4 Coleman Street

This project was awarded Highly Commended in the New Build category at the Natural Stone Awards 1997.

The official guide said, 'The building sits at the junction of Coleman Street and Basinghall Avenue in the City of London, where stone from the Dorset island of Portland has been used as a building material for centuries.

Portland Basebed stone from Bowers Quarry was selected for this project with the hard, French Villebois limestone for a plinth and ground floor cills.

The elevations of the building are dominated by the curved bay windows and the Basebed stone was selected for its uniform colour and texture so as bit ti detract from the clear, strong lines, with a more traditional granite, used for the plinth to soften the contrast between the stones.

Two coats of tar waterproofing RIW were applied to concrete walling of the building before stone fixing began. The 140mm-thick French Villebois constituted both the plinth course and two more courses above. The stone was dowelled and restrained back to the blockwork with a damp-proof course detail behind. The fourth course was Portland Basebed, 100mm-wide with an 80mm-wide-hen-pecked feature band.

There followed 75mm-thick Portland cladding with a fluted band course interspersing on the third floor. The builders, Trollope & Coll, had inserted stainless steel channels into the concrete for the stone fixings, to reduce drilling into the structure.

Ledumite grade two was fixed around the windows before the stone was fixed and Rockwool insulation was fixed behind the cladding. The stone was fixed clean, allowing a pointer and finisher to come behind to strap point and clean the stone.

When the construction reached the top, the stone was sanded first with a 24 grit disk pad, then a 36 grit, with restorers and finishers again following behind.'

The judges commented, 'Set at an important corner site in the city, this building makes an immediate impact by the use of expressed curved bay windows. The balance between straight and curve together, with solid and void, is well handled and makes a favourable impression. Equally impressive is the consistency of the high standard of site control and workmanship. The clean, clear lines of the Portland Basebed used for the bulk of the building are enhanced by the use of a soft brown Villebois French limestone for the plinth and lower cills.'

To view this project in more detail, please click here.

Portland Stone used at Coleman Street