The growth of Algae Mosses & Lichens on Tiled Roofs

During cold spells, especially in winter, ice-dams can form on top of clogged gutters. Then snow builds up across the top of the gutter and freezes.

As the temperature warms, thawing water running off the roof is blocked by the frozen water and can escape into the house. This can lead to major wall and ceiling damage internally.