Skip to main content

CROSS Safety Report

Inadequate balustrade testing

Report ID: 584 Published: 1 July 2016 Region: CROSS-UK

This report is over 2 years old

Please be aware that it might contain information that is no longer up to date. We keep all reports available for historic reference and as learning aids.

Overview

Concerns are raised about the adequacy of tests being carried out on balustrade systems and the reporter feels the information provided often leaves a lot to be desired.

Key Learning Outcomes

For testing companies and fabricators:

  • Load tests should be carried out in accordance with the testing specification and load test requirements

  • Testing conditions should replicate in service conditions. If these cannot be achieved raise them with the specifier.

For civil and structural design engineers:

  • A robust testing specification can ensure accurate tests are carried out

  • It is good practice to review test reports to ensure compliance with specified requirements such as connection design, loading requirements and serviceability limitations for deflections and finishes

  • Consider attending the load test to ensure the testing procedure is carried out in accordance with the specification

Full Report

Find out more about the Full Report

Our secure and confidential safety reporting system gives professionals the opportunity to share their experiences to help others. If you would like to know more, please visit the reporting to CROSS-UK page.

Designs are made by a reporter's firm for balustrade systems for a number of fabricators. In the course of this work the firm are sometimes asked to comment on proposed proprietary systems. These are often justified by testing and appear to give clients reassurance about the suitability of the product. However, the information provided often leaves a lot to be desired, for the following reasons:

  • The testing may only be up to serviceability loads, and not to ultimate

  • In some cases, the test panel consists of two baluster posts, with a handrail in between, and the barrier loading is applied to the handrail. However, this only tests the baluster posts to half of the true design load, as generally a baluster post will be part of a longer run, and so is loaded from both sides.

  • The test is often with balusters on large concrete bases, away from edges, when in practice expansion or resin anchors will be in close proximity to the edge

The test is often with balusters on large concrete bases, away from edges, when in practice expansion or resin anchors will be in close proximity to the edge

Major differences between theory and test

The suppliers of the products are often vague on what anchors would be suitable. A recent test report has come to the attention of the firm which, on the face of it, appears to be reasonable as it was to establish serviceability, ultimate, and failure loads. However, the results were wildly different from theory.

The post in question showed a serviceability deflection of ~10mm, whilst the theoretical deflection is ~67mm. As the baluster post is a simple cantilever, the reporter would expect the tested deflection to be relatively close to the theoretical. Likewise, the theoretical strength is an order of magnitude lower than that shown by the test. A product may be expected to achieve slightly better strength when testing, as the material strength requirements are lower limits, and the ultimate strength can be twice the design strength.

Should differences be investigated further?

The reporter says that testing should be done with an idea of the sort of result that could be expected (from say experience or calculations). If the result is significantly better (or worse) than expected it is a reason to investigate further.

But in this case, they continue, the testing shows the baluster posts as several times stronger than the theory. It appears to the reporter that there may have been anomalies in the carrying out or recording of the test. This balustrade is being advertised for sale and it is concerning to the reporter that such systems may be specified without proper consideration.

Expert Panel Comments

Find out more about the Expert Panels

Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

Balustrades perform an important safety function. Their stiffness is essential to give a feeling of security and their strength is vital for obvious reasons. In principle, load testing is a good predictor of performance because a calculation is only as valid as the assumptions made. Similarly, a test result is only valid if carried out in conditions that match the installation conditions.

It is certainly possible that the stiffness of ‘non-structural’ items may contribute significantly to performance, say to explain a reduction in deflection. However, it is unsafe to rely on such a benefit unless the basis is understood and replicated in a real-life installation. Designers should review balustrade design to ensure compliance with specified requirements such as connection design, loading requirements and serviceability limitations for deflections and finishes.

Designers should review balustrade design to ensure compliance with specified requirements such as connection design, loading requirements and serviceability limitations for deflections and finishes

It has also been observed that load tests on balustrading is sometimes undertaken on test arrangements bolted down to a robust industrial ground floor slab, whereas in practice the handrail posts may be fixed to a wide variety of construction forms.

The reporter is quite right in that conditions under which test results are conducted must be known before the results are used in actual design situations. Major differences between theory and test should be investigated. As well as structural requirements, all balustrades should prevent people (especially small children) and objects from falling through. CROSS has published several reports on the safety of balustrades. You can search for safety information on balustrades on the CROSS website.

Share your knowledge

Your report will make a difference. It will help to create positive change and improve safety.

Our secure and confidential safety reporting system gives professionals the opportunity to share their experiences to help others.