Gutters can become stained for a number of reasons, including overflowing gutters, mineral buildup or mould growth. Some types of stains such as black streaks, also known as tiger stripes, are caused by particles of algae, pollution, roofing material and/or dirt that become attached to gutter surfaces. Whatever the reason, stains on the outside surfaces of your gutters will mar their appearance, detracting from the neat exterior of your home. To restore the visual appeal of unsightly rain gutters, a gentle scrubbing is often all that is needed to remove surface grime.
Most stains can be removed with soapy water. In a pump spray bottle, mix 10 to 15 drops of dish detergent with hot water. If the stains are deep or persistent, you may have to use a cleaning product designed specifically to be used safely on gutters. For mould and mildew stains, add a small amount of bleach to your cleaning solution to kill spores and prevent further growth. Plan to work in sections at a time – apply solution, let solution soak in, scrub, and then rinse.
Liberally spray the soapy solution on the areas you want to clean. Let it sit for 3 to 5 minutes before wiping.
Re-apply soapy solution or spray plain water on a small part of the gutter. With a grout sponge, scrub the outside surface of the gutters. For more stubborn stains, use a scrub brush. You can also use a cleaning sponge like Magic Eraser to remove really tough stains.
Rinse away soapy residue with a bucket of water and clean sponge or a garden hose. Examine each section for missed spots. Wherever necessary, reapply more cleaning solution and rinse again.