The Canaletto residential tower at 257 City Road in London is 31-storeys with 190 luxury one, two and three bedroom apartments built to the standards of Code 4 Sustainable Homes Level 4. The tower is concrete frame and has a curving facade of metal and glass that breaks the volume into a series of three-to-four storey clusters, each containing grouped balcony terraces. The balconies are steel construction connected to the concrete frame and as always with cantilever construction elements, one of the early design considerations was the prevention of thermal bridging.
Thermal bridge heat losses are responsible for an increasing percentage of overall building heat loss, due to airtightness and fabric U-values being improved in UK Building Regulations. Thermal modelling calculations show that for multi-residential projects such as large apartment blocks, thermal bridges could account for 20%-30% of thermal losses, with balcony connections being a major contributor if effective thermal isolation is not incorporated.(1)
The Isokorb range of thermal break elements from Schöck is designed to combat thermal bridging and for the high specification Canaletto project the Isokorb type KS20 offers the ideal solution. This concrete-to-steel connectivity module sits between the outer and inner structural connection points and blocks the outflow of heat through the use of high quality polystyrene insulation foam. There are tension and shear stainless steel bars passing through it, which take the forces between the building frame and the balconies, enabling a thermally insulated, load bearing connection to be made.
The Isokorb range provides a huge selection of solutions for concrete-to-concrete and steel-to-steel, as well as concrete-to-steel – and the entire range offers the security of BBA Certification and LABC Registration. It also comfortably exceeds the requirements of BRE IP1/06 and Part L of the Building Regulations where the temperature factor used to indicate condensation and mould growth risk (fRSI) must be greater than, or equal to, 0.75 for residential buildings.
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