The best time of year for roof cleaning depends on your local climate, but generally, late spring, summer, or early autumn are ideal. Plan to clean your roof on a day with dry weather and moderate temperatures.

Late spring and early summer are excellent for cleaning off grime accumulated after a snowy winter or wet spring. Summer often provides the necessary dry conditions, though in very hot climates, late spring may be more comfortable. Alternatively, cleaning in late autumn can clear away debris like leaves and branches before winter.

Avoid cleaning your roof when it is cold enough for water to freeze, as this can cause dangerous ice buildup.

You may become so frustrated with the look of moss on your roof that you contemplate whether to clean or replace your roof. Fortunately, you don’t have to go as far as replacing it. After cleaning the moss, you can use a chemical solution to keep it away. For further protection, trim branches that overhang the roof, as fallen seed pods and leaves on the roof allow moisture to collect, encouraging moss growth. Consider adding zinc-coated flashing to the roof, too. As rain washes across the zinc, it leaves zinc particles behind that inhibit moss growth.

A green roof is a roof design that includes a thin layer of vegetation on the roof surface. It’s an environmentally friendly option. Some green roofs may look like they have moss or algae on them, causing neighbors to suggest that you clean the roof. However, you should never try to clean a green roof, as any cleaning methods you deploy will likely kill the vegetation.

Clean the outside of your home at least once a year. If you live in an area with salty sea air, high levels of pollen, or an abundance of leaves in the fall, it's helpful to wash it at least two times a year. Frequent cleanings will allow you to remove debris and pests before they flourish into infestations, or cause mold and mildew.