Almost without exception, slate problems occur where snow, moss or algae has lain on the slate surface for prolonged periods. In cases where trees are not hanging over a roof, the surface is problem free (trees create a fertile environment beneath them that fosters moss, algae and lichen growth which holds moisture and snow in place). In winter as the daytime sun melts some of the snow, the water falls into the slate through fissures and cracks and absorbs into the slate. At night it freezes and expands, widening the cracks and pores, providing larger cavities for the next days melting water. The cycle continues with tremendous expansion and contraction of the slate around the cracks. A once strong and solid surface has become broken and flakey. This situation will requires expensive repair or replacement. The best way to eliminate or reduce this problem is to eliminate the algae, moss and fungus.

The process begins with detergents, mildewcides and a neutralizer are applied in three separates steps. A high pressure wash is then used to remove material from deep in the pores. No amount scrubbing can even come close to these results. Tree sap, pollen, leaves, etc. just settle on your patio / masonry work. All of these very natural materials form a very rich fertile mixture for mildew, algae and moss to grow on and that’s fine ….in the woods.