It’s no secret! IKO and Sussex Asphalte restore whispering gallery

IKO PLC and Sussex Asphalte recently won a UK Roofing Award for Best Mastic Asphalt Project, for their work on the Stone Gallery in St Paul’s Cathedral. The ceremony took place at the Park Plaza hotel in Westminster Bridge in May.

The awards, organised and hosted by the National Federation of Roofing Contractors (NFRC), celebrate outstanding standards of design workmanship and safety in the industry, and the work on the Stone Gallery was a prime example. It is the first of two galleries above the Whispering Gallery that encircle the outside of the dome of the cathedral. At 53m high, the gallery’s exposure to the elements and surface deterioration had caused water ingress damaging artwork inside the Dome. Sussex Asphalte’s craftsmen replaced asphalt originally laid in 1906 with IKO Permaphalt, a specially formulated, polymer-modified mastic asphalt. Works were phased to ensure continued public access and the asphalt was stripped and re-laid in sections to ensure watertightness. During the process a disused stairwell was revealed, which remains as a feature, having been made safe by the contractors.

The gallery includes a central gutter covered by iron grills that were removed, cleaned and refitted on the new asphalt. To ensure the correct width of asphalt was applied, a gutter template was fabricated and used as a guide by the asphalters. Other detail work involved adjustments to rainwater outlets to improve drainage, and vertical upstand into a chase, including a double angle fillet around the gallery’s circumference – 286 linear metres!

The height and highly-sensitive fabric of the building meant that all materials were transported to the gallery via three hoists, requiring careful operation and management. The works were completed ahead of schedule, and the overall project was so successful, Sussex Asphalte arranged a site visit for a large group of surveyors to promote the roofing profession.