Tag Archives: thermal bridging

Latest Schöck BBA Certification raises the bar

Schöck Isokorb BBA Certification

The latest BBA Certification awarded to the Schöck Isokorb is the culmination of an unprecedented standard of assessment by the BBA.   It has resulted in a much more demanding new generation of Agrément Certificates for thermal break products and the emergence of a new ‘Leader Certificate’.   This new ‘Leader Certificate’ incorporates significantly more detailed content on structural stability and performance of the balcony connector.

The rigorous assessment by the BBA involved tests for structural stability, fatigue stresses and fire. As a result, the enhanced Certificate includes a full description and specification of each component. Specification of threaded steel bars to connect the system to steel balcony; limitation for deflection of the concrete slab and steel; the requirement for fatigue stresses due to different temperatures and for natural frequency of the external concrete slab and steel balconies; thermal bridging at the junction between the balcony and the wall. In addition, it covers behaviour in relation to fire.

The BBA’s Project Manager, Seyed Tajallifar, emphasises that: “All future Agrément Certificates of this sort will follow this format. The items covered in the Schöck Certificate will be included in any other balcony connector Certificate when they are due for Reissue.”

Chris Willett, MD at Schöck comments: “We have always welcomed our collaboration with the BBA, which dates back over several years. This new generation BBA Agrément Certificate takes a huge step in providing the highest level of assurance to the construction industry and we are certain that it will lead to further specifications of our product in the future”.

For a free copy of the Schöck Thermal Bridging Guide and / or the Thermal Bridging Solutions brochure – contact the company on 01865 290 890 or visit www.schoeck.co.uk

 

HOOLA precast balconies a team effort from Schöck and Thorp

the HOOLA

Tidal Basin Road in East London, gateway to the soon-to-be regenerated Royal Victoria Docks area and a short stroll from the Excel Exhibition Centre, is now home to a new twin tower glass-clad landmark building – the ‘HOOLA’.

This £80m development has transformed a brownfield site into two rippling 23 and 24 storey glass towers that effectively sit on a ‘landscaped lid’; which covers the single level basement and accommodates parking and refuse plant spaces.

The buildings are super-insulated and the concrete frame will act as a heat sink – absorbing heat on warm days and releasing it back into apartments when it cools.

An innovative link-up with the neighbouring ExCel Exhibition Centre will also see excess heat piped directly into the two towers.

the HOOLA

There are 360 apartments with a mix of studios, along with one, two and three-bedroom units.  All apartments have floor-to-ceiling windows and sliding doors with balcony access, so a critical design requirement for such a super-insulated building was the avoidance of any risk of thermal bridging at the many concrete-to-concrete balcony connectivity points.

Highly efficient structural thermal breaks were therefore required throughout and the preferred solution was the Schöck Isokorb type K for cantilever balconies.

With its innovative HTE pressure-bearing module and Neopor® core, the unit provides extremely high thermal resistance; and is also a load-bearing element which transfers bending moment, stress and shear forces.

Complex balcony detailing for Thorp Precast

The balconies on the HOOLA, which are all precast in a Reconstituted Portland Stone Concrete, meant that thermal break suppliers Schöck had to work closely with specialists Thorp Precast of Newcastle-under-Lyme.

Luke Smerdon-White, Technical Director at Thorp, takes up the story:

“We had to design, manufacture and deliver 1410 precast concrete balcony sections that had to then be cast integrally with the in situ concrete structure.

The design and detailing coordination on our part was taken from the 2D consultant’s information, which we converted into 3D Tekla modelling.

The balcony detailing is complex. The exposed front-face is curved, with almost 50 different dimensional configurations, while the internal face has a facetted line that had to correlate with the glazing line and opening doors.

The ability to integrate the Schöck Isokorb thermal breaks using 3D BIM details was critical; as we had to both accommodate the slab and column reinforcement – and achieve the finite positioning of the connection modules for structural and cost efficiency”.

the HOOLA

On super insulated buildings, balcony insulation is especially critical

Research at the Oxford Institute for Sustainable Development (OISD) at Oxford Brookes University shows that as a result of airtightness and fabric U-values being improved in UK building, thermal bridge heat losses are responsible for an increasing percentage of the overall building heat loss.

It is common for thermal bridges to account for 20% – 30% heat loss in multi-residential units (as calculated by thermal modelling) and balcony connections can be a major contributor to the thermal bridge heat loss if effective thermal isolation is not included in the design.

Schöck offers a number of highly effective solutions to various thermal bridging situations.   In addition to concrete-to-concrete capability, the Isokorb range provides totally verifiable solutions for concrete-to-steel, steel-to-steel and even a maintenance free alternative to wrapped parapets.

All solutions meet full compliance with the relevant UK building regulations and offer BBA Certification and LABC Registration. The requirement that the temperature factor used to indicate condensation risk (the fRsi value), in residential buildings, must be equal to or greater than 0.75 is comfortably met by incorporating the Isokorb.

For a free copy of the Schöck Thermal Bridging Guide and / or the Thermal Bridging Solutions brochure – contact the company on 01865 290 890 or visit www.schoeck.co.uk

Comprehensive Schöck range meets Embassy Gardens demands

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Stretching along the south bank of the Thames from Battersea to Vauxhall, the Nine Elms area in London, for so long a neglected stretch of industrial land, has become the largest development zone in Central London.   Over the next ten it will see 20,000 homes built, along with new schools, parks, cultural centres, a pedestrian and cycle bridge over the Thames; and the opening of two new London Transport underground stations.

The residential and commercial heart of this huge development is Embassy Gardens, London’s new diplomatic precinct on the riverside.  It forms the backdrop to the new US Embassy, scheduled to relocate from Grosvenor Square during 2017.  The blocks are arranged around raised courtyards, with retail and commercial frontages at ground level that connect the Embassy Square, Linear Park and River Frontage through a network of streets and a central square.

There are differing building heights to minimise overshadowing and overlook and the buildings incorporate a wide array of public and amenity spaces including communal courtyards, roof gardens, private terraces and balconies.

 Schock

The first release of apartments in Embassy Gardens is the Ambassador Building, which comprises six distinct cores, which house not only the residential apartments, but also a fully equipped private members club to rival the best in any international hotel.

The development has inevitably attracted a sophisticated level of residents who demand the highest standards of detail throughout these buildings; and one of the key features is the wide variety of balcony types, each governed by unit size and orientation.

OISD confirms need to minimise thermal bridging

With such a demanding specification involving different balcony types, the minimisation of any possible thermal bridging problems is crucial. This is something highlighted in research findings from the Oxford Institute for Sustainable Development (OISD) at Oxford Brookes University.

It shows that with increasingly improved airtightness and fabric U-values in UK buildings, thermal bridge heat losses are responsible for an increasing percentage of the overall building heat loss.   It is common for thermal bridges to account for 20% – 30% of the heat loss in multi-residential units (as calculated by thermal modelling) and balcony connections can be a major contributor to the thermal bridge heat loss – if effective thermal isolation is not included in the design.    And the company able to offer the ideal range of solutions to the differing thermal connectivity demands posed by the complex balcony designs at the Ambassador Building is Schöck.

Isokorb type KS for concrete-to-steel

Verifiable performance standards and full compliance

The diverse range of Schöck Isokorb load-bearing thermal insulation products guarantees totally verifiable performance standards, meets full compliance with the relevant UK building regulations and offers BBA Certification and LABC Registration.   The specific requirements at the Ambassador Building involved firstly the Schöck Isokorb type K for concrete-to–concrete connectivity.

The type K units were incorporated into the cast in-situ cantilever balconies on the road facing external elevation; and where there was a shear force transfer element required, also involving concrete-to-concrete loggia’s or supported balconies, the Isokorb type Q was installed.  A further variation, Isokorb type K-WU units were also used as slab-to-wall thermal breaks.

Isokorb type KS for concrete-to-steel

The Isokorb type KS for concrete-to-steel were used on the internal courtyard balconies; and to assist the structural engineer in keeping the transverse beam continuous between the external columns, Schöck SLD dowels were also used to support the propped cantilever walkway externally.

In addition to providing highly effective connectivity solutions for concrete-to-concrete and concrete-to-steel thermal bridging situations, the Schöck Isokorb range also offers a modular product for steel-to-steel applications and even a maintenance free alternative to wrapped parapets.

When any Isokorb product type is incorporated into residential buildings, the required fRsi value – the temperature factor used to indicate condensation risk that must be equal to or greater than 0.75 – is always comfortably met.

For a free copy of the Schöck Thermal Bridging Guide and / or the Thermal Bridging Solutions brochure – contact the company on 01865 290 890 or visit www.schoeck.co.uk

Continuous ribbon balconies require effective thermal insulation

 SCHOCK

The Chiswick Point development, at Bollo Lane, in West London, is a £20m contemporary mixed-use residential scheme offering 124 one, two and three bedroom residential apartments, including three penthouses.  The apartments are either south facing single aspect, or dual aspect with some even enjoying a triple aspect.    A sustainable approach was important, with all of the units designed to meet Level 4 of the Code for Sustainable Homes, and the Lifetime Homes code.   Constructed in two blocks of six and nine storeys, the frame is mainly reinforced concrete, with the concrete frame floors and cladding providing thermal mass, which absorbs energy and slowly releases it to help reduce temperature fluctuations.

Long continuous ribbon balconies provide solar shading to the two blocks and provide the residents with a very pleasant outlook across the London Wildlife Trust nature reserve at the rear of the development.     The continuous balconies are a major feature of the scheme and with several hundred metres of them winding across the two blocks, effective thermal insulation was imperative if thermal bridging is to be avoided.   To minimise any condensation problems and subsequent mould growth as a result, plus the avoidance of thermal outflow, Schöck Isokorb type K heat-insulating load-bearing elements are installed at various strategic positions along the large expanse of balconies.   The Isokorb type K provides high thermal resistance by using stainless steel bars to act as tension and shear reinforcement, plus high-strength HTE pressure bearing modules.

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Research at the Oxford Institute for Sustainable Development (OISD) at Oxford Brookes University shows that as a result of airtightness and fabric U-values being improved in UK building, thermal bridge heat losses are responsible for an increasing percentage of the overall building heat loss.   It is common for thermal bridges to account for 20% – 30% heat loss in multi-residential units (as calculated by thermal modelling) and balcony connections can be a major contributor to the thermal bridge heat loss if effective thermal isolation is not included in the design.

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Schöck offers a number of highly effective solutions to various thermal bridging situations.   In addition to concrete-to-concrete capability, the Isokorb range provides totally verifiable solutions for concrete-to-steel, steel-to-steel and even a maintenance free alternative to wrapped parapets.  All solutions meet full compliance with the relevant UK building regulations and offer BBA Certification and LABC Registration. The requirement that the temperature factor used to indicate condensation risk (the fRsi value), in residential buildings, must be equal to or greater than 0.75 is comfortably met by incorporating the Isokorb.   It also complies with the Government Standard Assessment Procedure, SAP 2012, concerning CO2 emissions from buildings and respectively heat losses through non-repeating thermal bridges. The lambda values of the Isokorb enable energy loss to be reduced by as much as 84% to 91% in various connective situations.

For a free copy of the Schöck Thermal Bridging Guide and / or the Schöck Specifiers Guide – contact the company on 01865 290 890 or visit www.schoeck.co.uk

 

Schöck solution combines architecture with horticulture

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Huge medicinal herbs on the façade of the Berlin medical centre

The striking façade of this building in Berlin is the concept of Sergej Dott, a locally-based pop art painter who chose medicinal herbs to represent the building’s use as a major medical centre.   The Treptow Medical Centre, named after the district in which it is located, is a 19th century listed building and recent refurbishment work has seen the interior transformed into twelve surgeries and a pharmacy.  The final flourish of the restoration activity is the addition of the pop art herbs, each one metre in diameter, up to twelve metres high and 600kgs in weight, all grouped around three sides of the building.

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The KST makes it possible to secure the flowers directly to the medical centre’s steel structure

To incorporate them into the structural design, additional steel beams had to be installed inside the building at varying floor levels and Lorenz Linnhoff, whose engineering firm carried out the structural planning for the building comments: “The optimum solution for fastening the giant flowers to the building envelope was the Isokorb KST, which made it possible to transfer the load of the flower installation via the steel beams to the load-bearing building”.

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The KST load-bearing thermal insulation element Is used to fasten free cantilevered steel beams to steel structures

The KST has been developed to create thermal breaks in steel structures, where the modules are used to transfer tensile forces and pressure/shear forces.  With this application the product is used only for the latter purpose, as on this occasion it has to perform a structural function rather than ensure thermal partition.     Each flower is connected by two KST modules at the top of the stalk and their modular capability meant that off-site pre-fabrication was possible, helping to reduce on-site costs.  Two head plates were welded to the stalks off site and another two head plates attached to the main steel structure with the KST modules bolted to them.  Then flower stalk was then lifted into position and the two plates simply bolted to the exterior connections of the KST units.   The community arts and culture scene in Treptow wil benefit too, as each of the herbs is to be sponsored, with the proceeds donated to various art institutions.

For your free copy of the new Schöck ‘Thermal Bridging Guide’ and / or the comprehensive 236 page ‘Technical Guide’ contact the company on: 01865 290 890 go to http://www.schoeck.co.uk; or email: design@schoeck.co.uk

http://www.schoeck.co.uk

Riverwalk incorporates high specification Schöck Isokorb

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London’s three historic embankments – Chelsea, Victoria and Albert – are currently being transformed as part of a regeneration scheme that will replace many of the outdated buildings which have characterised these areas for so long.  The result will see the development of new homes, promenades and parks – and one of these commanding new developments, on the north bank of the Thames, is the stunning Riverwalk, at Millbank, designed by Stanton Williams.

Riverwalk features two organically shaped buildings of 7 and 17 storeys, connected by a central podium and incorporating 116 high specification one, two, three and four bedroom apartments, plus penthouses. The design focus is on light, space and service, as well as exceptional views across the River Thames.   Extensive planting on roofs, balconies and terraces, most significantly on the first floor podium terrace, also contribute to a substantial improvement in the green footprint and biodiversity of the site.

Aesthetically the buildings are enhanced further by horizontal bands of limestone on the curving facades between the glazing and ceramic panels, with the stonework wrapping around the lower parts of the balconies to create a continuous organic shape. The balconies vary in depth and this in turn provides the outer façade with a sense of depth, along with natural solar shading.

With such a high specification development it is not surprising to find that enormous consideration was given to the avoidance of the thermal bridging at the critical balcony connections; and the structural thermal break module specified throughout is the latest generation Isokorb type KXT from market leaders Schöck.

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The type KXT – for concrete-to-concrete applications – offers such a high level of insulation that the Passivhaus Institute in Darmstadt has awarded the product with the “low thermal bridge construction” certificate and confirmed its suitability even for passivhaus construction.

A major reason for the superior performance of the Isokorb type KXT is the thickness of the insulation body. This is  increased from the standard 80mm thick to 120mm, providing an even more efficient solution. The KXT not only improves thermal insulation performance by up to 30% in comparison to to the standard range, it also improves impact sound insulation by around 50% as well.  High quality stainless steel bars with improved tensile strength is an integral part of the unit and while the same load-bearing capacity is maintained, there is a smaller rod diameter and therefore a reduction in the thermally conducting cross-section, resulting in a further increase in the heat insulation performance.

A further reason for the superior performance of the Isokorb type KXT is the HTE module, a pressure bearing block made of steel fibre reinforced high-performance concrete with Kronolith, a titanium ore aggregate from Kronos Titan.  The unit offers architects and engineers a variety of design options and there is even the capability to construct stepped height balconies, with increased fire protection also taken into account, as the HTE module offers fire-resistance class F 120.

Schöck, is a specialist in the provision of advanced solutions for thermal energy structural insulation and best known for its range of structural thermal break units.  It is a range which allows connections to be made between concrete-to-concrete, concrete-to-steel and steel-to-steel and all units meet full compliance with the relevant building regulations, while also providing BBA Certification and LABC Registration.   The requirement described in BRE IP1/06 – a document cited in Building Regulations Approved Documents Part L1 and L2 and Section 6 in Scotland – states that the temperature factor used to indicate condensation risk (fRSI) must be greater than, or equal to, 0.75 for residential buildings and this is easily met by incorporating the Isokorb.

In addition, there is also compliance with the Government Standard Assessment Procedure, SAP 2012, concerning CO2 emissions from buildings and respectively heat losses through non-repeating thermal bridges.  Here, the lambda values of the Schöck Isokorb enable energy loss in various connective situations to be reduced by as much as 84% to 91%.

For your free copy of the Schöck Specifiers Guide and / or the new Thermal Bridging Guide – contact the company on 01865 290 890 or visit www.schoeck.co.uk

Unusual high load cantilever walkway challenge

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The Kidwells Estate, a 1960s-built initiative just outside Maidenhead town centre, in Berkshire, is undergoing major regeneration which involves the construction of  seven new blocks. These vary from three to six storeys of structural concrete frame and are part timber clad.  Long cantilever walkways that service multiple flats on the complex form an unusual feature of the new development and the demands of the walkways presented a technical challenge for the structural thermal breaks used in their construction.  

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Now known as Parklands, the former Kidwells Estate, is a landmark £27.1 million project, scheduled for completion later this year. It is a scheme for One Housing and in replacing seven 1960s-built apartment blocks, the redevelopment will provide 204 new mixed tenure high quality homes, consisiting of 75 homes for rent to existing and new tenants, nine shared ownership homes and 120 homes for private sale.  On completion the development will provide three and four bedroom family homes; as well as one and two bedroom apartments.   One Housing manages over 15,000 homes across 27 London boroughs and surrounding counties; and in the last three years has delivered more than 1,500 new affordable homes, with plans to build a further 3,600 by 2019 to help meet the housing shortage.

The unusual construction challenge involving the walkways at Parklands, is brought about because the design consideration, both aestheticaly and for the benefit of residents and visitors, requires as much natural light as possible to be available in the areas around the cantilever walkways.

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To meet this requirement, extensive light wells have been introduced at regular intervals along the length of the galleries.   These wells are effectively a series of elongated spaces, which separate the walkways from the building for large sections.   As a result, there are far fewer structural connection points between the walkways and the building than would normally be anticipated, so the connectivity opportunities are very limited. The walkways themselves being cantilever concrete construction into internal reinforced concrete frame.

Schöck is the supplier of the structural thermal breaks and because of the restricted connectivity point opportunities, the products had to resist a much greater shear load than would be the case with a more conventional design.   In addition to this, the support condition of the external columns and edge beams also had to be taken into account and there was a limitation too on slab thickness for the dowel connections.

The solution required a relatively unusual combination of products and the issues were resolved by Schöck designing in its type HPC Isokorb.  It is a product utilised only if horizontal, tension and compression forces are present in the design and additionally it is necessary to integrate the type QP90+QP90 Isokorb as well, for linear or point connection to support high shear loads.   Schöck type SLD Q50 heavy duty stainless steel dowels were also incorporated to enable the transfer of vertical shear forces and allow two directional lateral movements at the expansion joints.   The result was a completely secure thermally insulated load-bearing connection at all of the restricted, but key structural points.

HPC Isokorb
HPC Isokorb
QP10
QP10

The Isokorb structural thermal break range enables connections to be made between concrete-to-concrete, concrete-to-steel and steel-to-steel – and the many different unit types available, combined with their ability to enable the transmission of shear, bending moment, tension and compression forces, also means that the options available effectively run into hundreds when the different combinations are taken into account.

All units provide BBA Certification and LABC Registration and meet full compliance with the relevant UK building regulations.

The requirement described in BRE IP1/06 – a document cited in Building Regulations Approved Documents Part L1 and L2 and Section 6 in Scotland – that the temperature factor used to indicate condensation risk (fRSI) must be greater than, or equal to, 0.75 for residential buildings, is easily met by incorporating the Schöck Isokorb.

A comprehensive 236 page ‘Technical Guide’ is available, which displays in detail the complete range of thermal break applications for all construction types – concrete-to-concrete, concrete-to-steel, steel-to-steel and concrete-to-timber.

A new free ‘Thermal Bridging Guide’ is also available on request

Contact Schöck on 01865 290 890 go to www.schoeck.co.uk or email: design@schoeck.co.uk