Every roof has a different level of dirt and hence, requires a different way of cleaning. The easiest way is to use a high-pressure water blaster for a rough surface. You can also use a broom for smooth surfaces. For dealing with ingrained stuff like mold and algae, you will need some types of roof cleaning chemicals.
Apply the chemical deep into the pores; let it sit for a while and it will rinse it naturally next time it rains. Need to repair and paint the roof? You can hire roof painters from one of the top roofing companies in long island who specialize in roofing construction.
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For a new iron roof, wash it with a degreaser to undo the effects of oil fabrication and weathering. For unpainted iron roofs, paint it with primer first. Then give two coats of selected paint. The color choice is totally yours. But remember, light colors reflect the heat and darker colors absorb the heat.
Though some tile roofs start looking almost brand new water cleaning, painting really revives them. In this case, you need to prime it first and make sure you apply plenty of primers. After that, give two coats of the suitable paint. For painting tiled roofs, you can also use brushes, but it would take a long time.