When moss is removed from a slate roof it will dramatically improve the look of your house, it gives a great first impression to the rest of your home. When moss and lichens are left on the slate it will over time become porous, holding onto moisture and look and feel less smooth.
The way a slate tile roof should be cleaned depends entirely on the debris build up. The roof videoed below was prepared by removing the bulk of the debris and moss by hand using a handheld scraping tool and then a non aggressive treatment was applied to the tiles which begins to work immediately in killing the biofilm.
The treatment will continue to work over a period of time with the weather giving it a helping hand, these results aren't seen immediately but once they've started working in removing the biofilm the tiles will start to self cleanse. The bonus with this approach is not only is it a lot less harsh on the roof tiles but it also offers protection from re growth for many years to come.
Why should I remove the moss from my slate tiled roof?
Cleaning your roof regular is very important to keep your slate roof in good working order. When moss builds up it acts like a sponge holding onto moisture which can easily lead to the tiles splitting during the winter months when it freezes over.
Slate is a sedimentary rock with minuscule layers that easily split. This quality is what distinguishes slate as a suitable roofing material. Once turned into roofing material, slate absorbs water and can naturally de-laminate during the freeze-and-thaw cycles of winter.
A slate roof should last a lifetime, flashing and fasteners etc are often the highest quality so they don't fail before the slates need replacing.