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Webinar follow up: How to achieve high-performance specifications for structure-borne noise and thermal bridging with minimum mass and materials

Following our webinar with The Institute of Structural Engineers on how to achieve high-performance specifications for structure-borne noise and thermal bridging with minimum mass and materials, we’d like to share the answers to the questions asked during the event.

If you would like to ask our team any other questions, you can email us or call us at +44 161 924 1600.

What was the acoustic specification from Level and how was this translated into the acoustic performance of the bearings?

The acoustic specification was quite complex. So there’s a specification for the through-wall acoustic performance, so that’s through both leaves of the system. That focused on the lowest frequency so there was an insertion loss for 63hz and 125hz, and these were high, so more than 60db of sound reduction.

When you unpacked that specification, then there is also different components, so there was an acoustic requirement for the sealing between the panels and also a dynamic requirement.

And then the last part of it was to control the structure-borne transmission, which is where the bearings come in. For the whole package to work to achieve more than 60db, the insertion loss of the bearing had to be 33db at 50hz, and that’s right on the limit of what is practical.

With the amount of testing and retesting we needed to do, it’s clear we couldn’t have got that level of precision with springs.

Where did the design responsibility for the connections back to the steelwork lie? Did Farrat design everything up to the supporting steelwork and then William Hare’s everything after that?

This connection actually contained three areas for responsibility. Concrete side Expanded/Laing O’Rourke // Bearing assembly Farrat // Structural Steelwork William Hare.

The concrete panel and the stub or halfens channel cast into the concrete were the responsibility of Expanded. The bearing assembly, ie all steel pieces in direct contact with the rubber and the rubber bearings themselves were Farrat’s responsibility

The supporting structural steelwork onto which the assemblies connected were William Hare’s responsibility. Further complications arose on the horizontal top corner of panel connections, where a through bar required two additional steel plates to connect to the steelwork – Farrat supplied these as well as accompanying fixings. We found that colour-coded drawings were key to ensuring the project teams were aware of where one responsibility ended and the next began (for example. all orange items are Farrat, all blue are William Hare etc)

Is there any deviation of the acoustic from the acceptable level? If have what is the remedies action taken?

The original intention was to break down the different components – the bearings, the panels, and the sealants – and have an individual benchmark performance for each of those. It quickly became clear that there was so much variation between the individual panels that this would not be successful.

Instead, the acid test is whether the through wall acoustic performance met the requirements, and then we took every panel in turn and looked at the composite effect of the performance of each of the bearings in each of the directions.

There are occasions where, because we were assessing the insertion loss across the spectrum, narrowly we weren’t meeting our ambition for sound insulation, and then we’d have to make the decision on whether that mattered or not. Sometimes it did and then we’d have to go back and redesign. Sometimes it didn’t, and the reason it didn’t is that because of our models, we could assess the significance to the surrounding area of one bearing or panel.

Something to add is that we were able to engineer a much better seal between panels than we were expecting, so that gave us some ‘credits in the bank’. We could then use those ‘credits’ for if a bearing was not performing as well as we would like. My advice to anyone doing a project such as this in the future is to aim to get those ‘credits’ so you have that flexibility.

Was there a modal response design of the shell? And did it impact any parts of the design?

Yes – we had to consider modal performance of the frame and panels simultaneously.

What was the most challenging issue faced at the construction stage? i.e. out of tolerance positioned bearing?

Specific to our assemblies, vertical positional tolerance caused a number of headaches. With most bearings acting in pairs, if one was even 5mm higher than its partner, it would experience higher deflection by trying to take more than its share of the load.

As such all locations had a healthy allowance for localized packing below the assemblies – to ensure both partners were perfectly leveled.

We also found that rotation caused some issues, this was due to tolerance stack-up. For example in some locations both concrete and steel were slightly off perfect 90° angles, but still well within the project tolerances.

However when combined this meant our connection was facing options beyond expectation (for example 3° + 4° gives an actual 7° misalignment between our top and bottom assembly plates, which had the potential to create pinch points in our design. These issues were resolved through the use of location-specific angled packs, to give our assemblies parallel top and base plates.

None bearing specific, the Plane 04 face of the theatre faced significant challenges during construction, due to a lack of crane access beyond the overhang formed by the steel frame above.

In the end, a custom-built frame was produced to allow the concrete panels to be maneuvered into place on the theatre while hanging from a crane above, a significant site challenge overcome by brilliant work from William Hare.

Do you have any thermal information available on the Falcon units, ie psi-values, or a calculated thermal conductivity equivalence that can be used in a 3D thermal model?

Yes, we have been given detailed drawings specifying dimensions and thermal conductivity, this is crucial for bespoke analysis. When we build the thermal models, using the given information, we can deduce a psi value using standardized assumptions taken from the international standard 10211.

The psi value is between 0.3-0.6 W/mK depending on prescribed conditions and thermophysical properties (which dictate the U-value [W/m2K]). We are running various scenarios, using 3D FEA, to inform the development of the product.

Are there any specific solutions for steel to rubble stone, ends in walls and horizontal wall connections?

It’s most likely there could be a solution, however, we have yet to see never Steel-to-Stone (Rubble). Steel-to-Concrete is common and we are now seeing more Concrete-to-Concrete such as in our Falcon solution. If you have a specific project in mind get in touch with the team at Farrat and we’d be interested to hear more about it.

Challenge our engineers

Challenge our engineers to ensure the efficiency and safety of your projects. Email us or call +44 161 924 1600 to talk to the team.

More about Acoustic Isolation in Concert Halls and Theatres.

More about Building Vibration Isolation.

More about Structural Thermal Breaks.

Addressing climate injustice with smarter building design

Climate change continues to be one of the most pressing issues of our day and all industries are going to need to make significant changes to challenge the irreparable damage to our world that could continue to be caused.

However, there is a strong argument that it is those in more developed countries should be working hardest in order to dramatically reduce the impact they are currently having and look to undo as much of the damage already done.

As a result, a historic deal has been struck at the COP27 summit that will see ‘richer nations’ pay ‘poorer countries’ for the damage and economic losses caused by climate change.

Climate injustice around the world

Nearly three-quarters of all excess emissions come from the US and the EU alone. The US is responsible for 40% of all excess emissions with the EU slightly behind on 29%. Latin America, Africa, the Middle East, and Asia combined are only responsible for 8% of excess emissions, and yet these are often the geographic regions that are feeling the repercussions of climate change the most. (Source: The Structural Engineer August 2022)

The most recent example of this is the deadly floods in Pakistan. Pakistan is reported to have received more than 3 times its usual rainfall in August, making it the wettest August since 1961. These floods have destroyed 1.7 million homes, and nearly 1500 people lost their lives. Whilst the region has been subject to monsoons before, studies have shown that climate change could have increased the most intense rainfall over a short period in the worst-affected areas by about 50%.

This region being so significantly negatively impacted by the effects of climate change despite contributing so comparatively little is the very definition of climate injustice.

A change in approach to building design to reduce climate injustice

When looking at the fastest-growing economies in the world, they are mainly developing nations such as India, Bangladesh, and Rwanda. However, when you look at some of the biggest construction projects in the world, 7 out of 10 of the largest construction projects in the world being started, worked on, or completed in 2022 are in developed countries.

Get in touch: Challenge our engineers to ensure the efficiency and safety of your projects. Email us or call +44 161 924 1600 to talk to the team.

The European construction sector is expected to grow by 2.5% in the same period.
As the built environment continues to grow in the developed world, the construction industry needs to create effective collaborations between architects, contractors, developers, and project stakeholders in order that buildings are designed with environmental factors in mind.

Insulation

Through the cost-of-living crisis partially caused by the issues in Russia and Ukraine, there are many easy-to-access statistics on how much insulation can save you in terms of money spent on energy bills – the Environmental Protection Agency in the US state that the average homeowner can save 11% of total energy costs by adding insulation.

The cost of bills might be a driving factor for individuals but the reduction in the use of energy means fewer carbon emissions which can only have a positive impact on the environment and decrease the need for reparations in the future.

The phrase ‘insulation’ make bring to mind domestic solutions such as cavity wall and loft insulation but in fact, when done efficiently, insulating buildings starts at the building design stage with the choice of building materials and steps taken throughout to reduce the transference of heat/cold between inside and outside.

In addition to the building materials selected for walls and the types of windows and doors specified, it has long been recognised that thermal bridges within building envelopes can cause problems of heat loss, leading to poor energy performance.

The use of structural thermal breaks between steel and concrete protruding through building envelopes will ensure efficiency in this area. This also includes finer structural details such as façade system supports, balcony attachments, data centre substructures, and rooftop plant installations.

Sustainable building materials

According to the November 2020 National Infrastructure Strategy in the UK, there are six overarching recommendations where the action taken now will result in rapid decarbonisation of the construction sector. One is that current design and performance standards should be updated to enable more holistic design approaches that support the efficient design and reuse of materials.

This was echoed in a report by the Royal Academy of Engineering on ‘Decarbonising Construction’, which stated that using sustainable materials as standard and low-carbon procurement were two key vital aspects in achieving net-zero transformation in the construction sector.

Current end-of-life scenarios for three of the most common construction materials; concrete, timber, and steel are shown below.

Whilst steel production is currently a source of greenhouse gas emissions, a revolution in steel production is within reach by reusing or recycling it as standard. Reusing it lends itself to modular design where old materials can be made into aspects of a new building, which would also use less energy than recycling it.

The downcycling of concrete – crushing and using it in different applications – is a common practice in the construction sector. Currently, aggregate made from downcycled concrete accounts for 6% to 8% of aggregate use in Europe. Maintaining and expanding this practice could prevent concrete from going into landfill, but doesn’t influence the emissions from cement production since it meets the demand for a different application.

Overall reusable materials such as steel are ideally placed for reducing emissions, and use of steel is on the rise. In 2021 the use of structural steelwork in industrial buildings increased by 16.4% and by 10% for offices with further growth predicted, showing an appetite for steel as a sustainable and reusable material.

Combining insulation with sustainable building specification

Where sustainable and environmentally friendly building design collaborations will be most likely to succeed is with a smarter design made up of energy efficiency, reusable material specification, and an approach to insulation that goes beyond what is the bare minimum.

This is key for buildings designed for developed countries, but ‘the West’ can also lend their skills and technology – and provide education – to construction in developing countries in order that they can get commercial structures and residential developments right first time.

This will ensure they avoid a future situation that countries like the UK find themselves in currently, where they are looking at millions of buildings dating back to before the industrial revolution that need retrofitting with insulation to meet the ideal standards that could be achieved with the initiative and funding.

Summary

Engineers, architects, and specifiers are facing a huge challenge in taking a holistic approach to sustainability to help tackle climate change and tackle climate inequality that is plaguing the world.

This isn’t something to worry about in the future. With developing countries already feeling the force of environmental change and lives already being lost, climate inequality caused by construction needs our full attention now before the effects are made worse and spread further still across the world.

About the author

Chris Lister BA(Hons) DipArch – Commercial Manager Structural Thermal Breaks

Chris Lister is the Commercial Manager for Farrat Structural Thermal Breaks and the Northern Region Chair of the British Construction Steel Association BCSA.

Having studied both Engineering and Architecture he has worked exclusively in the construction and building product design sector. Chris heads the development of Farrat Structural Thermal Break products and Facade Design Solutions.

He is a passionate contributor to the global discussion on fire safety in high-rise structures and building physics research. An advocate for achieving the highest level of energy efficiency Chris is the Farrat Lead on our new product development Project “Falcon” aiming to design out bouncy balconies

Thermal break materials with Farrat

Farrat’s Structural Thermal Breaks are an essential component for energy-efficient buildings. If you would like to learn more about the integration of thermal breaks in structural connections, contact our Structural Thermal Break team by email, call us at 0161 924 1600 or fill in the contact us form.

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Chris Lister Farrat

Multi-screen cinema with market-leading acoustic isolation wins Best Project in Leisure award

The new multi-screen cinema in Glasgow – with acoustic isolation carried out by Farrat – has won the Best Project in Leisure award at the first-ever Scottish Structural Awards.

The new Scottish Structural Awards is set to celebrate the best structural projects completed over the last two years by Scottish design engineers with a strong focus on sustainability and environmental responsibility as well as innovative building design.

Farrat are proud to share that the winner of the ‘Best Project in Leisure’ award – the new Vue International multi-screen cinema at the St. Enoch shopping centre in Glasgow – is one that we have contributed to, both manufacturing and installing our CineFLOOR MAX acoustic isolation solution.

The new cinema is part of a redevelopment project that includes 100,000 sg ft of retail and leisure space. Efficient and effective acoustic insulation in multipurpose leisure developments such as these is key to ensuring that cinemas with state-of-the-art sound can co-exist seamlessly alongside other leisure facilities.

“Being involved in a project acknowledged in these brand-new awards is very rewarding,” states Neil Wilson, Senior Project Delivery Manager at Farrat.

“Following the pandemic, the film industry’s recovery is growing, and we hope that by continuing to work with organisations committed to creative building design, efficient use of space, and the best possible acoustics and acoustic insulation, we can be a significant part of this rejuvenation.”

Acoustic Isolation with Farrat

With over 60 years’ experience in acoustic isolation, our engineers are on a mission to address the cinema market’s most demanding acoustic challenges.  Contact our Acoustic Isolation team by email, call us on 0161 924 1600 or fill in the contact us form online.

Challenge our engineers to meet your project’s needs. Contact our Acoustic Isolation team by email, call us on 0161 924 1600 or fill in the contact us form online.

Mixing timeless architecture and energy efficiency with fire rated structural thermal break material Farrat TBF

22 Ropemaker is set to be a brand-new comprehensive development in London, made up of over 420,000 sq ft spread over 27 stories. Within close proximity to several of the key London Underground stations, this commercial building has been designed with well-connected and forward-thinking businesses in mind. As a result of this, sustainability and energy efficiency are driving factors in material-specifying decisions

The challenge

The rise in energy costs across the UK means that energy efficiency is a growing and more pressing consideration for businesses looking for new premises.

In addition to the cost of gas and electricity bills, energy efficiency is important to businesses looking to ensure they are minimising their carbon footprint wherever possible and to be able to demonstrate that.

The number of outside spaces including balconies and roof terraces, as well as the creative use of façades in the classic design of this building, meant that to maximise energy efficiency without compromising on structural integrity Structural Thermal Breaks would need to be used across the entirety of the façade at multiple structural connection scenarios

Another key challenge in any high-rise building development is fire safety. Since the Grenfell disaster where 72 people died and another 70 people were injured when a 24-story block of flats burnt down, the use of fire-safe materials has been at the front of both residents’ and developers’ minds – especially in high-rise buildings – as has the new legislations being rolled out across England and Wales.

Challenge our engineers to ensure the efficiency and safety of your projects. Email us or call +44 161 924 1600 to talk to the team.

The recently enacted Building Safety Act 2022 has been created to address an identified lack of oversight, as well as to clarify the roles and responsibilities within the construction and maintenance of ‘high-risk development’ (buildings that are at least eighteen metres tall or at least seven floors, containing two or more dwellings.)

The level of accountability and scrutiny that this act drives further increases the focus on and demand for fire-resistant materials wherever possible.

The solution

Farrat TBF was the fire-rated structural thermal break material selected by façade specialists Josef Gartner GmbH to prevent heat transfer through beams where the external building aspects meet the interior.

Farrat TBF is an A2,s1,d0 rated non-combustible structural thermal break material that can maintain optimal structural performance at temperatures at 550°C and maintain integrity beyond 1000°C In addition to being the leading fire-rated thermal break solutions; exceeding all current fire regulatory requirements for buildings above (and below) 18m, Farrat TBF also provides high-level thermal performance to solve structural thermal bridge issues.

The outcome

“High-rise building design that takes into account both energy efficiency and fire safety is set to be the norm in cities around the world, but is especially poignant in London,” states Chris Lister, Commercial Manager of Structural Thermal Breaks at Farrat.

“To see Farrat TBF being used in a building designed to ensure the comfort and safety of those occupying it as well as such as a strong focus on wellbeing with the use of outside space is hugely rewarding.”

Fire-rated thermal break materials with Farrat

Farrat’s Structural Thermal Breaks are an essential component for energy-efficient buildings. If you would like to learn more about the integration of thermal breaks in structural connections, contact our Structural Thermal Break team by email, call us on 0161 924 1600 or fill in the contact us form below.

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The significance of Structural Thermal Breaks in high rise fire design and Building energy performance

Since the tragic circumstances of the Grenfell disaster, designing for fire and construction material choice in all its facets has become a focus of design teams across the world. In balance, the global demand for energy efficiency and net-zero carbon pulls designers in an equally important direction.

Farrat recently held a webinar to explore these issues. Thank you to all those that attended, if you would like a certificate of attendance please email ld@farrat.com with the name you joined the webinar with.

If you would like to access the slides from this event Click Here.

Farrat TBF – surpassing structural and fire resistance requirements

Farrat unveiled the market’s first A2 Fire Rated Structural Thermal Break ‘Farrat TBF’ in 2019, following 12 months of research and development in consultation with Salford and Manchester Universities, material scientists, and specialist raw material producers.

Farrat TBF is an A2,s1,d0 non-combustible Structural Thermal Break material designed to maintain full structural integrity in the event of a fire.

Alongside its limited combustibility, the new Farrat TBF material stands alongside the market’s best performing thermal insulators, with very high compressive strength and low thermal conductivity – preventing thermal bridges from forming between structural connections and mitigating against the risk of condensation, mould, or corrosion.

In 2020, following further investigation and enhancing the performance criteria, Farrat TBF met and exceeded the stringent structural requirements of two hour/ 550⁰C fire resistance, and in 2021 Farrat TBF was certified by the BBA, alongside our other market-leading thermal break products; Farrat TBK and Farrat TBL.

Download the datasheet for more information about Farrat TBF

Case study

Working with an international design team to achieve the highest energy efficiency & sustainability standards, for an exciting new high-rise tower located in Morocco’s City of Light

Set to be the tallest building in Africa at 250-metres with 55 stories, Mohammed Tower IV is a new high-rise tower designed by Rafael de la Hoz & Hakim Benjelloun to resemble a rocket on its launch pad. Farrat TBF was selected as the optimal structural thermal break material for extensive use across the façade connections of Mohammed Tower, to prevent heat transfer through steel beams where the external building aspects meet the interior. Read the full case study.

To talk to Farrat about our structural A2 Fire Rated Structural Thermal Break ‘Farrat TBF’ get in touch, or find out more by downloading the datasheet.

Mohammed Tower image
Farrat TBF

What is Chatter_Detect? How we’re improving the quality of strip metal by eliminating chatter marks.

In the sheet metal industry chatter marks on the finished metal product can cause significant issues for customers. Marks on metal strip affect the quality of the product in industries such as automotive and can-making and can often lead to finished coils being rejected by the customer. These marks are often invisible to the naked eye but can show up further down the line, for example when a car door is being painted.

One of the main causes of chatter marks on finished metal is marked rolls being used in the mill. This is where the rolls used in the rolling mills arrive with chatter marks caused by the roll grinding process. As with the finished product, the chatter marks on the roll can often be invisible to the naked eye, meaning that the grinder operator has no way to tell whether the rolls have chatter marks or not before they are sent to the mill.

Example of chatter marks on a finished strip of metal from a rolling mill
Example of chatter marks on a finished strip of metal from a rolling mill
Example of a roll that has chatter marks which are invisible to the naked eye
Example of a roll that has chatter marks which are invisible to the naked eye

An ideal solution to this problem is this innovative Chatter_Detect system. Since Farrat’s acquisition of UniVib – a specialist industrial vibration consultancy – in 2020, Farrat has made use of Chatter_Detect technology in a wide range of businesses around the world.

Chatter_Detect is a post-process roll inspection system that detects chatter marks that may have been ground onto the surface of finish-ground rolls by vibrations generated during the grinding process.

It uses a high-resolution, non-contact capacitive sensor that can detect invisible chatter marks which can be small but still significant enough to affect the rolling process and cause chatter on the strip.

The Chatter_Detect system can identify the pitch and depth of the chatter marks and also enables the operator to set a depth threshold level, so that marks that are not significant enough to affect the rolling process, don’t trigger the Chatter_Detect alarm.

Chatter Detect system
Chatter Detect system

The Chatter_Detect system has helped some of the biggest names in the sheet metal industry ensure that only chatter free rolls are sent to the mill and quality is maintained throughout the roll grinding process.

chatter detect

Chatter_Detect with Farrat

If you’re looking to monitor floor vibration levels or for a bespoke, tailored vibration isolation solution that optimises performance, efficiency and accuracy of industrial machinery within an industrial or production setting, get in touch with the team at Farrat for more information.

Evaluating the reuse of existing isolated foundation systems for upgraded plant machinery.

Manufacturing businesses are often looking for ways to minimise their waste in terms of spoilage or rejection by upgrading to newest state of the art machinery. However, manufacturers could be thinking beyond their actual products and the items used on-site, to re-evaluate if they could be reusing manufacturing equipment and infrastructure. In doing so they could not only reduce the need for new installations but also make significant financial savings.

Reusing existing isolated foundations for new machinery in a beverage can plant

Isolated foundations and other vibration control solutions are frequently used in factories and manufacturing plants to reduce levels of transmitted vibrations that affect the health and safety of workers as well as the accuracy and productivity of surrounding machinery and activity. This is especially true in beverage can manufacturing plants where heavy impact machinery such as cupper presses and bodymakers can generate excessive dynamic loads.

A recent project for Farrat in Cairo, Egypt, was to establish whether a pre-existing isolated foundation could be used for new manufacturing equipment. A member of our Industrial Vibration Isolation team made a visit to the factory to assess the level of performance of some existing isolated foundations that are currently supporting bodymakers.

These results have been used to determine if a spare isolated foundation installed 10 years ago and presenting the same design could be used to support new machine in the near future.

Not only would this enable a significant financial saving but would also negate the need for digging out new isolated foundations and the associated materials and disruption. In addition, repurposing something already in place is a more environmentally friendly option for a business that creates a product that can be recycled an infinite number of times.

Engineering led vibration and noise measuring and analysis

To determine whether existing infrastructure could be used for effective vibration control, contact the Farrat vibration and noise consultancy team, who work with a wide range of clients across the manufacturing sector, using on-site portable instrumentation for vibration measurement and vibration analysis around the world.

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Upcoming Webinar: The significance of Structural Thermal Breaks in high rise fire design and Building energy performance

Farrat is partnering with the Institute of Structural Engineers this June to produce a new webinar on the significance of Structural Thermal Breaks in high rise fire design and building energy performance. This webinar is ideal for designers, architects, engineers, and specifiers, who are looking to go beyond the standard in fire design and energy efficiency.

Since the tragic circumstances of the Grenfell disaster, designing for fire construction material choice in all its facets has become a focus of design teams across the world. In balance, the global demand for energy efficiency and net-zero carbon pulls designers in an equally important direction.

This webinar with Farrat looks through the lens of Structural Thermal Breaks at the multi-role demands of building components to deliver best-in-class performance in sustainable credentials and building physics without compromising on fire safety.

The webinar will assist designers in understanding:

  • The latest developments in UK Fire and Building Safety regulations
  • Current requirements for specifying safety-critical building products
  • Up to date thought on the UK standards for construction material performance information
  • Current direction and time frame for Structural ‘Green’ Steel and the journey towards Net Zero
high rise fire design

Date: Tuesday 21st June

Time: 9 – 10am BST

Presenter: Chris Lister. Commercial Manager – Structural Thermal Breaks

Chris Lister is the Commercial Manager for Farrat Structural Thermal Breaks and British Construction Steel Association BCSA National Council Member. Having studied both Engineering and Architecture he has worked exclusively in the construction and building product design sector, in both senior technical and commercial roles.

At Farrat he is principal in the development of Farrat Structural Thermal Break products and facade design solutions. He’s a passionate contributor to the global discussion on fire safety in high-rise structures and building physics research and advocate for achieving the highest level of energy efficiency in building design.

Chris is a dedicated father, diehard Rugby player, and fair-weather motorcyclist.

The top 5 questions asked by engineers when specifying structural thermal breaks

The ability to transmit structural loads whilst addressing thermal performance through a building envelope has long been a difficult balance for building designers. The weight of decision has often fallen on the side of the structure, with the importance of structural integrity winning out against the impact of structural members piercing the thermal envelope.

However, as the energy demands of new and retrofit buildings have grown, so have the requirements to minimise that energy usage and the potential of issues such as thermal bridging.

This has resulted in greater levels of insulation in planar elements of a building envelope, leading to more noticeable and detrimental effects of those ‘hard to treat’ details such as structural penetrations. Add to this the need to achieve compliant critical internal temperature factors for the avoidance of unsightly or harmful mould growth and mitigating thermal bridges in a building envelope moves higher up the list of problems to solve.

Equally, the growing influence of fire design on structures has also led to the requirement for enhanced performance criteria of building materials in relation to fire that are incorporated into the building envelope. To address this imbalance, new building materials and methods of thermally breaking structural connections, such as steel beams and balcony connections, have been developed.

In the below guide, we address the most frequent questions asked by Structural Engineers when specifying Farrat Structural Thermal Breaks.

1. Which Farrat Structural Thermal Break material should I specify?

Farrat Structural Thermal Breaks take the form of flat plates of any dimensions, which provide Architects with complete design freedom and Structural Engineers the capability to design to standard codes, with a simple configuration.

Farrat offer three independently tested Structural Thermal Break materials, which are designed to balance high structural performance and low thermal conductivity:

  1. Farrat TBK (Yellow) is most specified across typical connection details, with high compressive strength (312MPa fck) and the best thermal performance in the range (0.187 W/mK).
  2. Farrat TBF (silver) is the optimum material when fire performance is a consideration, such as within high-rise buildings, due to its high compressive strength (355MPa fck) and low thermal conductivity (0.2 W/mK) performance characteristics, supported by an A2, s1,d0 Non-Combustible Classification.
  3. Farrat TBL (Black) is the favourable material when structural loadings and requirements for thermal performance are lower, and budgets are constrained, offering medium compressive strength (89MPa fck) and thermal conductivity (0.292 W/mK) performance characteristics.

2. How do I design connections incorporating Farrat Structural Thermal Breaks?

A breakdown of what to consider when designing structural steel connections is contained within the Farrat Structural Thermal Break Technical Guide and supporting SCI, Steel Construction Institute assessment document.

As an overview:

  1.  Structural Thermal Break plates should be considered as a “pack” in terms of connection design.
  2. All Shear forces need to be accommodated by the connection bolts. As a result of the multiple layers in the connection the grip length of the bolts may be significantly increased, it may also be necessary to reduce the anticipated shear resistance of the bolts in the connection.
  3. Reference should be made to BS EN 1993-3 1-8: 2005 Eurocode 3. Design of steel structures.

Example screenshots adjacent are taken from the Farrat extension for Tekla Structures that creates Farrat Structural Thermal Break connection plates. The component automatically takes the plate dimensions and holes of the plate it is fixing to.

3. Can Farrat Structural Thermal Breaks support the loads I am designing for?

The exact physical and mechanical properties for Farrat Structural Thermal Breaks are contained in the Farrat Structural Thermal Break Technical Guide.

As a quick guide:

  1. Farrat TBF and Farrat TBK materials offer compressive strength comparable with Steel.
  2. Farrat TBL has a compressive strength greater than Concrete.
  3. Structural Thermal Break plates in a connection should only be designed to resist compressive forces.
  4. Consideration should also be taken of compressive creep. Farrat materials are formulated to resist long term creep, but this element should be factored into any design.
  5. Many materials which exhibit good thermal properties have poor long term creep profiles.
  6. Reference should be made to BS EN 1993-3 1-8: 2005 Eurocode 3. Design of steel structures.

4. What is the friction coefficient for Farrat Structural Thermal Breaks?

The coefficient of friction of a thermal break plate is not a relevant property for the structural design of connections with non-pre-loaded bolts.

Whilst figures for frictional resistance of Farrat Structural Thermal Breaks can be obtained, it will differ depending on the material with which it is in contact and should be treated with caution when designing connections involving Preloaded or TCB bolts.

5. Will Farrat Structural Thermal Break plates achieve a 120-minute fire rating?

Structural steel connections that require a 120-minute fire rating will typically need to be protected with either an intumescent coating system or a fire protection board. In all situations, the Structural Thermal Breaks should receive the same level of protection as the steel.

However, Farrat TBF Structural Thermal Breaks have been tested unprotected in fire conditions, in structural steel connections, to temperatures more than 1000°C for 120 minutes and maintained structural integrity.

Different building types and legislators have differing technical and regulatory requirements for fire design, but if fire is a concern that requires addressing, then the use of non-combustible thermal breaks is one way to mitigate that risk.

Farrat TBF fire test
Farrat TBF fire test

In summary, when designing for Structural Thermal Breaks:

  1. Check that the chosen material is independently verified to resist the applied compression forces, with an appropriate safety factor applied to determine design loading.
  2. Check that any additional rotation due to compression of the thermal break plate is acceptable.
  3. Check the shear resistance of the bolts is acceptable given that there may be a reduction due to the use of packs and larger grip lengths.

If using Pre tensioned bolts:

  1. Check the slip resistance of the connection considering the coefficient of friction and the number of surfaces.
  2. Check the thermal break plate can resist the local compression forces around the bolts.

Where fire performance is concerned:

  1.  Consult with Farrat for the correct specification of fully tested and certified materials.

 


 

For more information on integrating thermal break solutions into typical, or bespoke, structural steel connections, visit our Structural Thermal Break hub or one of our dedicated portals:

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The top 5 questions asked by architects when specifying structural thermal breaks

The ability to transmit structural loads whilst addressing thermal performance through a building envelope has long been a difficult balance for building designers. The weight of decision has often fallen on the side of the structure, with the importance of structural integrity winning out against the impact of structural members piercing the thermal envelope.

However, as the energy demands of new and retrofit buildings have grown, so have the requirements to minimise that energy usage and the potential of issues such as thermal bridging.

This has resulted in greater levels of insulation in planar elements of a building envelope, leading to more noticeable and detrimental effects of those ‘hard to treat’ details such as structural penetrations. Add to this the need to achieve compliant critical internal temperature factors for the avoidance of unsightly or harmful mould growth and mitigating thermal bridges in a building envelope moves higher up the list of problems to solve.

Equally, the growing influence of fire design on structures has also led to the requirement for enhanced performance criteria of building materials in relation to fire that are incorporated into the building envelope. To address this imbalance, new building materials and methods of thermally breaking structural connections, such as steel beams and balcony connections, have been developed.

In the below guide, we address the most frequent questions asked by Architects and Building Envelope specialists when specifying Farrat Structural Thermal Breaks.

1. Which Farrat Structural Thermal Break material should I specify?

Farrat Structural Thermal Breaks take the form of flat plates of any dimensions, which provide Architects with complete design freedom and Structural Engineers the capability to design to standard codes, with a simple configuration.

Farrat offer three independently tested Structural Thermal Break materials, which are designed to balance high structural performance and low thermal conductivity:

  1. Farrat TBK is most specified across typical connection details, with high compressive strength (312MPa fck) and the best thermal performance in the range (0.187 W/mK).
  2. Farrat TBF is the optimum material when fire performance is a consideration, such as within high-rise buildings, due to its high compressive strength (355MPa fck) and low thermal conductivity (0.2 W/mK) performance characteristics, supported by an A2, s1,d0 Non-Combustible Classification.
  3. Farrat TBL is the favourable material when structural loadings and requirements for thermal performance are lower, and budgets are constrained, offering medium compressive strength (89MPa fck) and thermal conductivity (0.292 W/mK) performance characteristics.

 

 

2. What thickness of thermal break should I specify?

Farrat Structural Thermal Breaks come in a range of thicknesses from 5mm t0 25mm. The only way to accurately calculate the thickness of a structural thermal break is to carry out finite element analysis on the connection and its allied components. This is not common practice due to the relative rarity of details requiring Structural Thermal Breaks and the time and cost of carrying out the thermal modeling.

However, it is possible to understand from a typical example the effects of thickness of plates on example connection.

Farrat illustrates this for their products using BRE (Building Research Establishment) certified thermal models, which show that despite achieving a lower thermal performance than the surrounding building fabric, it is possible to remove the negative effects of a cold bridge with a minimal amount of insulating material (typically a 15mm -25mm thickness). Plates may be used in multiples, but 25mm will mitigate most thermal bridge issues for dwellings and commercial office building details.

3. Do Structural Thermal Breaks need to be as thick as the surrounding wall insulation?

The primary determinate for the thickness of a Structural Thermal Break is its effect in achieving a satisfactory critical internal temperature factor on the warm side of the structural connection. It is not necessary for the Structural Thermal Break thickness to match the surrounding wall insulation thickness to be a success.

Since the thermal break is required to be a structural element, it will always be a relative weak point as an insulant.

However, as illustrated in Farrat’s latest Passive House Certified Details, this still makes it possible to achieve the highest of building performance standards.

4. Will the Structural Thermal Break meet my U value requirements?

U value calculations are the simple method of understanding the thermal performance of a build-up of construction materials in a flat plane (planar). Structural Thermal Breaks are typically used to solve problems in ‘point’ structural connections or in some case linear connections. As such their performance cannot be calculated using the U value method of calculation and require a Psi or Chi value calculations to be undertaken.

These calculations can only be undertaken using 2D or 3D finite Element Analysis (FEA) modelling.

As this is currently not common practice, Farrat utilise their typical BRE Certified Thermal Models, to provide indicative Psi and Chi values for common structural connections to allow simplified specification of structural thermal breaks where calculation models have not been created.

 

 

5. Do Structural Thermal Breaks need to be Non-combustible?

The use of non-combustible materials, particularly in high-rise buildings has become more commonplace in recent years due, in part, to high-profile building fires and subsequent investigations.

Structural Thermal Breaks are extensively used as part of the structural support in façade systems or as the main structural connection in balconies. These elements are key to the performance of the building envelope in the case of fire and the avoidance of catastrophic failure and collapse.

Farrat TBF is an A2,s1,d0 non-combustible Structural Thermal Break material that is capable of withstanding 1000°C heat and maintains its structural integrity in the event of a fire.

Different building types and legislators have differing technical and regulatory requirements for fire design, but if fire is a concern that requires addressing, then the use of non-combustible thermal breaks is one way to mitigate that risk.

Farrat TBF

For more information on integrating thermal break solutions into typical, or bespoke, structural steel connections, visit our Structural Thermal Break hub or one of our dedicated portals:

 

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