Concrete roof tiles are usually only cleaned when the intention for after is to re-seal and re-paint/coat the roof tiles surface.
There have been various makers of Concrete/Cement roofing tiles over the years. Some have performed very well whilst others have performed poorly, creating more issues for home owners than originally intended.
The reality is that Concrete tiles do in fact deteriorate over time. The general idea is that Concrete cures and hardens over time, which is true, however for Concrete roofing tiles the curing process lasts around 12 months from the time the tile is created.
Concrete tiles may also develop structural defects if they are moved onto trucks and roofs, and chances are they’re not left alone to completely cure before being used. These defects mainly show up many years after the tiles are installed and cannot be rectified.
Concrete roofing tiles generate about 120 degrees of surface temperature, where the ambient daily temperature is 30 degrees (most summers). As a result the tiles surface takes a hammering year in year out, with other things such as acid rain, wind and pollution all contributing to the wear and tear of the concrete tiles surface.
Initially, the tiles surface will oxidise and become quite powdery; once the surface coating is gone, the sand cement component of the tile also becomes affected by way of erosion.
The surface of the tiles end up in the surrounding gutter system and will soil in the gutter, limiting the flow of water to the gutters, down pipes, water tank and eventually gives cause for the gutters system failing.
A good quality sealer and coating application will stop the tiles surface from deterioration, with a new colour also dramatically enhancing your roofs appearance.