How to Clean a Metal Roof (Safely, From the Ground)

When and why to clean a metal roof

A metal roof needs cleaning far less often than homeowners expect — it has no granules to shed and, in aluminum's case, no rust to treat. You clean mainly to remove dirt, pollen, organic debris, and, near the coast, salt spray, both to keep it looking good and to prevent mildew from taking hold in shaded, damp areas. For most homes an occasional rinse is plenty; homes under heavy tree cover or in coastal and dusty regions benefit from cleaning a couple of times a year.

The safe, simple method

The goal is a clean roof and a safe you — which means working from the ground. Rinse the roof with a garden hose to loosen surface dirt, then apply a well-diluted, non-abrasive liquid detergent with a long-handled soft-bristle brush, working gently from the top down so runoff doesn't re-soil cleaned areas. Rinse thoroughly with the hose to remove all detergent. That's it — no harsh chemicals, no scrubbing pads, and nothing abrasive that could mar the finish.

What to avoid

Two things cause most metal-roof cleaning problems. High-pressure washers can force water up under the panels and can damage the finish, so skip them. And walking on the roof risks both your safety and cosmetic marks on the panels — thousands of people are injured every year in falls from roofs and ladders. If a job truly requires getting onto the roof, or if staining won't come off from the ground, hire a professional with the right equipment rather than taking the risk yourself.

Step by step

1. Rinse the roof with a garden hose from the ground to loosen surface dirt and debris.
2. Mix a well-diluted, non-abrasive liquid detergent in a bucket.
3. Apply it with a long-handled soft-bristle brush, working gently from the top down.
4. Let it sit briefly on stubborn dirt or mildew, then agitate lightly — never scrub with abrasive pads.
5. Rinse thoroughly with the hose to remove all detergent residue.
6. Skip pressure washers and roof access — hire a professional for anything you can't safely do from the ground.