Minimising energy use in buildings by improving building envelope thermal performance is increasingly important in the drive for sustainability and energy efficiency. And the prevention of thermal bridging is critical with structural attachments such as balconies. Ineffectual insulation at the connection points means local heat loss, resulting in more energy being required to maintain the internal building temperature. And there are other issues. Low internal surface temperatures in the area of the thermal bridge can cause condensation, leading not only to structural integrity problems with absorbent materials such as insulation products or plasterboard – but also the potentially serious occurrence of mould growth. So for any large-scale project involving different balcony types, the prevention of thermal bridging is critical.
Challenging variety of balcony types
One current project with a challenging variety of balconies is Hendon Waterside in North West London, a mixed tenure housing development. Situated alongside the Brent Reservoir, (known locally as the Welsh Harp, after a public house which used to stand nearby), the scheme involves the regeneration of a 1960s housing estate being built in six phases and scheduled for completion in 2027. The masterplan will deliver around 2100 new homes consisting of social, affordable and private housing. These are being constructed in twenty-three blocks, varying in height from three to twenty-three storeys – along with an imposing tower building of twenty-eight storeys. Also planned are new public parks, a primary school, community centre and space for small cafes or shops.
Hundreds of Isokorb variants in the range
The construction of the many balconies involved vary in their design demands and to ensure the risk of thermal bridging is minimised, Schöck has supplied over thirteen different product variants. As the leading international supplier of structural thermal breaks, Schöck can provide a solution to practically every connectivity detail with the hundreds of variants available in its main Isokorb range; offering planners enormous design freedom. The products used here are for concrete-to-concrete and provide optimum solutions through the use of varying tension bar arrangements. For example one type provides cantilever balcony connections and transfers both negative moments and positive shear forces. Another is a load-bearing thermal break element for transferring shear forces on supported balconies, recessed balconies and for occasional peak shear forces. Others transfer positive shear forces with point support, or transfer positive shear forces with point support and zero stress connection.
Totally verifiable performance
In addition to concrete-to-concrete, the comprehensive Isokorb range also offers solutions for concrete-to-steel and steel-to-steel – and even a maintenance free alternative to wrapped parapets. A requirement 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 Isokorb. The range also complies with SAP 2012, concerning CO2 emissions from buildings and heat losses through non-repeating thermal bridges. Products meet full compliance with the relevant UK building regulations, have NHBC approval and offer LABC Registration. There is also the security of independent BBA Certification.
For a free copy of the Schöck Thermal Bridging Guide; the Schöck Specifiers Guide or to view the range of downloadable software, contact Schöck on 01865 290 890 or visit the website at www.schoeck.co.uk