Terracotta tile claddings on Thames-side development

Scaffolding eliminated from construction sequence
By John Pritchard

Set within 10 acres of landscaped parkland on one of the most sought after stretches of the River Thames between the fashionable neighbourhoods of Chelsea and Fulham, St George plc’s award winning Imperial Wharf development provides a range of two, three and four bedroom apartments and penthouses with spectacular panoramas of the river itself and beyond. Its tree-lined boulevard also offers its residents and visitors a selection of stylish shops, bars and haute-cuisine restaurants to enjoy.

Designed by Broadway Maylan Architects, the Imperial Wharf development is being constructed in a number of phases. Significantly, its major buildings feature is the use of architectural precast concrete with reconstructed stone finished and terracotta tile faced wall panels.

When the current phase of the development is completed shortly, The Marble Mosaic Co Ltd’s run of six precast cladding work packages will have included the casting of more than 6000 units, totalling close to £7m in value. The first phase was completed for Bilfinger Berger Ltd on a supply-and-fix basis in 2005. The next three phases were completed for Carillion Plc during 2005 and 2006 and not only included the detail design, manufacture, delivery and fixing of the wall cladding panels but also the supply of precast concrete balcony units.

The precast cladding panels for the fifth and sixth phases have been and are currently being provided respectively on a “detail design and supply only” basis for J Reddington Ltd and its main contracting division Midgard Ltd.

The majority of the precast cladding panels for each phase are storey-height units that span between the floor slabs, thereby avoiding the need for secondary backing structure for their vertical support or lateral restraint. The other cladding panel types include spandrel units that face the edges of the structural floor slabs and insitu balconies. All the panels were designed to avoid the need for an external scaffold for their safe and efficient installation.

The reconstructed stone finished precast cladding panels are typically 150mm thick and match the appearance of Portland and Bath limestones. Their colours have been achieved without the need for any pigmentation by using special mixes of either Derbyshire limestone aggregate or Cotswold gravel with white cement. Their seen surfaces have been lightly textured using a controlled technique developed by The Marble Mosaic Co Ltd to achieve a notably consistent overall appearance.

The terracotta panels have been cast with red Gima tiles, supplied by NBS in the form of 25mm thick facings cut from standard tiles, and a 150mm concrete backing. All the precast cladding panels have been manufactured with carbon steel reinforcement and fixed using stainless steel fittings.

The joints between the cladding panels have been pointed with a two-stage silicone-based sealant. Incidentally it should also be noted that, with the panels being cast using grade 45 concrete mixes, they provide a robust and durable cladding material that is inherently non-combustible and fire resistant with valuable sound-controlling properties.

If alternatively specified, they could have been supplied with insulation either as an internal core or as a backing to enhance their thermal performance. The required “U” value through the overall wall section has however been achieved using an independent insulated dry-lining system on this occasion.

More information: www.marble-mosaic.co.uk