns a fixing into something you can sign off with confidence. This guide explains the two forms of testing, what BS 8539 requires, how many anchors need testing, and when the test is needed.
Why anchor testing exists
Post-installed anchors, whether mechanical expansion anchors or bonded resin fixings, carry safety-critical loads on facades, balustrades, plant, brackets, scaffold ties and building services. If the concrete is weaker than assumed, the hole was not cleaned properly, or the wrong anchor was used, the fixing can fail under load. On safety-critical work that failure can injure people.
BS 8539 sets out how anchors should be specified, installed and, where necessary, tested, so that the whole chain from design to installed fixing is controlled. On-site pull testing is the part of that chain that verifies the installed reality against the design intent.
Proof testing versus allowable load testing
BS 8539 describes two distinct on-site test regimes, and they answer different questions.
Proof testing, also called sustained or non-destructive testing, applies a defined test load to a sample of working anchors to prove the quality of installation. The anchor is not taken to failure; it simply has to hold the specified test load without excessive movement. This is the common case, used to confirm that fixings have been installed correctly.
Allowable load testing is destructive. It is used where the base material is unknown or no manufacturer performance data exists. Test anchors are loaded to failure so that a safe allowable resistance can be calculated for the specifier. This establishes what the fixing can actually carry in that substrate, rather than confirming a value that is already known.
In short, proof testing checks the quality of installation; allowable load testing establishes performance where the base material or product data is unknown.
How many anchors need testing
Under the Construction Fixings Association guidance that accompanies BS 8539, the sampling rate and the test load are linked. Testing one in 40 fixings allows a test load of up to 1.5 times the applied load, while testing one in 25 fixings allows a test load of 1.25 times the applied load. In both cases the applied load should never exceed the manufacturer’s recommended figure.
The right rate depends on the application and the consequences of failure, and it is agreed with the specifier before testing begins. The point is that a proportion of the working fixings is proof tested to a load safely above their duty, giving statistical confidence in the whole population.
What gets tested
Anchor pull testing applies to a wide range of post-installed fixings, including:
- Mechanical expansion anchors and undercut anchors
- Bonded or resin anchors and threaded studs
- Scaffold ties and anchor ties, tested in line with NASC TG4 guidance
- Cavity wall ties and remedial wall ties in masonry
- Fixings for balustrades, handrails, brackets, plant and facade support
- Fixings into concrete, brickwork, blockwork and stone
When you need it
Anchor testing is typically requested before a safety-critical installation is signed off, when working into an older or unknown substrate with no reliable strength data, when no suitable European Technical Assessment approved anchor is available and a resistance has to be established on site, at handover of scaffold tie or temporary works installations, and on facade retention or remedial wall tie schemes. It is also prudent where installer competence or supervision during fixing was uncertain.
Common questions
What is BS 8539 anchor testing?
BS 8539 is the British Standard code of practice for the selection and installation of post-installed anchors in concrete and masonry. It sets out how anchors should be specified, installed and tested, and it defines two on-site test regimes: proof testing to confirm installation quality, and allowable load testing to establish a safe resistance where no data exists. Testing to BS 8539 gives documented, defensible evidence that a fixing is fit for its intended load.
What is the difference between proof testing and allowable load testing?
Proof testing applies a defined load to a sample of working anchors to confirm they have been installed correctly, without pulling them to failure. Allowable load testing is destructive: test anchors are loaded until failure so that a safe allowable resistance can be calculated. Proof testing checks quality of installation; allowable load testing establishes performance where the base material or product data is unknown.
How many anchors need to be tested?
The sampling rate and test load are linked. Under the CFA guidance, testing one in 40 fixings allows a test load of up to 1.5 times the applied load, while testing one in 25 fixings allows a test load of 1.25 times the applied load, with the applied load never exceeding the manufacturer’s recommended figure. The right rate is agreed with the specifier before testing.
Is anchor testing always required?
No. Where a European Technical Assessment approved anchor has been installed into a known substrate by a trained, supervised installer, BS 8539 indicates that testing may not be required. Testing becomes necessary when the substrate or its strength is unknown, when there is no suitable approved anchor, or when installation supervision has not been assured.
If you need fixings proof tested before sign-off, or an allowable load established on an unknown substrate, our anchor pull testing service brings the calibrated equipment and reaction gear to site and issues full certificates. If your project also involves in-situ ground or working platform testing, our guide on plate bearing tests explains that side of on-site load testing.