Fibre Cement Slate

Defect and Repair

Weathering of Roof Tile

Seasonal weather changes can be tough on any type of roof.

To understand how roof tile weathers, one must become familiar with the different techniques that manufacturers use to color concrete and clay roof tiles.

Efflorescence

Efflorescence is a temporary condition that produces a hard white deposit on the surface of concrete tile. It is a naturally occurring phenomenon common to all concrete products; however, it is superficial in nature, meaning that in no way does it affect the quality or functional properties of the tile.

The process is caused by the chemical nature of cement. Manufactured cement contains free lime, and when water is added, a series of chemical reactions take place that cause the release of calcium hydroxide. This reaction can appear as an overall chalky bloom (a softening of color) or in more concentrated patches as a white chalky crystalline salt deposit on the tile surface

In most cases, the action of carbon dioxide and rainwater will gradually remove the deposit, leaving the original color of the roof intact.

Cracks

Cracks can be due to thermal expansion or not properly design movement joints.

Poor jointing and coating

Poor workmanship that can lead to leakage

Algae

Black streaking mark caused by algae growth and poor maintenance. The black streaking typically found on homes in areas where moisture settles on shingles is not caused by mildew or fungus; it’s roof algae.

Proprietary anti algae substances can be used uniformly distributed across the surface of the shingle, provides optimal, long-term protection from granule discoloration due to algae

Note: For more defects, please refer to the Defect Library.