The guidance within this page is designed to raise awareness of the issues around anchor/fixing compliance in respect of the selection and installation and if followed should ensure a reduction in risk associated with poor selection and installation.
An overview of the following information will be covered in this guide. Jump straight to the relevant section below:
Anchors and fixings are absolutely vital to preventing the collapse of the structure or installation that depends on them. However, with time constraints and supply issues, anchors/fixings and are not given the attention they deserve.
As the construction industry moves towards a tested, traceable and compliant future, there has never been a greater need to understand and adhere to anchor/fixing compliance. Best practice should be followed during the selection, supply, installation, and testing of anchors and each member of the supply chain has their own responsibility.
Many M&E anchors that are supplied to site support overhead mechanical and electrical services, deemed by the Construction Products Regulation’ as ‘safety-critical’. it is therefore important that best practice is followed to mitigate the risk of suspension or bracketry support failure.
The question to ask is:
If challenged, can you demonstrate that the structure you have installed can take the service load applied to it?
If the answer is ‘no’ then it highly likely that stakeholders within the ‘fixings’ chain are not following the necessary guidance. It is currently recommended that the British Standard: BS 8539:2012 Code of Practice should be followed. To save you time we wrote a clear guide helping you navigate BS 8539:2012.
Why are anchors/fixings important?
Within the building services industry fixings are important because they are often the ‘weak link’.
They are often at the interface between parts that are the responsibility of different parties.
They are often sensitive to workmanship
Their design may be complex and poorly understood
They may deteriorate over time and their deterioration may not be easily seen or identifiable.
They may be concealed by finishes or shrouds, which may mask deterioration, poor installation, or even missing fixings.
The failure of one fixing may trigger the failure of another fixing as they take more load, leading to a progressive collapse.
Partly due to their low cost they are often left to the “last minute” before ordering, resulting in very little thought going into the selection process.
Four common misconceptions/mistakes around fixings/anchors
It is quite common to hear misconceptions when it comes to fixings/anchors but those misconceptions must be disproved otherwise the process from selection to installation won’t be as smooth as it could be.
Here are the four misconceptions/mistakes:
Fixings/Anchors are viewed as commodity products, usually left to the last minute and purchased based on cost rather than performance. If you consider that anchors are commonly installed overhead, and these installations fall under ‘safety-critical’ by Construction Products Regulation (CPR) you can see that anchors/fixings must be viewed in a different light.
The phrase “I have always done it this way, so it must be correct” – humans are a creature of habit and changes to how things have been done can cause fear and confusion. If we were to step back and carry out training before we start an installation this will no doubt reduce the amount of potential installer errors and help you to get it right first time.
Traditionally the site team will order anchors based on past experience – unfortunately the reality is not every anchor is the same, each one has different performance characteristics so it is not right to order anchors on past experience. However, the blame must not always fall on the site team, if they have not trained to understand the anchor/fixing selection process, then this will continue to happen.
Assuming you need a pull test – many M&E contractors will assume you need a ‘pull test’ (an over-arching term given to describe either an allowable load or proof test) however, the truth is you may not need it. If the anchor is covered by an applicable ETA and has been installed into a known substrate by a competent installer and signed off by a competent supervisor then no anchor testing is needed (so save your time & money). If you are working on an old building and the design strength of the substrate is not known and anchor installers/supervisors haven’t been trained then you certainly do need to carry out anchor testing.
What is BS 8539:2012 Code of practice?
BS 8539 standard sets out the responsibilities of all stakeholders within an anchor’s supply chain, (manufacturer, designer, contractor, supplier, supervisor, site tester & installer) and clearly outlines best practice for the selection, supply, installation, and testing of post-installed anchors in concrete and masonry. The purpose of BS 8539 is to reduce the risk of safety-critical site failures.
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 on site. 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 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. the 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 carry out a compliant installation.
· 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
Individuals that supervise a fixing/anchor install into a substrate onsite
The supervisor is responsible for signing off an anchor installation prior to the anchor being loaded:
· They should be adequately trained;
· They are responsible for ensuring the specified anchor is the actual anchor being installed;
· They carry out the final check after installation;
· They make sure the installation is done correctly;
Individuals that install an anchor/fixing 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 the 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.
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.
Is BS 8539 applied by law?
The standard represents best practice around anchor/fixing compliance and may be referred to in a court of law in the event of an accident or building failure (CFA, 2020). The stakeholder identified as the ‘specifier’ at the beginning of the anchor selection process, could be liable if an anchor fails.
Best practice for anchor/fixing selection
Anchor selection is the first step towards a compliant installation. To save you time we have put together an anchor selection guide. Listed below are the questions that should be covered when specifying an anchor.
What type of substrate is the anchor fixing into?
What will the applied load be on the anchor/fixing?
What is the environment surrounding the anchor?
How will the anchor be installed?
What is the anchor type?
What approvals are required for the application?
The first factor to consider is the type of substrate that the anchor is being fixed to, at this point it is worth noting that the manufacturer should advise what substrate is suitable for that specific anchor, cracked or non-cracked concrete, brick, steel decking, or blockwork. If the design strength of a substrate is unavailable we must carry out an allowable load test.
BS 8539 is only applicable to concrete and masonry substrates. Below are just a couple of examples of substrates commonly found on-site.
Cracked concrete is basically Concrete under tension usually found overhead, but not exclusively. BS 8539:2012 notes that only cracked approved anchors should be used in this substrate. Therefore, great care needs to be taken when selecting anchors, particularly overhead. If unsure consult with the main contractor or consulting engineer. If still unsure BS 8539:2012 recommends we assume the concrete to be cracked.
Care needs to be taken not to hit the reinforcing bar while drilling. If the reinforcing bar is struck, drilling must stop and advice taken as altering the location or embedment depth can effect the load capacity of the anchor. Remember, reinforcing/tension bars are added for a reason!
This is a popular flooring slab that requires special approvals, especially when fixing overhead. Care needs to be taken to ensure fixing into the correct location on the slab which is into the hollow. This will avoid striking the tension bars located in the webs.
Composite Rib Decking.
A very common decking option. Dedicated fixings using the re-entrant available depending on the decking manufacturer. If these are not available or you need to fix away from the re-entrant this base material lends itself well to several mechanical anchors such as concrete screws.
If an anchor is fixed into a substrate it wasn’t designed for, the performance of the anchor can decrease by up to 80% (CFA, 2020).
What will the applied load be on the anchor/fixing?
In order to select the correct anchor, the applied load must be known. This is the actual load acting on the anchor in a working state. The magnitude, direction, frequency etc, needs to be understood and used in the selection process.
How does environment impact anchor selection?
Often overlooked and misunderstood, the environment surrounding an anchor/fixing plays an important role in the selection process. This is because the atmosphere of an environment over time can impact an anchor/fixing resistance. We have put together a classification guide to help select the correct finish for an anchor depending on its atmospheric environment.
The ISO 9223 classification table below gives an overview of common environments and the appropriate class of anchor finish required.
It is worth noting that particular care needs to be given when looking at high corrosive/risk areas such as swimming pools and tunnels. For instance, when we consider swimming pools, the chlorinated environment affects normal grades of stainless steel impacting load-bearing elements and fixings and anchors, and are liable to fail through stress corrosion cracking.
How will the anchor/fixing be installed?
More relevant to the installer is the type of installation. There are two types of installation.
A preinstalled flush fixing, e.g. deformation controlled anchors (otherwise known as drop-ins, red-heads or wedge anchors).
A through fixing, as the name suggests, the anchor can be fixed through the fixture.
Basic anchor working principles
In order to select the correct anchor/fixing and to carry out a compliant anchor/fixing installation it is important to understand the different working principles. All anchors work with one of the following principles or a combination of them:
Typical anchor fixings used in building services include:
Through bolts & deformation-controlled anchors
Through-bolts and deformation-controlled anchors work through friction and rely on expansion to resist the load applied.
Concrete screws rely on the interlock principle. The undercut created by the flutes creates the resistance required.
Resin anchors, typically used as problem solvers in M&E, rely on a combination of bonding and interlock to achieve the resistance required. It is important to understand how the different working principles of anchor impact the substrate.
What approvals are required for the application?
BS 8539:2012 states an ETA anchor should be used where one is available. We have written a useful A-Z guide on ETA anchors and why they should be specified. An ETA stands for ‘European Technical Assessment’. there are 12 different types of ETA options. In most cases, the testing assessment is carried out when the anchor manufacturer sends an anchor for pre-testing to a harmonised standard. Once the anchor has received its approval, the information within the document can be used by designers to select the correct anchor and installers to provide safe and secure connections on site.
In most cases, the testing assessment is carried out when the anchor manufacturer sends an anchor for pre-testing to a harmonised standard. Once the anchor has received its approval, the information within the document can be used by designers to select the correct anchor and installers to provide safe and secure connections on site.
This information can also then be used by the installer for testing purposes or engineers for creating a design to show proof that the anchor is fit for purpose and can achieve the loads required. It is also an important document when it comes to the supply of the product to site.
What are the benefits of using ‘Approved Anchors’?
Comply with the recommendations of BS 8539 safeguarding the liabilities of the parties involved.
Performance values provided by the manufacturer can be consistently relied upon
All parties to the construction process can be confident in the long-term security of the fixings
Site testing is not required for an ETA anchor where the manufacturer provides data for the substrate in question and the installation is undertaken by competent operatives under supervision.
*It must be noted that in most cases all the information to safely select an anchor/fixing isn’t known, therefore to ensure best practice and to uphold quality management processes it is recommended that an allowable load test on several anchors/fixings into the specific substrate is carried out to ensure the necessary information is known and recorded before any anchor/fixing is specified on-site.
Can an anchor that isn’t ETA-approved be installed?
Yes, if you have carried out the relevant testing to determine the allowable load in that given substrate. However, BS 8539 states that if an anchor is available with an ETA it should be used and for anchor/fixing compliance ETA anchors should be specified.
Best practice for supplying anchors/fixings
Within M&E very few anchors are specified correctly. According to BS 8539: “The correct anchor must be sourced as specified. If an alternative anchor is proposed, the change management procedure must be followed”.
At the end of this chapter you will know the answer to the following questions:
What are the responsibilities of the supplier?
Why would a specified anchor fail to arrive on-site?
What procedures should be carried out if an anchor has ‘broken spec’ and the anchor originally specified does not arrive on-site.
What are the responsibilities of the supplier?
Must provide the anchor as specified unless a specific change management procedure has been followed.
They should 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., in order 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
Why would a specified anchor fail to arrive on-site?
“Site teams tend to select anchors they have always used and procurement teams tend to look at the cost and neither of these have any consideration in a correct specification” – Stevan Grkinic, technical manager
There are several reasons why the anchor specified does not arrive on-site. In some cases, it is down to a stakeholder making that decision due to commercial or supply issues. Either way, the stakeholder that has made that decision becomes the ‘specifier’ and is therefore answerable should any issues arise. As anchors/fixings are relatively inexpensive they are often viewed as a commodity product and in some cases, it is left to a procurement team to source anchors. As stated before, if you are part of the procurement team buying anchors without a specification then you become the specifier.
Under BS 8539 the site supervisor has the responsibility to ensure that all anchors installed are as specified. They also carry the responsibility of checking the correct setting tools have been used, the installers are competent and finally, signing off the install prior to loading.
What procedures should be followed if the anchor specified has not arrived on-site?
According to BS 8539 clause 10 of the management procedure should be carried out by the contractor;
The contractor must ensure that the alternative anchor has been confirmed by the original anchor specifier, who has had access to the original design data. After this, the correct selection procedure as outlined by BS 8539 must be followed and installed to the manufacturer’s instructions.
Best practice for anchor/fixing installation?
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”.
What happens if the installers or supervisors on a project are not trained?
To follow best practice and anchor/fixing compliance it is recommended that all installers and supervisors are trained.
Most site failures are due to incorrect anchor installation. As BS 8539 outlines anchors should be installed by a competent individual. There may be consequences if an untrained and therefore unqualified individual installs an anchor into a ‘safety critical application’.
What is a ‘safety-critical’ application?
If the failure of an anchor could lead to injury or significant material or economic damage to the building, then the situation is deemed safety-critical. With most mechanical and electrical installations being suspended from the building’s ceilings, these are clearly safety-critical, and anchors should be suitably approved and installed.
Best Practice for testing anchors/fixings
In this section we will answer the following questions:
What is anchor testing?
Which anchor tests are recognised by BS 8539?
How do you carry out an anchor test?
According to BS 8539, who is responsible for carrying out an anchor test?
What is anchor testing?
Anchor testing is a process where an anchor/fixing is tested to a designated test load. The performance of the anchor/fixing can then be quantified. Test criteria is defined in Clause 9 of BS 8539:2012.
Which anchor tests are recognised by BS 8539?
In accordance with BS 8539:2012 there are two recognised type of anchor tests;
Allowable load (characteristic action)
Allowable load test
An allowable load test is carried out where the application involved is not covered by a relevant ETA, or the strength and condition of the base material is unknown, with no published data. Without carrying out an allowable load test you can’t accurately determine the allowable working load of the anchor.
Ultimately, a proof test tests the quality of the anchor installation. These tests are usually carried out after the anchor has been installed.
How do you carry out a ‘proof test’?
A test load is applied to the anchor (no more than 1.5 x recommended) and any movement is observed. This type of test only validates the installation.
How do you carry out an allowable load test?
A pre-determined number of anchors are installed into the substrate. The test metre is attached to each anchor, in-turn, and loaded to a pre-determined level. At this point, the readings are recorded. Each anchor is then taken to a failure point and the readings are recorded. Following on all anchor tests, the average value has a safety factor applied, which gives us our new recommended load for this anchor in the tested substrate.
What are the responsibilities of an individual carrying out an anchor test?
For a compliant anchor/fixing installation, BS 8539 outlines the following responsibilities of the tester:
To ensure tests are carried out to the correct procedures.
Where relevant, anchors are installed in accordance with the manufacturers’ instructions, in the correct locations as required by the specifier.
Results are recorded in a full and comprehensive manner and forwarded to whoever requested the tests.
The tester should hold the relevant CFA qualification.
BS 8539 outlines the different types of tests available, how many tests to carry out, what load, and how results should be interpreted.
How do you carry out a compliant anchor/fixing test?
To carry out a compliant anchor test we must refer to the guidance outlined in BS 8539:2012.
Under BS 8539, site tests should adhere to the following guidelines:
Anybody carrying out a site test should be qualified by the CFA (Construction Fixings Association). To carry out a proof test, the tester requires the CFA General Purpose Proof Testing qualification. To perform an allowable load test, the tester has to hold the CFA Advanced Testing qualification.
For proof testing or allowable load testing, CFA guidelines should be followed.
Correct reporting procedures as per CFA guidelines should be adhered to.
Why do anchors/fixings fail?
In this section, we look to answer the following questions.
1.) Who is responsible for a site failure?
2.) How can I reduce the risk of a site failure caused by anchor or fixing?
It is very rare for anchors to fail on their own, due to their inbuilt safety design factor, but if they do it is commonly because of two reasons:
The Construction Fixing Association (CFA) is the primary source of truth for anchor and fixings best practice. Below are just two examples that highlight the failures that can occur if best practice is not followed.
It is important to note that the specifier is liable for any anchor failure that can be proven to have taken place due to incorrect anchor specification. As we have said before, anchor failures rarely occur, but if they do and there is not sufficient evidence of anchor/fixing compliance, showing that the British Standard or robust internal standards have been followed then the specifier can be liable.
How can I reduce the risk of a site failure caused by an anchor or fixing?
As mentioned previously, within the M&E industry it is often the case that anchors and fixings are left to the last minute. Clearly, this does not leave enough time to follow the necessary guidance for anchor/fixing compliance. It is often said that early and continued engagement with the whole of the supply chain at the right stage of a project can help to mitigate the risk. After all, if clear guidance is provided at the very start of a project inside a fixing policy, then this will leave little scope for malpractice.
The amendments to the building safety bill will bring ‘the golden thread’ legislation into practice. Defined by the building regulation advisory committee as; ‘the information that allows you to understand a building and the steps needed to keep both the building and people safe, now and in the future’. This will have an impact on the whole of the anchor/fixing supply chain.
There will be increasing pressure on contractors/project managers to provide evidence that all anchors/fixings supplied on-site are fit for purpose and that there are competent installers trained to carry out compliant installations.
Who else is discussing anchor/fixing compliance/best practice?
Construction Fixing Association
The CFA (construction fixing association) is the primary association that advises on industry best practices. First set up in 1979 its mission is “ensuring best fixings practice” this is achieved through offering support to all stakeholders involved in the “fixings chain” and working with the UK and European bodies to ensure standards are kept up to date. The CFA offers a variety of resources on its website including guidance and best practice around anchor selection, installation, and testing procedures.
Established over a century ago, The Building Engineering Services Association (BESA) core focus is to support its members active in the design, installation, commissioning, maintenance, control and management of engineering systems and services in buildings. They have recently released the ‘TR50’ ‘good practice’ guide for supports and fixings.
The report provides guidance around supports and fixings for the initial design, specification, testing and installation and identifies common bad practices with bracket installation.
As the industry heads towards a tested, traceable, and compliant future, various peices of legislation will put the onus on all the stakeholders within the supply chain to achieve anchor fixing compliance. Overall, legislation can only go so far. For anchors and fixings to be taken seriously, a culture change is required to move away from short-term costs and last-minute decisions to specifying a fixing policy at the very beginning of a project. Only with early and continued engagement can we reduce the risk of site failures and encourage best practice. Fortunately, it seems the industry is moving towards that common goal.