Creosote is a highly flammable material often found inside chimneys. Produced by things like wood-burning stoves or fireplaces, that creosote can also build up on composition asphalt shingles. When ash comes out of the chimney, the breeze can actually carry it along the roof. When this settles in a layer over your roofing shingles, it puts your roof at risk of fire. One errant ember from your chimney could cause a serious disaster. If you see black stains along your roofing shingles, that's a sign that it's time to clean the shingles to protect your house.
Steps for Cleaning Your Shingles
Protect the Property
Start by protecting your landscape from the debris of the cleaning process. Spread drop cloths over all of your border shrubs and plants around the perimeter of the house. This protects all of your greenery from the splatter of the cleaning solution and the creosote debris.
Create a Cleaning Solution
Mix about a cup of oxygen bleach into a gallon of warm water. Stir the mixture to ensure that the bleach mixes thoroughly. If you're using a granular oxygen bleach, make sure it dissolves completely in the water. It has to be thoroughly dissolved and completely integrated into the water before you use it.
Clean the Roof
Put the bleach cleaning solution into a hand-pump sprayer. Don't use a pressure washer, because the amount of pressure behind the water could damage your roofing shingles. Instead, spray the whole roofing surface with the cleaner using a hand sprayer. This ensures even distribution and saturation without damaging your roof.
You'll probably want to use a secure ladder to do this so that you can reach the roof easily. It's often safest to have someone on the ground to keep the ladder stable. Work your way around the whole roof to make sure that everything is sprayed with the cleaner. Then, use your garden hose fitted with a low-pressure spray nozzle to rinse the whole area.
The more thoroughly you rinse, the better. It's best not to leave any residue of bleach solution on the roof at all. If necessary, go over the whole roof twice with the hose to ensure that it is rinsed. Then, allow the roof to dry. If you do this on a sunny day, it will dry quickly from the heat of the sun. The faster it dries, the less risk you'll have of any mold growth or mildew left behind on the roofing tiles.
If you aren't comfortable cleaning the roofing shingles on your own, consider talking with a roofing contractor such as Independent Roofing Inc about cleaning the whole roof for you a couple of times a year. This will keep creosote buildup off the roof and protect your home from an unnecessary fire hazard.