Unsightly stains on your roof aren't pretty, but they can also cause damage if left too long. The stains might be mold, algae, or even the result of other organic materials that come into contact with your roof. The good news is that it isn't difficult to fix the problem on your own without too much trouble. All you need is a great cleaning solution and a little bit of time to let it do its work.
Choose the Right Time
Whenever you clean your roof, you have to choose the time and day carefully. Family Handyman recommends checking the weather forecast and opting for a day with partial cloud coverage and low projected wind. This helps in two ways. First, you're less likely to accidentally spray your neighbor's roof, and second, the cleaning solution has a better chance of working on the stains rather than drying almost immediately after spraying.
Prep a Cleaning Solution
Mix warm water, a tablespoon of low-sudsing detergent, and 1/2 cup bleach in a garden sprayer. Don't fill the sprayer all the way to the top because the warm water can cause pressure to build up in the sprayer. Leaving some room in the body of the sprayer allows space for some of that pressure. Prime the sprayer and get ready to attack those stains.
Let the Cleaning Solution Sit
Once you spray the cleaning solution onto the stained parts of the roof, let it sit for at least 15 minutes. Keep an eye on the sprayed area and if it does start to dry before the 15 minutes are up, spray the area again. Work on small areas at a time, so it's easier to see whether or not the cleaning solution is working.
Scrub the Roof
Once the 15 minutes are up, use a stiff-bristled brush or a broom to scrub the solution into the stain. Apply additional cleaning solution as needed while scrubbing the roof. Once the stain is removed, rinse the cleaned area of the roof with fresh water. Check the area to make sure the stain is really gone and move on to any other stains that need your attention.
If your roof needs more than just a little bit of extra cleaning attention, contact a professional roofer today. He can assess the current condition of your roof for you and either make the necessary repairs or put a new roof in place.