Efflorescence on concrete tiles

A whitish substance appears on the surface of concrete tiles

Causes

Natural salts within the tiles migrate to the surface leaving a whitish-grey residue

Listed under: finishes, tiles, concrete and cement, concrete tiles, Roof, cladding, roof cladding, concrete or clay tiles

Cause

Natural salts within the tiles migrate to the surface leaving a whitish-grey residue

Repair

  • the appearance of efflorescence is a normal process where calcium carbonate crystals form on the surface of uncoated tiles, giving the appearance of a whitish haze

  • efflorescence generally becomes less visible through natural weathering processes. Rainwater, being slightly acidic, dissolves and washes away the deposit over time

  • efflorescence does not affect the durability or longevity of concrete tiles

  • some concrete tiles are manufactured with a polymer coating designed to help suppress the appearance of efflorescent salts early in the life of the roof. The polymer coating has a typical lifespan of around 3–5 years, after which it has weathered away

  • apart from efflorescence, manufacturers’ literature makes it clear that the appearance of concrete tiles will change over time, becoming duller. This is completely normal and does not affect weathertightness

  • if the efflorescence does not disappear or there are other problems with the appearance of the tiles, contact the supplier or manufacturer for advice

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