Rathbone Market is part of the huge Canning Town and Custom House regeneration programme.
A three-phase development delivering a new library, 652 new homes and a new market square, bordered by around 35,000 sq ft of shops, cafes, offices and community facilities.
With two phases already completed by Schock, this final phase will deliver 216 new homes in a mix of one, two and three-bed designs within three blocks. They range in height from 6 to 14 storeys, in a horse-shoe configuration. On the upper levels the majority of apartments will have a double aspect and all will have a generous balcony finished in a powder-coated gold.
The balconies are an unusually demanding 2.3 metre cantilever and to meet the standards required the Schöck Isokorb type KS heat insulating structural load-bearing element has been incorporated. The Isokorb offers a range of technical solutions and all with verifiable performance standards that meet full compliance with the relevant UK building regulations. BBA Certification and LABC Registration. It contains 80mm of insulation and is 180mm wide and between 180 and 280mm high, allowing adjustment for differing slab thicknesses. The units can bear extremely heavy loads, making them an ideal choice in meeting the thermal and structural demands of such large modern cantilever steel balconies.
Chris Willett, Managing Director of Schöck Ltd commented on why working with SIG has helped build closer relationships with the main contractor John Sisk “The project is based on what is a busy and confined site in East London, the SIG branch at Ruislip stocked the Isokorb products, which enabled us to service the project efficiently and effectively with the use of their F.O.R.S. accredited vehicles”.
Vaughan Taylor, National Sales Director for Construction Accessories & Builders Merchants said of Schock: “The dedication and expertise shown by both the SIG CA team and Schöck to this project has ensured this third phase of the project met the demands of the Contractor, by working together we have consistently delivered a high quality service throughout”.
A particular technical challenge offered by Rathbone Market is that such large free cantilevered steel balconies can be prone to vibration when there is heavy movement on them. As vibration is considered to be a serviceability issue, the perception of discomfort varies from one individual to another, so what constitutes acceptable vibration is not straightforward.
A sensible approach is to design structures so that their natural frequency is sufficiently beyond potential excitation frequencies and to assess how prone to vibration such thermally separated balconies might be, the latest Natural Frequency Calculator software package was employed.
This is a free service from Schöck which uses geometric and material variables. When applied on this project it was found that the Natural Frequency of the balcony constructions was comfortably above the recommended limit. In general, depending on the type and utilisation of the structure, published data indicates limit frequencies of between 4 Hz and 7.5 Hz. Experience has shown that adopting a limit frequency of 7.5 Hz for steel balconies not only eliminates the possibility of undesirable vibration, it also enables cost-efficient design.