Efflorescence

Efflorescence is a natural process that occurs in all cementitious materials. During and after manufacture, the cement in concrete tiles, mortar beds, and pointing compounds contains soluble calcium and sodium salts. When rainwater or moisture within the tile dissolves these salts and carries them to the surface, the water evaporates and the salts crystallise as a white, chalky deposit. Primary efflorescence occurs during the initial drying and curing of new concrete products and typically diminishes over the first year. Secondary efflorescence can occur at any time when external moisture penetrates the tile body. Efflorescence on roof tiles is primarily an aesthetic issue — the white deposits contrast sharply with the tile colour and give the roof an aged or neglected appearance. However, persistent efflorescence can indicate a moisture problem, as it requires ongoing water movement through the tile to transport the salts. In severe cases, sub-florescence (salt crystallisation within the tile body rather than on the surface) can cause spalling and surface deterioration of the tile. In Gippsland, efflorescence is commonly observed on concrete tile roofs, particularly in the years following installation or after re-bedding and re-pointing work using new mortar. Town & Country Roofing addresses efflorescence during roof restoration by removing the surface deposits during high-pressure cleaning and then sealing the tile surface with a primer and membrane coating that prevents moisture movement through the tile body.