The Building Conservation Directory 2023

160 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 2 3 | C E L E B R AT I N G 3 0 Y E A R S C AT H E D R A L C O M M U N I C AT I O N S The spectacularly tiled entrance hall to Coleridge Chambers, Corporation Street, Birmingham by John W Allen of West Bromwich, 1898: the floor is paved with unglazed encaustic tiles and mosaics; coloured translucent glazes give form and depth to the embossed wall tiles and the moulded skirtings and dado rails; while the floral wall tiles include printed transfer decoration. DEFECTS AND VULNERABILITIES Ceramic tiles are brittle and are liable to fracture with changes in the substrate, or if hit hard by a heavy object. Substrates supported by timber floors and partitions are likely to result in some movement, but all substrates are vulnerable as they age. Wall and floor tiles can become detached, whether as a result of impact or through movement in the substrate, and wall tiles are likely to smash when they fall off. Wear is another problem. The surface of floor tiles is worn down over the years by the passage of feet and by the abrasive effects of grit and dirt brought in on shoes. In the most heavily trafficked areas, the inlay of encaustic tiles, which may be no more than 2mm deep, is likely to be slowly worn away, as happened in the corridors of the Houses of Parliament. Some tiles may suffer inherent defects arising from the manufacturing process. The most common of these are variations in the contraction rate of the clay body and the glaze which cause crazing. In the worst case this can lead to separation of the glaze from the body, but usually crazing is harmless apart from the fact that it will be more porous. Crazing may also be caused by the expansion of the clay body when wet. This may also affect adherence to the bedding mortar, and tiles may become loose after a flood. Further defects and repair approaches are discussed in some detail in Historic England’s Practical Building Conservation volumes Earth, Brick & Terracotta . However, it is important to note that cements and adhesives used in the repair of tilework must allow some movement because tiles expand and contract with changes in moisture levels. This means that the repair methods commonly used by contractors today are likely to fail as they cannot accommodate seasonal movement. An article to be published in Historic Churches will explore these issues further. New replica encaustic tiles by Craven Dunnill Jackfield in the central lobby of the Houses of Parliament being ceremonially tapped by the Speaker of the House of Commons: the originals had been made by Minton’s to the designs of AWN Pugin by 1852, but their decoration had worn away under heavy foot traffic. (Photo © UK Parliament: Jessica Taylor)