How to Clean Metal Roofs

Properly maintained, a quality metal roof can last for a lifetime. To ensure that your roof stays in top condition, a regular cleaning is suggested. This is particularly important if your roof is in an area that lends itself to the buildup of mold or mildew. Not only will your roof's paint stay in better shape, but the look of your house will be enhanced and it's overall value or resale value improved.

Things You'll Need

• Power washer
• Ladders
• Cleaning supplies
• Brushes

Instructions

How to Clean Metal Roofs

1. Assess the condition of your roof. An old roof, with excess paint and corrosion will require extra steps in preparation, cleaning, and restoration. A relatively new, or well-cared for roof will require less work. Evaluation of the work at hand is important in doing a good job cleaning the roof. Cutting corners will cause more work later.

2. Ensure that you can safely work on the roof, and reach all the areas you wish to clean with ease. If necessary, wear a safety belt, attach a rope, and belay to a solid support to prevent accidental falls off of the roof.

3. Scrape away any excess paint or corrosion if necessary. A wire brush will be necessary for this step. Do not use metal implements on the roof unless absolutely necessary. If you find that you must, a flat-bladed putty knife will handle most paint-scraping tasks. Do not scrape the paint unless it is necessary to remove excess paint build-up or chipping or peeling paint.

4. Prepare a solution of TriSodium Phosphate (TSP) (available at most paint stores) and water, mixing 1/2 cup per gallon of water. Take the solution to the roof in a large bucket. Using a soft brush, apply the TSP to any mold or mildew covered areas, scrubbing until clean. Do the entire roof this way if it is excessively dirty. While this is time consuming, it is the best way to ensure a thorough cleaning. Rinse the areas you've worked on with water, to make sure you don't leave any residue behind. Allow the roof to dry and evaluate the cleaning stage. Repeat on problem areas if necessary.

5. Spray the entire roof with a power washer. Start at the top and work your way down so that dirt and debris is carried away as you do the washing. Maintain a uniform distance of the sprayer from the roof as you work the sprayer nozzle back and forth, across the roof, going from top to bottom. Plain water is fine for most applications. However if the roof is especially dirty, a mild detergent may be added to the sprayer. Keep the solution mainly water, to avoid sudsing and leaving a detergent film. If necessary, repeat the process of spraying, or rinse the entire roof with water when you're done.

6. If you had to remove corrosion or damaged paint in step 3, prime and paint those areas now. A standard metal primer is appropriate. Be sure to follow the instructions for preparing the metal to ensure a good bond between the primer, paint, and metal. Allow sufficient time for the primer to cure before painting. When you paint, be sure to match color carefully so your roof has a uniform look.

Tips & Warnings

• When using the power washer, spray from a consistent distance and work one section at a time.