BCD 2017

T H E B U I L D I N G C O N S E R VAT I O N D I R E C T O R Y 2 0 1 7 161 INTERIORS 5 mechanical damage, revealing the inner core material and many have become detached from their backgrounds. It is apparent from visual inspection that the past replacement of tiles has been extensive. Individual tiles are known to have been replaced in the 19th century, while in the 20th century some areas were completely re-laid with new tiles and stone flags because of bomb damage during the second world war or because they had worn away. Minton tiles ceased production in the 1960s and new tiles for repairs after this date came from various sources and were often not a good match for the originals. Wear and tear had worn many of these replacement tiles beyond temporary repair and in many areas the damaged tiles had become a trip hazard. The Palace of Westminster is a working building with about one million people entering it every year and it is not possible or desirable to re-route the members, staff and public away from the tile floors. In considering new approaches to the repair and conservation of the floors and assessing the results of a small amount of repair work done in the late 1970s and early 1980s, as well as trial areas laid in 1998 and 2004, the following points were evident: • The differences in artwork quality in the reproduction of original designs tended to disrupt the continuity of pattern across the floor. • Replacement tiles used in the later 20th century were 13mm thick – around half the thickness of the Minton originals – and were designed to be laid on a hard mortar bedding as a floor finish. The original construction of 25mm (1 inch) tiles laid in soft mortar had a monolithic quality able nevertheless to accommodate movement without cracking. • Temporary repairs had been carried out using coloured epoxy resins, introducing both visual disharmony and guaranteed failure. At an early stage, different strategies for the conservation and repair of the floors were identified and assessed as follows: • Do nothing, except repair for safety reasons. This would reduce the risks of accidents while retaining the historic fabric but it would not conserve the original fabric and would not address the significant aesthetic issues of the worn tiles. • Leave the tiles as found and cover them with duck-boarding or carpet. This might prevent future wear but would also drastically undermine the architectural integrity of the pavements as originally intended and, at the same time, introduce new and incongruous elements to some of the most important areas in the palace. • Completely remove existing tiles and re-lay using new tiles not matching the originals. The gains in safety and durability offered by this line of action would be substantially outweighed by the loss of historic fabric. • Completely remove existing tiles and re-lay using new specially made replica encaustic tiles to match originals in colour, shape and pattern. This would both retain the original design of the floors and provide a new and durable level floor free of defects and unevenness. The disadvantage is that it would result in the loss of much historic fabric that might otherwise be retained and repaired. • Locally replace tiles and stone flags according to a critical methodology based on the selective assessment of the condition of both the existing tiles and the associated stonework. This option would retain the historical integrity of the building, prolong the life of the original tiles, guarantee the durability of these heavily trafficked pavements and give an appearance of consistency. The last option was considered the most appropriate. Heavy footfall in the building made frequent repairs to the tiles necessary. This precluded repairing the tiles in situ using, for example, plastic repair methods. Rather, damaged tiles would be replaced with new ones in close facsimile to the originals in terms of visual appearance and physical qualities. On balance, it was considered that the extensive replacement of tiles that this would entail would be acceptable as an alteration to the historic fabric. This conclusion – that the significance of the design of the pavements is more important than that of their fabric – was reached by reasoning that: • The long history of repairs to the encaustic tiled floors makes it impossible to identify with certainty tiles that are original against those that have been replaced. • The loss of decorative pattern over large areas of the pavements due to their excessively worn condition detracts from the overall presentation of the highly significant interiors of which the encaustic tiles form a major part. Before comprehensive proposals for repairing the encaustic tiled floors could be brought forwards, a combination of site surveys and investigation and a trial repair was necessary. A full photogrammetric survey was made of all floors before work began and a photographic record was made of each stage of the processes which followed. Opening up was undertaken in discrete areas of the floors in St Stephen’s Hall and the Members’ Entrance in order to clarify these issues. This confirmed that the tiles were originally bedded and pointed in a moderately hard mortar in a single operation. The tiles, which are one inch thick, have slightly canted edges to facilitate laying in this manner. In all cases, a very hard grout appeared to have been applied subsequently. Bases included York stone flags and weak cement screed over rubble infill. Samples were taken of all mortar and screed materials for laboratory analysis and tests confirmed that the original bedding and pointing materials contained an early Portland cement. Product development to produce a tile of one inch thickness started in 2008 and was undertaken in conjunction with Chris Cox of Craven Dunnill Jackfield at Ironbridge, Shropshire. Practical tests included undertaking development work in order to An original hand-operated tile screw press, Gladstone Pottery Museum, Longton, Stoke-on-Trent Worn tiles, St Stephen’s Hall Carving the pattern to form a plaster tile mould Pouring coloured slip clay into a mould