How to Clean Aluminum Siding | Restore Your Home’s Exterior

Aluminum siding is durable, but dirt, mildew, and oxidation can dull its appearance over time. The right approach restores the finish without damaging the metal or its paint. The best method depends on how dirty your siding is and whether you plan to repaint.

What You Need to Clean Aluminum Siding

Gather these tools before starting to keep the job efficient. Using the wrong brush or nozzle can scratch or dent the panels.

• Garden hose with an angled spray nozzle
• Soft-bristle siding brush with an extension pole
• Large bucket or a chemical sprayer
• Mild detergent or siding-specific cleaner (Simple Green’s aluminum siding cleaner is one option)
• Protective gloves, safety glasses, and a face mask
• Plastic sheeting to protect nearby plants

If your home was built before 1977, test for lead paint before any scrubbing or scraping. Wear protective gear regardless, as old siding may contain loose particles.

Step-by-Step Manual Cleaning

Manual cleaning is the safest method for painted aluminum and works well for routine maintenance. Work on a calm, dry day and never let the cleaner dry on the surface.

1. Pre-rinse the siding from top to bottom with a garden hose to remove loose dirt and pollen.
2. Mix your cleaning solution. For general grime, combine 1.5 cups of mild detergent per gallon of water. For mildew, use a 1:1 mix of water and white vinegar or bleach — but skip bleach if the siding is colored, as it causes fading.
3. Apply and scrub in sections. Work in 4-foot-wide areas. Apply the solution from bottom to top, then scrub firmly with a soft-bristle brush. This order prevents dirty water from streaking over clean areas.
4. Rinse thoroughly from top to bottom using the hose, directing debris downward. Avoid spraying upward — water trapped behind siding can cause rot or interior damage.
5. Inspect after drying. Check under siding lips for missed spots and repeat or spot-scrub if needed.

For a full comparison of the best cleaning products available today, check out our roundup of the top-rated cleaners for aluminum siding.

When and How to Use a Pressure Washer

Pressure washing is faster but riskier. Aluminum dents easily, and high pressure can dislodge panels or push water behind them. Use a 25- to 40-degree nozzle and maintain at least 18 inches of distance, always angling the spray downward.

Apply the cleaner from bottom to top using the low-pressure detergent setting, let it sit briefly without drying, then rinse from top to bottom with higher-pressure water. Be extremely cautious around windows, doors, and plumbing penetrations.

Common Mistakes to Avoid

• Hot water: Never use hot water on aluminum siding — it can warp the metal, especially on thin panels.
• Bleach on colored siding: Bleach effectively removes mildew and pollen but fades painted panels. Use it only on white or unpainted areas.
• Scrubbing too aggressively: Steel wool or stiff brushes scratch the finish. Stick to soft-bristle brushes.
• Skipping plant protection: Chemical residues harm landscaping. Cover plants with plastic sheeting before applying any cleaner.