Copper roofing is a beautiful and elegant roofing choice, but generally it is only this way when it is new or cleaned to best show the copper color. If left unpolished, however, the beautiful copper color of the roofing will become hidden by a green patina. Copper patina, while created from corrosion, actually protects the copper beneath it from further corrosion. For this reason, when cleaning a copper roof, it is important to avoid removing or damaging the patina that covers it. You'll need special materials, tools, and instructions to effectively clean your copper roof without removing its patina.
Step 1 – Safety Preparations
Before working on your roof, make preparations for safety. Wear shoes with rubber or non-skid soles. Be sure your roof's surface is dry, and use a sturdy ladder that will allow you to climb safely onto the roof. Avoid working alone. Have a helper hold your ladder while you're climbing on it. If, while you're on the roof, you find that you need materials or tools from below, lower a rope from the roof and have your helper tie your tools or materials to the rope so you can bring them to you without having to climb down the ladder.
Step 2 - Mixing the Cleaning Solution
You'll need a special cleaning solution that will not damage your copper roof's patina but will help in cleaning off all dirt and debris. A solution that will work well is one made of lemon juice (3 parts) and coarse salt (1 part). To clean your roof you will need a relatively large amount of this cleaning solution. Therefore, when making the solution, mix the parts in quarts or gallons rather than cups. Three cups of this solution will not clean a surface as large as a roof.
Step 3 – Remove Loose Debris
Before applying your cleaning solution, be sure you remove all loose debris, such as leaves, twigs, and dirt, that might have collected on your roof. Not only will this make your work more safe by helping to give you more secure footing, but it is an important step in the cleaning process. Loose dirt will absorb your cleaning solution and will do little more than create a muddy mess. To remove debris, use a broom rather than trying to spray off the debris.
Step 4 – Scrub Your Roof
Use a scrub brush or push broom, moistened with your lemon juice and salt solution, to scrub your roof surface. You can scrub with the solution and a brush worrying about removing the patina. As you scrub, use a garden hose to rinse off the roof surface where you're working.
Step 5 – Apply Polyurethane
When you've finished cleaning your roof and when the roof surface is dry, protect the patina from weathering by applying a polyurethane spray.