Leaving aside the aesthetic consideration, dirt and biological factors can favor serious damage to the structure of the tiles and to the entire building system.
Although many modern roofing materials have a fairly long warranty (a few decades!) and are designed to be water, fire and frost resistant and impregnated with anti-algae solutions, they all become to deteriorate sooner or later.
Dirt that builds up on the roof is a perfect environment for bacteria, moss, algae or molds that clog the spaces between tiles and other coating materials and favor the apparition of roof leaks. Dirt between the tiles also absorbs water, keeping it on the roof longer than it should, and prevents its natural drainage through gutters and downspouts, ultimately damaging the structure of the roof.
Clean roofs absorb or reflect the heat of the sun and are made of materials that ensure not only protection against weather, but also thermal insulation of the building. If covered by dirt or vegetation, roofs lose their ability to adjust indoor temperature and maintain adequate thermal comfort.
Cleaning the roof is not as simple as many people think. If you do not have the minimum knowledge but you still venture to clean the roof yourself, you risk damaging roofing materials. Therefore, it is best to make from roof cleaning a regular operation, performed by the Lakewood roofers specialists who periodically inspect and maintain your roof.