St. Paul’s Cathedral, one of the most cherished buildings in the country, is approaching the 300th anniversary of its completion and, in preparation for its next three hundred years, it has embarked upon a £40 million restoration campaign, which will see the interior and exterior of St. Paul’s repaired and cleaned.

With the restoration of such an historic building, there were various technical challenges to consider. Renowned for their high performance tile fixing products and expert technical support, ARDEX UK were able to provide Trevor Caley Associates Ltd of Northamptonshire with an advanced system solution for the restoration of the Whispering Gallery, within St. Paul’s Cathedral.

Following a site visit to St. Paul’s Cathedral with the architects, Martin Stancliffe Architects and Trevor Caley Associates Ltd, ARDEX recommended a range of products specifically designed to meet the rigorous demands of the project.

The project required one of the existing glass mosaic pendentives to be removed and subsequently reinstated. Following the removal of the mosaics, the exposed background required smoothing with a render to accommodate the varying thickness requirements whilst providing rapid setting and hardening properties. For this purpose, ARDEX AM 100 one coat tiling render was specified as it can be applied from 2-20mm in a single application. Another advantage, unique to ARDEX AM 100, is that the mosaics could be reinstated only 2 hours after the render had been applied. Had a traditional cement-based render been used, a curing period followed by at least 2 weeks drying time would have been required before tiling could commence. The mosaic below the Whispering Gallery forms a curved surface and the reinstatement incorporated a stainless steel 95F mesh reinforcement, which allowed the ARDEX AM 100 to be mechanically secured to the backings.

ARDEX X 7 W white cementitious tile adhesive, incorporating ARDEX E 90 admix, was selected to fix the reconditioned glass mosaics. The combination of ARDEX X 7 W and ARDEX E 90 has been highly effective for this type of installation since the system was introduced in 1982.

The mosaic tiles were then grouted using ARDEX C 2 white cement-based tile grout, incorporating ARDEX E 101 grout admixture. ARDEX C 2 is developed to be suitable for a range of applications from tiles with wide joints down to the narrow joints associated with mosaics. ARDEX C 2 is easy to apply and clean off, helping to provide a perfect finish to this important restoration project.

‘The combination of proven product performance and outstanding technical support provided by ARDEX was a pivotal factor in the completion of our restoration work on behalf of St. Paul’s Cathedral. We would recommend working with ARDEX every time’, enthused Gary Bricknell of Trevor Caley Associates Ltd.

For further information on the ARDEX product range please telephone 01440 714939, Email or visit ARDEX online at

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