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Written by Hitesh Pattni (North) and Neil Kirwan (South) - Specification Managers in SFS Group Fastening Technology Ltd.
Contents:
The role of the building envelope today is, essentially, exactly the same as it was when people first sought shelter.
Meeting the needs of building occupants is an essential part of building design and construction. It is a major contributor in achieving a robust specification. But the way in which the different fundamental performance elements is delivered has never been more complex.
All of these factors serve to increase the choice of available solutions. They also make it harder to strike a balance of performance through the 'right' combination of choices. Meeting today's performance challenges is hard enough for designers and specifiers, without also thinking about making the building fit for the future - both of which contribute to a specification being robust. This paper starts by looking at the issue of corrosion in building envelope components - what performance gaps might look like, and how to specify with the future in mind. It then moves on to discuss warranties for components and systems, and why manufacturer engagement is so crucial.
Finally, it considers supply chains, and how embracing earlier technical design can help overcome challenges with the availability of solutions.
All of this builds on the issues described in our first four robust specification papers, and complements the other building performance criteria discussed in the fifth and sixth papers in the series.
It reinforces the benefits of creating robust specifications that aim to eliminate performance gaps. It lends weight to the idea of welcoming greater client input. And it serves as a reminder why getting product experts - manufacturers - involved earlier is key.
Performance criteria like thermal performance and fire safety are areas where 'success' can feel relatively intangible and hard to measure. Both depend on many different components being correctly specified and installed in complex building designs that have been properly assessed for compliance.
The performance that's actually delivered may never be properly tested. Only in-use monitoring of the building envelopes can truly assess thermal performance, and depends on a commitment to evaluating the finished building.
Fire safety, meanwhile, can only be tested in a fire - a situation that nobody wants to see.
By contrast, corrosion is a definitive and visible failure of specific components. If it occurs, it is a failure that cannot be passed off as a fault of another product or a different area of design. The corroded component was clearly the wrong component. It's also a failure that, to be addressed, is a likely to have significant practical and financial ramifications. Project location has a significant influence on performance. Within the building envelope, it is critical that correct material grades are used for primary and secondary fixings.
A site within 10km of a coastal area near salt water, for example, that is a corrosive environment, requires components manufactured from A4/316 grade stainless steel (see BS EN ISO 12944-2:2017 Paint and varnishes - Corrosion protection of steel structures by protective paint systems - Part 2: classification of environments for exposure categories and materials that should be used in each). Carbon steel components can suffer catastrophic failure in this industry due to rapid corrosion caused by a galvanic corrosion/reaction (when two metals that are dissimilar are in contact in a corrosive or conductive environment).
A specifier might be aware of location constraints and feel confident in selecting appropriate components across different projects. Here again, though, we must think about planning for the future in order to make specifications as robust as they can be.
Air quality issues have come to the fore in recent years, especially in cities. Government advice published in 2018 cites poor air quality as the largest risk to public health in the UK, and links it to a number of chronic conditions and diseases. And recall how the reduction in air pollution during Covid-19 lockdowns in India gave some people in the north of the country a view of the Himalayas for the first time in their lives. Increasing levels of air pollution in cities - and a failure to get to grips with existing air pollution levels - affects the performance and durability of fixings.
Expecting previously appropriate specifications to still be suitable for city centre locations should no longer be the default approach. Specifiers can engage with manufacturers and establish the appropriate grades of fixings and other components depending on the location of the building envelope. Any such specification is only robust, however, if the components go on to be used on site.
It's essential that contractors and installers work with the project team to understand the importance of maintaining the specification as produced. Product substitutions, especially where the replacement component is not to specification, must not be allowed. They void warranties and, more seriously, can lead to a failure of the façade.
Carbon steel fixings and brackets made by a local fabricator were used on a hotel project in Devon after the contractor changed the specification. Despite the coastal location of the site, the contractor prioritised costs over performance and used the different components to make a saving. The contractor is no longer engaged on the project. Due to the risk of the installed fixings corroding, no other contractor will take on the work without the building envelope being restarted from scratch. The attempted saving on fixings put the client in the position of paying for the building envelope twice just to get the project completed.
It is not hard to understand why contractors are tempted to prose product substitutions that sacrifice lower long-term maintenance costs in favour of immediately lower capital expenditure. Responsibility for future maintenance will likely rest with a different party, so what is to be gained from trying to save someone else money in several decades' time?
That is a little unfair on contractors, of course. Unless the contractor is making a unilateral decision, the designer, specifier and/or client often has to sign off on any suggested alternative. Designers and specifiers are working on behalf of the client, and you would expect clients to prioritise lower long-term costs. Except, we all know that's rarely the case. Whatever the rights and wrongs of it, saving money in the short-term often takes precedence.
Product warranties are designed to provide some reassurance that a certain level of performance will be delivered for a particular period of time. But if you select a series of components that al offer, say, a 25-year warranty, does it automatically follow that the components will work together as you need them to?
Individually-selected components are unlikely to have been tested together, so there's nothing to say what performance they should or will provide in any given build-up. The performance of each separate component is likely to be caveated, due to uncertainty about the performance and installation of other components they directly interact with.
Ultimately, all of this is results in a lot of work for specifiers and clients at any given stage of a project - especially when trying to get written confirmations from different manufacturers regarding product compatibility. That is only made worse when specififers find themselves in negotiation with contractors about alternative solutions.
A reluctance to commit to one specific manufacturers or solution can be understandable, especially if there's legitimate concern that other parties will later 'undo' design and specification work. But nobody understand a component or product better than its manufacturer. By discussing project specifiers with a manufacturer, they can advise on what to look for, and what to avoid, in order to achieve the client's end goal. They can advise on suitable components that will deliver envelope performance - whether thermal performance, fire safety, corrosion, or something else entirely.
For example, they may 'just' recommend that fixings and framing components have the same warranty as the preferred façade panels. Or they may recommend components by particular manufacturers that they know will work as part of the complete build-up.
The 'holy grail' in terms of taking a more holistic approach is a complete system solution. In 2018, Dame Judith Hackitt recommended that a better understanding of product performance within system build-ups was needed. Aiming for system specifications as part of the design and specification process does not mean limiting choice. The manufacturer or supplier of a building envelope system is very unlikely to produce every component themselves, so they must have a pool of suitable components available form partner manufacturers and suppliers.
Specifiers can therefore select from this 'pool' of compatible components, supported by the system supplier to meet the project's needs, all the while being confident that the system performance is backed by testing and certification.
Ultimately, the system and its components should reflect the life expectancy and maintenance expectations of of the client - and a system approach should be the standard way to ensure that is the case.
An SFS Specification Manager was approached by a specifier who wanted to use a façade product where the manufacturer offered a 50-year guarantee.
There was little value in specifying a façade with a 50-year guarantee when fixing and framing components would not be able to provide an equivalent warranty. The Specifications Manager therefore worked with the specifier to establish what performance was really required to meet the needs of the project, and helped to devise a more appropriate and balanced solution.
The primary message of this series of papers is to engage with system manufacturers. As we’ve highlighted consistently, manufacturer engagement can deliver an essential level of support, help achieve robust specifications, and make it more likely that buildings perform as intended. When, though, should that engagement take place?
It can often feel like the only time to engage with manufacturers is during a live project. But during a project is when timescales are most compressed, and when everything is needed urgently at almost every stage. In our view, stage 4 of the RIBA Plan of Work is a particular bottleneck. Typically, the technical design only starts at this point. The people who were involved in the earlier stages are unlikely to have done preliminary technical design, and don’t go on to participate in the subsequent detailing. As a result, it leaves little room for engagement with expertise that would be really helpful.
If a manufacturer is consulted at all at this point, it might be too late for them to offer a solution that the project would benefit from. We’ve all become acutely aware of ‘supply chain challenges’, in all aspects of life. In the current market conditions for construction products, it’s unrealistic to expect that manufacturers and suppliers will have excess stock to fulfil unexpected orders.
Undertaking some technical design at an earlier stage of the project timeline can help with planning, especially on large projects. Some designers and specifiers prefer to maintain an open specification, but shortages of raw materials and stock are affecting all supply chains. There is no reason to expect that to change when global demand for construction materials only continues to increase.
Another option for engagement is outside the project environment. This is a different form of engagement, which is more about having an open dialogue about what support is typically required on projects. It gives the specifier an opportunity to learn more about the capabilities and values of the manufacturer in terms of being able to provide that support. Shared values are an important part of getting the most from collaboration. Integrity and openness can lead to success in any of the performance areas covered in this document.
When there is no live project to discuss then it is obviously difficult to work towards specific solutions. But a mutual understanding of how a better working arrangement can be achieved, and what that can look like, can lead to improved collaboration when another project does start.
An architect and client who had previously collaborated on an award-winning scheme approached SFS with a similarly intricate and complex project. Mirrored glass featured heavily in the design, and the ambitious and high-profile nature of the project meant other parties sought to gain exposure from being associated with it but failed to deliver on their promises.
Multiple glass manufacturers and suppliers repeatedly changed the pricing, supply and general advice they offered to the project team. Despite this uncertainty in the supply chain, SFS proposed a subframe solution and kept the focus on that solution.
Technical issues about the weight of the cladding were brought to SFS’s attention at an early stage, and we provided consistent advice about the subframe, fixings and calculations. This, combined with site trials we carried out, meant the client, architect and contractor could work confidently with different glass suppliers, knowing the subframe solution would perform. The early engagement was supplemented with further advice on site during the construction phase.
Just as no individual specifier can be an expert in all areas of the building envelope, so one document cannot cover all areas of building envelope specification in the necessary level of detail.
This paper is one of a series exploring different areas relating to building envelope specification, and looking at the performance criteria that must come together in order to meet the client’s needs.
Ultimately, we want to show why and how prioritising early engagement on construction projects can lead to better building envelope specifications. Specifications that are robust, and which are the best for the individual project.
It’s no exaggeration that specifiers face a more complex and evolving landscape than ever before. Throughout these documents, we’ll show why the benefits of early specification, based on technical expertise provided by external parties, can far outweigh any potential drawbacks.
Find out more on how SFS UK are working to reduce waste, being more energy efficient and creating a more sustainable future for all by visiting our Sustainability Page here.
Robust building envelope specifications
Paper 7: Corrosion, warranties and supply chain challenges
Contents:
- Introduction: building envelope performance
- Corrosion: clear success or failure
- Corrosion: specifications fit for the future
- Corrosion: case study
- Warranties: thinking about life expectancy
- Warranties: early engagement with manufacturers
- Warranties: case study
- Supply chain challenges: benefits of earlier technical design
- Supply chain challenges: case study
- SFS robust specification
- About SFS Construction UK
Building envelope performance
The role of the building envelope today is, essentially, exactly the same as it was when people first sought shelter.
- Provide protection from the elements
- Offer a view to the outside
- Give occupants security
- Achieve a level of comfort inside compared to outside.
Meeting the needs of building occupants is an essential part of building design and construction. It is a major contributor in achieving a robust specification. But the way in which the different fundamental performance elements is delivered has never been more complex.
- Higher standards and greater expectations
- Compliance with compulsory regulations and voluntary standards
- Globalised supply chains capable of offering hundreds of different types of products.
All of these factors serve to increase the choice of available solutions. They also make it harder to strike a balance of performance through the 'right' combination of choices. Meeting today's performance challenges is hard enough for designers and specifiers, without also thinking about making the building fit for the future - both of which contribute to a specification being robust. This paper starts by looking at the issue of corrosion in building envelope components - what performance gaps might look like, and how to specify with the future in mind. It then moves on to discuss warranties for components and systems, and why manufacturer engagement is so crucial.
Finally, it considers supply chains, and how embracing earlier technical design can help overcome challenges with the availability of solutions.
All of this builds on the issues described in our first four robust specification papers, and complements the other building performance criteria discussed in the fifth and sixth papers in the series.
It reinforces the benefits of creating robust specifications that aim to eliminate performance gaps. It lends weight to the idea of welcoming greater client input. And it serves as a reminder why getting product experts - manufacturers - involved earlier is key.
Corrosion: clear success or failure
Performance criteria like thermal performance and fire safety are areas where 'success' can feel relatively intangible and hard to measure. Both depend on many different components being correctly specified and installed in complex building designs that have been properly assessed for compliance.
The performance that's actually delivered may never be properly tested. Only in-use monitoring of the building envelopes can truly assess thermal performance, and depends on a commitment to evaluating the finished building.
Fire safety, meanwhile, can only be tested in a fire - a situation that nobody wants to see.
By contrast, corrosion is a definitive and visible failure of specific components. If it occurs, it is a failure that cannot be passed off as a fault of another product or a different area of design. The corroded component was clearly the wrong component. It's also a failure that, to be addressed, is a likely to have significant practical and financial ramifications. Project location has a significant influence on performance. Within the building envelope, it is critical that correct material grades are used for primary and secondary fixings.
A site within 10km of a coastal area near salt water, for example, that is a corrosive environment, requires components manufactured from A4/316 grade stainless steel (see BS EN ISO 12944-2:2017 Paint and varnishes - Corrosion protection of steel structures by protective paint systems - Part 2: classification of environments for exposure categories and materials that should be used in each). Carbon steel components can suffer catastrophic failure in this industry due to rapid corrosion caused by a galvanic corrosion/reaction (when two metals that are dissimilar are in contact in a corrosive or conductive environment).
Corrosion: specifications fit for the future
A specifier might be aware of location constraints and feel confident in selecting appropriate components across different projects. Here again, though, we must think about planning for the future in order to make specifications as robust as they can be.
Air quality issues have come to the fore in recent years, especially in cities. Government advice published in 2018 cites poor air quality as the largest risk to public health in the UK, and links it to a number of chronic conditions and diseases. And recall how the reduction in air pollution during Covid-19 lockdowns in India gave some people in the north of the country a view of the Himalayas for the first time in their lives. Increasing levels of air pollution in cities - and a failure to get to grips with existing air pollution levels - affects the performance and durability of fixings.
Expecting previously appropriate specifications to still be suitable for city centre locations should no longer be the default approach. Specifiers can engage with manufacturers and establish the appropriate grades of fixings and other components depending on the location of the building envelope. Any such specification is only robust, however, if the components go on to be used on site.
It's essential that contractors and installers work with the project team to understand the importance of maintaining the specification as produced. Product substitutions, especially where the replacement component is not to specification, must not be allowed. They void warranties and, more seriously, can lead to a failure of the façade.
Corrosion: case study
Carbon steel fixings and brackets made by a local fabricator were used on a hotel project in Devon after the contractor changed the specification. Despite the coastal location of the site, the contractor prioritised costs over performance and used the different components to make a saving. The contractor is no longer engaged on the project. Due to the risk of the installed fixings corroding, no other contractor will take on the work without the building envelope being restarted from scratch. The attempted saving on fixings put the client in the position of paying for the building envelope twice just to get the project completed.
Warranties: thinking about life expectancy
It is not hard to understand why contractors are tempted to prose product substitutions that sacrifice lower long-term maintenance costs in favour of immediately lower capital expenditure. Responsibility for future maintenance will likely rest with a different party, so what is to be gained from trying to save someone else money in several decades' time?
That is a little unfair on contractors, of course. Unless the contractor is making a unilateral decision, the designer, specifier and/or client often has to sign off on any suggested alternative. Designers and specifiers are working on behalf of the client, and you would expect clients to prioritise lower long-term costs. Except, we all know that's rarely the case. Whatever the rights and wrongs of it, saving money in the short-term often takes precedence.
Product warranties are designed to provide some reassurance that a certain level of performance will be delivered for a particular period of time. But if you select a series of components that al offer, say, a 25-year warranty, does it automatically follow that the components will work together as you need them to?
Individually-selected components are unlikely to have been tested together, so there's nothing to say what performance they should or will provide in any given build-up. The performance of each separate component is likely to be caveated, due to uncertainty about the performance and installation of other components they directly interact with.
Ultimately, all of this is results in a lot of work for specifiers and clients at any given stage of a project - especially when trying to get written confirmations from different manufacturers regarding product compatibility. That is only made worse when specififers find themselves in negotiation with contractors about alternative solutions.
Warranties: early engagement with manufacturers
A reluctance to commit to one specific manufacturers or solution can be understandable, especially if there's legitimate concern that other parties will later 'undo' design and specification work. But nobody understand a component or product better than its manufacturer. By discussing project specifiers with a manufacturer, they can advise on what to look for, and what to avoid, in order to achieve the client's end goal. They can advise on suitable components that will deliver envelope performance - whether thermal performance, fire safety, corrosion, or something else entirely.
For example, they may 'just' recommend that fixings and framing components have the same warranty as the preferred façade panels. Or they may recommend components by particular manufacturers that they know will work as part of the complete build-up.
The 'holy grail' in terms of taking a more holistic approach is a complete system solution. In 2018, Dame Judith Hackitt recommended that a better understanding of product performance within system build-ups was needed. Aiming for system specifications as part of the design and specification process does not mean limiting choice. The manufacturer or supplier of a building envelope system is very unlikely to produce every component themselves, so they must have a pool of suitable components available form partner manufacturers and suppliers.
Specifiers can therefore select from this 'pool' of compatible components, supported by the system supplier to meet the project's needs, all the while being confident that the system performance is backed by testing and certification.
Ultimately, the system and its components should reflect the life expectancy and maintenance expectations of of the client - and a system approach should be the standard way to ensure that is the case.
Warranties: case study
An SFS Specification Manager was approached by a specifier who wanted to use a façade product where the manufacturer offered a 50-year guarantee.
There was little value in specifying a façade with a 50-year guarantee when fixing and framing components would not be able to provide an equivalent warranty. The Specifications Manager therefore worked with the specifier to establish what performance was really required to meet the needs of the project, and helped to devise a more appropriate and balanced solution.
Supply chain challenges: benefits of earlier technical design
The primary message of this series of papers is to engage with system manufacturers. As we’ve highlighted consistently, manufacturer engagement can deliver an essential level of support, help achieve robust specifications, and make it more likely that buildings perform as intended. When, though, should that engagement take place?
It can often feel like the only time to engage with manufacturers is during a live project. But during a project is when timescales are most compressed, and when everything is needed urgently at almost every stage. In our view, stage 4 of the RIBA Plan of Work is a particular bottleneck. Typically, the technical design only starts at this point. The people who were involved in the earlier stages are unlikely to have done preliminary technical design, and don’t go on to participate in the subsequent detailing. As a result, it leaves little room for engagement with expertise that would be really helpful.
If a manufacturer is consulted at all at this point, it might be too late for them to offer a solution that the project would benefit from. We’ve all become acutely aware of ‘supply chain challenges’, in all aspects of life. In the current market conditions for construction products, it’s unrealistic to expect that manufacturers and suppliers will have excess stock to fulfil unexpected orders.
Undertaking some technical design at an earlier stage of the project timeline can help with planning, especially on large projects. Some designers and specifiers prefer to maintain an open specification, but shortages of raw materials and stock are affecting all supply chains. There is no reason to expect that to change when global demand for construction materials only continues to increase.
Another option for engagement is outside the project environment. This is a different form of engagement, which is more about having an open dialogue about what support is typically required on projects. It gives the specifier an opportunity to learn more about the capabilities and values of the manufacturer in terms of being able to provide that support. Shared values are an important part of getting the most from collaboration. Integrity and openness can lead to success in any of the performance areas covered in this document.
When there is no live project to discuss then it is obviously difficult to work towards specific solutions. But a mutual understanding of how a better working arrangement can be achieved, and what that can look like, can lead to improved collaboration when another project does start.
Supply chain challenges: case study
An architect and client who had previously collaborated on an award-winning scheme approached SFS with a similarly intricate and complex project. Mirrored glass featured heavily in the design, and the ambitious and high-profile nature of the project meant other parties sought to gain exposure from being associated with it but failed to deliver on their promises.
Multiple glass manufacturers and suppliers repeatedly changed the pricing, supply and general advice they offered to the project team. Despite this uncertainty in the supply chain, SFS proposed a subframe solution and kept the focus on that solution.
Technical issues about the weight of the cladding were brought to SFS’s attention at an early stage, and we provided consistent advice about the subframe, fixings and calculations. This, combined with site trials we carried out, meant the client, architect and contractor could work confidently with different glass suppliers, knowing the subframe solution would perform. The early engagement was supplemented with further advice on site during the construction phase.
SFS robust specification series
Just as no individual specifier can be an expert in all areas of the building envelope, so one document cannot cover all areas of building envelope specification in the necessary level of detail.
This paper is one of a series exploring different areas relating to building envelope specification, and looking at the performance criteria that must come together in order to meet the client’s needs.
- Defining robust specification.
- The problem of performance gap.
- Getting clients active and engaged.
- Early engagement: how do we get more of it?
- Thermal performance and sustainability.
- Fire safety.
- Corrosion, warranties and supply chain challenges.
Ultimately, we want to show why and how prioritising early engagement on construction projects can lead to better building envelope specifications. Specifications that are robust, and which are the best for the individual project.
It’s no exaggeration that specifiers face a more complex and evolving landscape than ever before. Throughout these documents, we’ll show why the benefits of early specification, based on technical expertise provided by external parties, can far outweigh any potential drawbacks.
More information
Find out more on how SFS UK are working to reduce waste, being more energy efficient and creating a more sustainable future for all by visiting our Sustainability Page here.
