Interlocking Clay Tile

An interlocking clay tile is a fired clay roof tile with raised ribs and channels along its edges that hook into matching grooves on the adjoining tiles. The interlocks guide water away from the joints, allow a single-lap layout, and reduce the number of tiles needed compared with plain or two-piece curved tiling.

Origins

Interlocking clay tiles date to the 1840s. The Gilardoni brothers of Altkirch, in Alsace, France, began making them in 1835 and patented their first design in 1841. In English the type is often called the "French tile" or "Marseille tile". In Germany, Wilhelm Ludowici developed his own influential interlocking design in 1881. Large-scale production of interlocking tiles required the mechanical tile press, which shaped damp clay between steel dies.

Global spread

In India, the Basel Mission tile works at Mangalore, founded in the 1860s, first followed the Gilardoni design and later the Ludowici pattern. "Mangalore tiles" became standard across the west coast of India and were exported throughout the Indian Ocean region.

Features

• Single-lap coverage, giving a lighter roof than double-lap plain tiling.
• Side and head interlocks that resist wind-driven rain.
• Nibs on the underside for hanging on battens, and often nail or clip holes for mechanical fixing.
• Profiles range from nearly flat with shallow ribs to deeply curved interlocking pantiles.

Concrete versions

Concrete tile manufacturers adopted the same interlocking principle, and many concrete tiles reproduce clay interlocking profiles.

Named patterns

Besides the generic French or Marseille tile, designs such as the Ludowici and Conosera tiles are listed among the main interlocking types. All rely on precise pressing so that the ribs and grooves of neighbouring tiles fit closely.