3. Waterproofing principle for interlocking clay roof tiles

Interlocking tiles are rectangular tiles with grooves and ribs on their longitudinal and transverse edges, creating an interlocking device that holds the tiles together. Standard NF P31-301 of July 1985, "Tuiles de terre cuite à emboîtement ou à glissement", specifies that the minimum height of these ribs must not be less than 3 mm. By enabling tiles to fit together and overlap, these grooves and ribs also channel and drain water, ensuring the watertightness of the constructions they cover. They not only prevent rainwater from running down the roof, but also prevent water from rising up through capillary action.