Specifier Review

Schöck makes thermally efficient balcony retro-fit a reality

The debate over the environmental, sociological and financial pros and cons of demolishing or renovating older housing stock will undoubtedly continue. However, increasingly it appears renovation and refurbishment will remain the most significant contributors to progress in terms of energy efficiency and environmental preference. Ever increasing energy prices, more and more stringent building regulations, and many other fast-changing forms of compliance, mean that the traditional pattern of refurbishing a building every forty to fifty years is outmoded.  As a result, if anything close to ‘future-proofing’ is to be achieved, conventional renovation or refurbishment will not be enough – we must look towards ‘thermal renovation’.Image

There is now a huge variety of thermally efficient insulation solutions for old building renovation, and the overall effect of modern exterior insulation technologies, along with the appropriate render, can improve the character of even the most unremarkable of buildings. Add to this superior fenestration technology; floor and roofing insulation; plus the numerous modern technologies for cavity fill.   Until recently, buildings which have to be insulated from the inside – possibly listed, or where facades are an aesthetic feature – have used a substantial thickness of insulation to achieve effective thermal performance.  As a result, the usable interior space was eroded. Now, with the development of significantly thinner insulating materials, this has changed beneficially for the building occupants.    These and many other contributing products and technologies, have resulted in extremely thermally efficient buildings – to the point in many cases where they are practically sealed.

With many of these renovated and refurbished buildings, the retro-fitting of balconies, or the replacement of old thermally inefficient balconies, is in demand.   Balconies aesthetically transform living space and exterior appearance, offer a practical benefit, and are an anticipated add-on for contemporary living accommodation, especially in city centres.   The value of the property is immediately enhanced, and return on investment improved.  However, thermally renovating a building without giving due consideration to the risk of thermal bridging at balcony connectivity points, is almost certainly going to create a serious problem – even if one didn’t exist before.

Low surface temperatures at the thermal bridges, combined with the relatively high air humidity resulting from the newly sealed building envelope, will result in condensation.   This in turn can lead to structural integrity problems with absorbent materials.  Worse still, it encourages mould growth, which has serious implications for building occupants and may cause them to develop certain medical conditions such as respiratory problems and dermatitis.

Two energy efficient solutions for balcony renovation and refurbishment are available from Schöck Ltd – the existing type KST and the new type R.      Although the type KST thermal break unit is designed for steel-to-steel applications, its modular design means the unit can be adapted to become an ’enabling’ thermal connection. The principal being that internally, steel elements are constructed in situ, allowing a steel connection to be built into a wall, or for a frame to be built between the existing floor joists. These respectively allow for supported and freely cantilevered balconies, with the KST module being mounted as the load-bearing thermal insulation element.

The latest development though is the new Schöck type R Isokorb®, which offers an extension to the existing range of KST solutions.  It works with existing reinforced concrete floor slabs, and the installation principle is that drill holes are marked with a template in position on the face of the building. The holes are drilled into the concrete slab, adhesive injected and the type R load-bearing reinforcing rods slipped into position and anchored by means of the pre-injected adhesive. Structural screed is then poured into a special pocket between the product and the concrete slab to ensure a perfect contact between the two structural elements. Once both the mortar and the screed are cured, the structure is ready for the new balcony to be connected.   ImageImage

Residents can remain in the building during external renovation and there is no damage to internal finishes and decoration.  Unlike new-build, product selection for renovation is subject to certain restrictions, and the solution will very much depend on the specific project requirements, the existing building and its structure, as well as the development of customised­ design proposals.

This new product is in response to the increasingly stringent energy performance standards affecting the German and European renovation market. It is estimated that currently around 85% of existing buildings have little or no insulation; but the 2012 German Energy Conservation Regulations, and future regulations, will require buildings to perform to “zero emission” standards at some point between 2020 and 2050.     There is evidence from several CO2 reduction programmes since 1996, that by upgrading, an 80% cut in energy use has already been achieved, making the performance of the renovated homes at least as good as Germany’s demanding new build standards.    In the UK, the argument is that existing stock upgrade is vital, because despite an ambitious new build programme, around 70% of all the homes that will exist in forty years time, have been built already.

Schöck has a comprehensive Specifiers Guide and / or Technical Guide available. For your free copy, contact the company on 01865 290 890 or visit www.schoeck.co.uk

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