BS8539 anchor failure

BS 8539:2012 Code of Practice

BS 8539:2012 and its impact on contractors, installers, suppliers, manufacturers and distributors within the construction industry

In our latest podcast, we catch up with Peter Gordan from RawlPlug UK to discuss the impact of BS 8539:2012. He discusses the standard and offers practical advice for designers, specifier, distributors, suppliers, main contractors, installers and trainers.

What is BS 8539:2012 Code of Practice?

The BS (British Standard) 8539 was published in 2012, adapted and driven forward by the CFA, setting out a standard procedure for the safe selection, supplying, installation and testing of anchors / fixings installed in concrete or masonry.

The purpose of the BS 8539:2012 is to guide designers, specifiers, manufacturers, suppliers, contractors, installers and testers of anchors, to ensure a safe and compliant install. BS 8539 refers to ETA (European Technical Assessment) and recommends specifying anchors within the correct ETA for the given application.

Furthermore, the BS 8539:2012 states that as soon as an individual takes responsibility for selecting the anchor, they immediately become the specifier and therefore liable for any consequential errors.

In reference to the BS 8539, the CFA highlights the following:

“If fully adopted, it will result in a reduction of failures of construction fixings with consequent savings in injuries, deaths and liabilities.” (CFA, 2015)

Top highlights from BS 8539:2012

  • ETA approved anchors should be used where available.
  • The correct anchor must be sourced as specified. If an alternative anchor is proposed, the change management procedure must be followed.
  • Installers must be competent with the anchor installation. They must be supervised and upon completion, the installation should be certified by the contractor’s supervisor.
  • Site tests in accordance with the CFA guidance notes should be undertaken by a competent tester.

Why did BS 8539:2012 code of practice come into effect?

As Peter explains, ”BS 8539 was an adaption of an Irish standard which was brought out after a major fatality onsite”. Some key issues within the construction industry highlighted the need for a British Standard:

  • Specification changes for practical and commercial reasons.
  • There was no set procedure for stakeholders to follow for installing an anchor.
  • Tests were often carried out by the manufacturer in-house, with no independent verification leading to the inaccurate design specification and loading information.
  • Over 80% of drop-in anchors are installed incorrectly.

Who does BS 8539:2012 affect?

The British Standard sets out a step-by-step process involving all stakeholders, including:

  • Designer
  • Specifier
  • Contractor
  • Installer
  • Site tester
  • Manufacturer
  • Supplier

Peter goes onto explain, “Every stakeholder has a part to play in the process of BS 8539:2012. It gives you traceability and a set responsibility within the structure, which means that the end game is to have a safe installation using the correct anchor, as designed and installed to the manufacturer’s guideline.”

How does BS 8539 affect designers, specifiers, contractors, installers, site testers, manufacturers, and suppliers?

We have created a handy table summarising how the BS 8539 guides all of the stakeholders;

RoleWhat BS 8539 states
Designers

Design the complete building which means they have access to all of the information incl. load rating and the substrate. In the M&E industry it is very rare that the designer is the specifier.

The designer should outline the anchor/fixing, drawing on the manufacturer’s description and part code so that the supplier can select the correct anchor.

When selecting an anchor, the following should be considered (which we will go into in more detail later):

·    The substrate that the anchor is being fixed into; cracked/uncracked concrete, block, brick, timber etc. (Clause 5)

·      Can the anchor sustain the load bearing of the application?

·    Environment of the anchor. Will it be outside, inside, humid or not and what finish is suitable? From carbon steel to zinc-plated to stainless steel, to high corrosion resistant materials.

·    Type of installation – flush-fixed or through fixing.

·    Type of anchor – torque-controlled, deformation-controlled, undercut or resin.

·       Approvals – does the anchor meet the ETA approval?

Specifiers

According to BS 8539, any individual within the supply chain of an anchor can be referred to as a ‘specifier’. They select the anchor/fixing.

·   The make, type, ETA number, size and manufacturer reference/order number

·   Instructions for installation

·    Guidance for the installer on what to do if reinforcement is hit when drilling

Contractor

Employs the installers onsite. It is their responsibility to ensure installers are trained.

The contractor should provide the correct anchor as specified. If changing this specification, they should carry out the due diligence to ensure that clause 10 of the change of management procedure is followed. If the contractor has seen that the anchor specified is not the correct one, they should inform the original specifier. The contractor should install the anchor to the manufacturer’s specifications (or training).

Manufacturer

Those that manufacture the anchor/fixing.

The manufacturer should provide:

·   All information for the specifier to select the correct anchor​;

·   Technical catalogues and software;

·   Installation instructions for the installer;

·   Recommended resistance (or appropriate safety factor to allow calculation);

·   Setting details including min. thickness of base material, edge and spacing criteria;

·     Installation instructions and equipment needed.

Supplier

Those that supply the anchor on site

The supplier should provide:

·   Provide the anchor as specified, unless a specific change management procedure has
been followed, such as the load specification
​;

·   Take the opportunity to ensure all associated setting equipment is offered to the contractor such as drill bits, hole cleaning equipment, setting tools, torque wrench etc., so that the installer can install anchors correctly;​

·   Provide installation training or facilitate this being provided by the manufacturer;​

·   Provide guidance in anchor selection;

·   Ensure the change management procedure is adhered to if asked for alternatives

Installers
Individuals that install a fixing/anchor into a substrate onsite

BS 8539:2012 states that anchors should be installed and supervised by competent individuals. BS 8539 defines competent as:

“Suitably trained and qualified by knowledge and practical experience, and provided with the necessary instructions, to enable the required task(s) to be carried out correctly”.

When the anchor is originally supplied to site, the installer should look at the setting tools (e.g. torque wrench, torque specification and set the torque up correctly). The drill diameter, drill depth, recommended torque value and load bearing should also be taken into consideration.

Site testers
Usually a manufacturer or distributor that tests the anchor after installation, as requested by the contractor.

BS 8539:2012 states that testing is not required if an ETA anchor has been used, installed and supervised by competent individuals. ​This means:

·   Anybody carrying out a site test should be qualified by the CFA.

·   Proof testing or allowable load testing CFA guidelines should be followed.

·   Correct reporting procedures as per CFA guidelines should be followed.

 

When selecting an anchor, what factors should be considered?

  • Substrate – the manufacturer should advise what substrate is suitable for that anchor, cracked or non-cracked concrete.
  • Loadings – what load can the fixing take and can the fixing perform to the load requirement? Once again, this would be outlined by the ETA.
  • Environment – is it a corrosive environment?
  • Type of install – is it going to be a through fix or a flush fix?
  • Type of anchorage – torque-controlled, deformation-controlled, undercut/key or resin.
  • Approvals – ETA documentation.

The specifier must understand the difference between substrates, before selecting the suitable anchor

  • Concrete – cracked or non-cracked.
  • Brick – solid or hollow.
  • Timber – laminated engineering timbers are quite common. Note that timber is not covered under BS 8539.
  • Blockwork is becoming lighter and we are hanging heavier loads on them.
  • Plasterboard – plaster also has some quite large loads being used on it. Again, this is not covered under BS 8539:2012.
  • Steel Decking is quite common onsite. If we cannot fix steel decking to the entrant where a lindapter wedge would fit, then we need to drill into the substrate.

How does BS 8539:2012 differentiate between cracked and non-cracked concrete?

Anchors that are qualified to be used with cracked concrete are expected to function reliably, in the expected widths of cracks developed. This is a result of tensile stresses in concrete structures, designed in accordance with BS EN 1992. In the region of an anchor, the concrete might be cracked or non-cracked.

According to the BS8539, you have to assume its cracked unless you can prove otherwise. That’s usually via the structural engineer onsite.

“Cracked concrete can have a 30% decrease in load performance over uncracked concrete. If an anchor is fixed into a substrate it wasn’t designed for, the performance of the anchor can decrease by up to 80%.”

The ETA also looks at cracked and non-cracked approvals, with options 1 to 6 covering cracked and 7 to 12 covering non-cracked.

How does BS 8539 guide the specifier to understand the load rating when selecting an anchor?

Once again, it is the responsibility of the specifier to understand the type of load that is being applied to the anchor. Different factors determine the choice of anchor:

  • Is it static or dynamic?
  • The magnitude of the load.
  • The direction (tension and sheer) of the load.
  • The duration of the load (specifically what load is applied to the anchor).

What role does the environment surrounding an anchor play in selecting an anchor?

Different anchor environments
Different anchor environments

Most internal applications will be zinc plated. For certain applications, for example in a multi-story car park once we remove the walls the environment is altered.

Certain applications such as swimming pools need very careful consideration as the chlorinated environment can induce stress corrosion cracking in some grades of stainless steel.

Anchor selection corrosion
Anchor selection corrosion

The table above illustrates the different corrosion categories and their impact on different environments as outlined in the ISO 9223 classifications.

Anchor installation fail
Anchor installation fail

 

In principle, how does the anchor work to play a part in the selection process?

Flush fix – pre-install anchor into the substrate then apply the fixture afterwards.

Through fix – can be fixed straight through the fixture into the substrate for a quicker install but with less accuracy.

The type of installation will determine the suitability of different anchors.

What type of approvals should be considered when selecting an anchor?

BS 8539 recommends to only specify an ETA (European Technical Assessment) anchor. The ETA refers to a harmonised independent set of tests and standards, adhered to by all reputable anchor manufacturers. The ETA is an independent testing house that tests anchors in different substrates and various loads. The ETA document provides performance figures used for the specifier to make the selection. It is awarded following comprehensive testing against a framework, which measures the functionality of the anchors in a wide range of site conditions.

The ETA contains:

  • Manufacturer details
  • Product name and intended use
  • Manufacturing plant/part number
  • Details of the assessment programme and the performance of the product
  • The control task of the manufacturer, depending on the relevant AVCP systems

As Peter describes, “ETA is everybody’s guarantee of safety.” From a manufacturer point of view, if an anchor goes through rigorous testing and the performance data is independent – it is reliable. For contractors, that provides trust as they have all the correct information to hand.

Examples of tests carried out by the ETA include:

  • Over-torque the anchor
  • Fixing it close to the edge

They then take the mean value of these results and that provides an accurate ETA loading specification.

For a designer or an installer, an ETA verification can help them specify and install the right anchor. There is clear data to refer to. If the installation conditions are as per the ETA test, then that is a guarantee that the fixing will achieve that load value. The ETA supports the quality of the fixing all the way through to the installation.

Do you need an ETA-approved anchor?

BS 8539 guidelines outline that the distributor/supplier must ensure the customer is aware of the setting tools (or accessories) required to be used with a specific anchor.

Take a through bolt – the distributor must make a customer aware that they need a torque wrench in order to correctly set the torque of a through bolt. If they do not have a torque wrench, it is impossible to set a through bolt.

There are three types of torque-controlled anchors. The torque is the measure of how the fixing is going to perform. If you over-torque, stress can damage the anchor, and likewise if you under-torque, it is unlikely you will meet the approved loads outlined within the ETA document.

So, we have gone through the six points of diligence, we have selected the right anchor and we now need to make sure that the correctly specified anchor reaches the site.

  1. The BS 8539 outlines the process for anchor selection.
  2. The designer should outline in the drawing the manufacturers description and part code.
  3. The distributor will then order that part, also checking the dimensions are correct in terms of diameter and length.

Is it not good enough to change the specified anchor to another of similar size and description?

This is where the ETA independent tests are vital, as an anchor is tested on one substrate. The guidance recommends that the anchor can only be installed on the application that it has been tested with. For example, cracked or non-cracked concrete.

If there is a fixing change from one that was originally supplied, you need to make sure the new fixing adheres to that standard. As a manufacturer, we will advise and redesign the fixing and therefore, we become liable. Through this process, you ensure customers don’t use a fixing in the wrong substrate.

How does the BS 8539:2012 affect an installer onsite?

Installers should be competent in the installation of that anchor type. RawPlug and MIDFIX offer installation training and testing, and now MIDFIX offer online training courses through our own Academy (link). Peter points out that for RawPlug, “Toolbox talks are most effective for installers as it reinforces the correct method of installation. This is because we know most bracketry failures are due to the anchor being installed incorrectly”.

Faulty anchor manufacturing.
Now, in my 35 years I have come across that twice. Fixings are a very simple piece of equipment so the amount of safety built into design is 4:1. So, if it is the correct anchor in the correct substrate and it’s been installed correctly, it should never fail.

What causes anchor failure?

Two of the most common failures are:

Resin systems because they haven’t been cleaned out properly, so that is an installation and training issue.

M&E industry and drop-in anchors. As a manufacturer we do a very simple benchmark – we look at the sale of anchors and the sale of setting tools. If they do not match, you know that an incorrect anchor installation is likely to take place. As mentioned before, for a deformation-controlled anchor you need the specific setting tool for that make and size of anchor.

Installation of a fixing is critical; for deformation-controlled anchors, most of them are installed overhead.

The ETA guidelines play a part in aiding installers. Manufacturers of anchors will usually have an indentation mark on them (referred to as a witness mark). Once you install an anchor, it imprints a number of dots on the anchor. Once auditing is carried out onsite after installation, we can simply undo the rod and see if the fixing has been installed correctly.

As an example, from a manufacturer’s point of view, if there is a failure on site and you have not used a torque wrench, then you have not installed the fixing under the manufacturer guidelines. Therefore, the installation is not compliant to BS 8539 standard.

How does BS 8539:2012 code of practice guide on-site testing to ensure an anchor is compliant?

Site testing is covered extensively in BS 8539, and the main criteria is the tester needs to be competent. Now, the only competency is through the CFA, so you need to get a qualification through CFA. There are two levels; there is proof testing and allowable load testing.

  1. Ultimate load testing
  2. Proof testing

Ultimate load testing

  • Testing the substrate is relatively simple to do with lightweight material, but not with more problematic substrates such as a block of beam systems where there is no clear indication of highlighting the capacity of the concrete.
  • This is why it is important that while specifying an anchor, you need to know the capacity of substrate that the fixing will be installed into.
  • Test the amount of load an anchor can take, working from failure down using safety values.

Proof testing (building insurance companies request proof testing often)

  • Has the anchor been installed correctly?
  • A manufacturer may be asked to test five anchors/fixings in one substrate, or to test every 1 in 25 or 1 in 40.
  • If they are flush-fixed (bolt head anchor) or a frame fixing, you simply can’t test the anchor as you can’t attach it.

Ultimately, a proof test just tests the quality of the installation.

There is further guidance from BS 8539:2012 regarding proof testing and this is also highlighted on the CFA website.

  • How many fixings should you proof test?
  • What load should you test to? What is the percentage safety factor and what should it be going to?
  • If you are testing 1 in 40 fixings, you are only allowed a factor of 1.5 times the applied load. The actual applied load must not exceed the manufacturer’s recommended load.
  • If you test 1 in 25 anchors, the guidelines advise the applied load can be 1.25x the specified load requirement from the manufacturer.

Peter states there is a major issue with proof testing:

“It is becoming a bit of a box-ticking exercise or a commercial requirement more than a safe installation issue”

How does a subcontractor prove to the main contractor that all of the anchors/fixings fitted onsite have followed the correct procedure?

If you log onto the CFA website, you can download the right documentation where you can record the anchor the contractor has specified and the installer has installed. It is important that when the anchor is specified in the design, the correct part code is put on the box. Once this is done, anyone can trace the part code back and examine the fixing specification to see if it is different from what was originally specified.

For us (MIDFIX), proof tests are often requested but how important are they?

BS 8539 states that if a specified anchor has an ETA and it has been installed by a competent installer who is supervised, there shouldn’t be a requirement for a proof test. As a manufacturer, we understand that 95% of bracketry failures are caused by incorrect anchor installation, so clearly that is a requirement for the industry. Training installers is a much more important factor, as Peter explains, “if you go onsite and train installers with a tool box talk and a practical demonstration.”

Before a proof test is carried out onsite, what type of information do you require?

Before we turn up onsite to carry out a proof test, we need to know the following:

  • How has the anchor been installed? If there aren’t any witness marks on the anchor, it is likely the anchor will fail the proof test.
  • What torque wrench has been used?
  • What size drill bit has been used?
  • Have the correct setting tools been used?
  • The load requirement that the engineer has put forward, which we will examine.
  • The load requirement against the recommended load, which we will check. As long as it doesn’t exceed that, we will carry out a proof test.
  • Relevant substrate information.

For BS:8539, we have covered the selection process and what is required within that process, how to get that to site (supply) and the install. We have also looked at how crucial training is as well as testing. I think those four main points tend to affect most M&E building services contractors. But is there anything else BS:8539 throws up?

The guiding principle of the BS:8539 is to try and negate any critical anchor failures. As a manufacturer, RawPlug is finding that more and more contractors are trying to implement the standard and ensure they have a fixing plan in place. Most anchor failures cause commercial damage rather than fatalities. If you follow the guidelines and put a stringent process in place, anchor failures are less likely to occur. From the designer to the installer, everyone should follow the practical guidance outlined.

The biggest enemy to the BS:8539 and the implementation of the standard across the construction industry is the following phrase:

”I have always used those fixings and I have always done it that way.”

We have got to try and educate the industry to get away from that mentality.

For a contractor, a good anchor/fixing policy should be put in place for the following four key areas:

  1. Selection process (how do we select it?)
  2. Supply (how do we get it supplied?)
  3. Install (what are we doing about training?)
  4. Finally, what is our testing programme going to be?

Anchors tend not to fail if they have been installed correctly. Safety is built into the design of an anchor and most anchors have a 4:1 safety factor.

In order to change industry perception of anchors, it is essential that all the stakeholders in the chain work together to promote the awareness of correctly specifying, supplying, installing and testing anchors.

For RawlPlug (third largest European manufacturer of anchors / fixings), and for a technical supplier of anchors/fixings (MIDFIX), it is our job to promote the importance of anchor installation through education and training. Peter explains, “there is a DIN standards for metal structures and a DIN standards for concrete structures, but to connect the two together is often left to the contractor or the distributor to advise. That is a strange scenario when you think about how critical it is because anchors hold metal and concrete structures together.”

Both RawlPlug and MIDFIX encourage contractors, designers, suppliers, manufacturers, distributors, installers and testers to examine BS:8539:2012, and to read the guidance and notes on the CFA website. BS:8539 should be the benchmark of quality for installing anchors. If you follow the due diligence correctly, anchors/fixings should never be a headache again.

…………………………………………………………………

This is one example of how incorrect anchor installation can go terribly wrong:

How can MIDFIX help you become BS 8539:2012 compliant?

Extra resources

The CFA (Construction Fixings Association) offer a handy online checklist

The CFA website has a wide range of tools designed to guide contractors through the BS:8539. You can also download documentation, guidance, and notes and I would strongly recommend people to do that.

ETA – European Technical Association guidance and codes

For a complete anchor / fixing policy call, email, or message our customer team:

0115 922 1585

sales@midfix.co.uk

Instantly message our team online (Monday – Friday 7.30am – 5pm)