One of the tallest new buildings recently added to the Bournemouth skyline has been completed with a combination of external wall insulation and render products supplied by Sto. The company’s StoTherm Mineral M system, with Sto-Rotofix Plus mechanical fixings and StoSilco exterior render were all used on the new Skyline student accommodation building, which achieved a BREEAM ’Very Good’ rating.
The major 17-storey, 430-bedroom project by Gilltown, which was acquired on completion by a major investment company, delivers a combination of purpose-built accommodation and recreation facilities for its residents.
Intersect Architects Limited, who have completed a number of student schemes throughout the country said, “We were looking to specify materials that met our strict requirements in terms of thermal and fire performance, but we also wanted to use materials which reflected the development’s coastal location. The Sto materials gave us the fire-rating compliance and u-value we required. Sto were also able to provide the external render in both a textured stone colour and a smooth, dark grey. When combined with different finishes used on other parts of the building, these perfectly matched the vision which we had for the completed development.”
StoTherm Mineral is a highly durable external wall insulation system which uses mineral-fibre boards that provide outstanding thermal performance and unrivalled fire protection. The dense nature of the materials involved also provided a considerable degree of sound insulation for this student accommodation building, while the efficient single-leaf construction and external location of the system allowed internal space to be maximized.
For this project the Sto insulation was installed by Façade Concepts, who used Sto’s unique Sto-Rotofix Plus spiral fixings. Compatible with many different types of substrates – including the concrete frame construction used on this project – the Sto-Rotofix Plus combines the ease-of-use of ETICS anchors with the ease of adjustment as per a rainscreen cladding system, and reduces the installation times compared to an ordinary mechanically-fixed system. The helical profile of the Sto-Rotofix Plus fixings enables the boards to be installed securely, and also allows them to be adjusted after installation to ensure that a smooth, flat surface is created, ready for finishing layers to be added to the external surfaces of the insulation.
After a Sto cement-free reinforcement layer had been applied, the insulation system was completed with the application of the company’s StoSilco silicone resin render. This provides the finished surfaces with a highly water-repellent surface that is ideal for buildings such as this where a coastal location may subject them to unusually harsh weather conditions. With excellent CO2 and water-vapour permeability this render allows moisture transfer to occur at a high rate, enabling the wall to breathe and encouraging the evaporation process. The StoSilco render is available in an extended range of 764 colours from the StoColor System, and this provided extra benefits for this particular project.
It allowed the architects to specify exactly the colours they needed to create a series of visually-contrasting elements. A dark grey RAL 7016 colour was used for the render between the windows and across the top two floors, and this was then overcoated with StoColor X-Black façade paint. This paint uses special black pigments which reflect much of the solar energy in the invisible near-infrared spectrum, and allows for a relatively cool surface, although the render surface is a dark colour. This protects both the render itself, and the insulation it covers, from the damaging extremes of thermal stress. A contrasting RAL 31437 cream colour was used in other areas, giving the overall development a strong character, but crucially, without compromising the practical performance of the building in any way.