When it came to specification of the roofing system, specialist contractor Metclad recommended a single ply membrane from Sika-Trocal.
Working with structural engineers Heyne Tillett Steel, Lifschutz Davidson Sandilands designed the six-bed, single storey hospital extension to be a visually stunning metallic linear pod. For the roofing system, durability and whole life costs were of utmost importance as well as a simple installation process, helping to ensure the new ward could be constructed efficiently to minimise disruption to the hospital.
Although the original design incorporated a felt roof, following consultation between the architects and roofing contractors, Metclad specified Sika-Trocal single ply system for its fast, efficient installation process.
Sika-Trocal supplied 500m2 of its cold applied Type S roofing membrane. Using the Sika-Trocal single fix fastening system, Metclad mechanically fastened a series of flat laminated metal discs to the roof, penetrating through the roofs insulation, directly into the structure. Once the discs were installed, the roofing membrane was simply unrolled over the substrate and chemicallywelded – using Sika Trocal’s THF Welding Agent – with each membrane roll carefully overlapped to provide a completely watertight roof.
The installation system provides an effective method of mechanically fixing the membrane at the same time as the insulation. This single fix approach reduces the number of fixings required whilst speeding up installation and in turn reducing costs.
With the site of the new Teenage Cancer Trust Ward oversailing two fully functional departments – the hospital’s main A & E entrance and a minor fractures unit – both of which were to remain in operation throughout construction, the Sika-Trocal Disc System proved a quick method of installing the new roof, helping to keep the fast track construction programme on schedule.
“We have used Sika-Trocal on a large number of projects and it remains one of our favoured flat roof systems,” commented Roger Whitehead, Director at Metclad. “Its fixing system offers a labour efficient and cost effective way of installing a new roof, whilst the membrane itself offers long term performance.”
To eliminate thermal bridging, often caused via roof fixings, Metclad specified thermally broken fasteners that incorporate plastic sleeves that form a barrier between the screw and the building fabric. This combined with the impressive air tightness credentials of Sika-Trocal has ensured that the completed roof aids the creation of a thermally efficient building envelope.
With this in mind, the building gained a nomination for the David Alsop Sustainability Award at the Structural Awards 2010 thanks to the performance of the Sika-Trocal membrane plus a host of other sustainable elements, including the use of wood surfaces in place of traditional metal or plastic where possible and LED proximity-sensor lighting in corridors and bathrooms.
Offering exceptional waterproofing, durability and a simple installation process, Sika-Trocal, which is approved by the British Board of Agrément (BBA) to have a life expectancy of up to 30 years, has ensured that the Teenage Cancer Trust Ward will provide a positive, welcoming environment for many years to come.
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