Architect: Chapman Taylor
Main contractor: Sir Robert McAlpine
Specialist contractor: Techrete (UK) Ltd
Type of works: supply of Sikaflex PRO 2 HP high-performance joint sealant.

A revolutionary high-performance joint sealant, Sikaflex PRO 2 HP, from Sika has allowed Bristol’s newly built Cabot Circus to retain its striking aesthetics whilst safeguarding it from the weather.

Part of a £500 million regeneration of Bristol’s city centre, Cabot Circus has been designed and masterplanned by award-winning architects Chapman Taylor, who have recently received the Queen’s Award for Enterprise. Comprising a mix of retail, office and residential architecture, with a central glass roof the size of one and a half football pitches, the scheme has been developed by contractor Sir Robert McAlpine. Specialist contractor Techrete (UK) Ltd provided over half of the precast cladding for the project with a mix of natural stone and brick faced pre-cast concrete for a superior aesthetic.

To ensure the buildings’ faces stood the test of time, it was essential the structures received full sealing. Without this, the structures’ joints could fall victim to water and air ingress, which would damage the buildings’ environmental performance. Repair would be costly. Alternative methods of sealing could be detrimental to the overall look of the façades. This was easily solved by Sikaflex PRO 2 HP which is available in a range of colours. They enabled a selection of colours that would blend with the various stone façades used around the project, making it virtually invisible.

Sikaflex PRO 2 HP joint sealant was specified by Techrete. The company holds a long-standing relationship with Sika and the high-performance joint sealant is its product of choice. As part of the service, the companies carry out a programme of testing to ensure the compatability of the Sikaflex PRO 2 HP joint sealant with various cladding panels. Techrete was able to easily apply the versatile, single-part polyurethane façade sealant to all joints around the building, providing all over, effective weatherproofing.

Sikaflex PRO 2 HP's high workability ensured the application process was smooth. Its low modulus and durable finish comes from the use of polyurethane technology, and provides a movement capability of 25% in accordance with ISO 11600 and further tested to +/- 70% in accordance with BS 9047. A high-performance sealant, Sikaflex PRO 2 HP provides specifiers with the reassurance of longevity and cost effectiveness. It is a solution that will keep working for the structure for decades to come, with an impressive long term track record. A small cost to the overall build – a fraction of 1% – it outperforms other inferior grades of sealants, which are prone to failure and result in costly building maintenance. Approved to the highest level of sealant standards, BS EN ISO 11600, Sikaflex PRO 2 HP ensures the project has top-class weatherproofing and airtightness that will not let it down. To ensure correct application each and every time, it is also supported by Sika’s Contractor Training academy.

A reflection of breadth of Sika’s product range, the company provided a number of other materials as part of the scheme. This included over 10,000m² of Sikafloor Car Park Systems, 60,200 litres of Sika Admixtures and 1,000m² of Sarnafil Roofing.

Now completed, Cabot Circus’ thousands of visitors a year can enjoy a striking mix of stone- and brick-faced aesthetics in safe, comfortable conditions all year round.