Use of Clay Tiles in Floor and Wall Construction

Abstract

Although little used today, clay tile, otherwise known as terracotta tile, has been used in both floor and wall construction in times past. For engineers involved in restoration of older buildings, it may be helpful to record structural uses of this material as distinct from glazed decorative uses on building exteriors. The writer designed a large convent and high school complex in 1958 and more recently has been involved in the renovation of buildings of similar construction. Although the Oxford Dictionary defines terracotta as unglazed, brownish-red earthenware used chiefly as an ornamental building material, its most familiar and everyday form is in plant pots. The moldable qualities of soft clay or weathered red shale permit manufacture of cellular units by an extrusion process. Fig. 1 illustrates the cellular form. Typical sizes were 300 mm ~12 in.! square by thicknesses varying from 150 mm ~4 in.! to 250 mm ~10 in.! or even 300 mm ~12 in.!. The furring or partition tile used in the type of construction addressed in this article would have wall thicknesses varying between 16 mm ~0.625 in.! and 19 mm ~0.75 in.! due to the striations deliberately produced in the extrusion process. The absorbent striated surface could be plastered directly without the need of lath to key the plaster to the surface. Tile Joist Floors Fundamentally, this construction is similar to any concrete joist floor construction, the essence of which is a series of closely spaced reinforced-concrete tee beams spanning between bearing walls or beams. For tile joists, a complete floor form was required