If your aluminum siding is starting to look grungy and tired or you simply want to keep up with yearly maintenance, you probably want to know the best way to clean it. Using the right products and procedures makes a big difference in the outcome. Follow these five basic steps to make your aluminum siding look sparkly clean:

1. Check For Loose or Damaged Siding Panels 

  • Inspect for loose panels, gaps, holes, or other damage to be sure moisture, insects, and/or vermin have not entered behind the siding.
  • Make any necessary repairs before cleaning.

2. Check the Siding for Stains

  • Look for black, green, or gray stains, especially on north-facing walls. These stains are signs of algae, mildew, or mold. You’ll need to use more than just soap to destroy those lurking stains.
  • Pressure washing with a mild cleanser may seem like a good way to get rid of pesky stains, but algae, mold, or mildew will grow back if you don’t remove them with a stronger cleaner (see #5 below).

3. Prepare the Building and Property

  • Tightly close all windows and doors. 
  • Cover and protect any plants near the siding that may get damaged from cleaning agents or pressure washing.
  • Cover outdoor light fixtures with plastic bags and tape closed.
  • Cover electrical outlets with duct tape.
  • Move everything away from exterior walls such as outdoor furniture, barbecues, and decorative items.

4. Wash the Aluminum Siding 

Decide whether you’re going to pressure wash or soft wash the siding. Pressure washing is faster but requires some skill and knowledge of the machine so you stay safe and avoid damaging the aluminum siding. Soft washing is more labor-intensive but safer and allows for more protection of the aluminum siding. Let’s look at a few more pros and cons of each and the methods involved:

Pressure Washing

  • Know Your Pressure Washer!: If you want to pressure wash your aluminum siding but don’t own a machine, you can easily rent one at your local home improvement store. It should produce a pressure of at least 2,000 psi and you’ll use the fifteen-degree to twenty-five-degree nozzles. Pressure washing can be hazardous so be sure of the safety precautions before you use the machine. If the siding is painted, cover the ground with a tarp to collect any paint chips. Avoid pressure washing if your siding is painted with paint containing lead. Call your local health department if you’re unsure.
  • Protection: Wear protective eye covering, long sleeves, long pants, and strong footwear. Make sure children stay safely away and inform them that a pressure washer can be dangerous. 
  • The process: Start at the top and work in a 4- to 5-foot wide section at a time. Proceed carefully since using too high a pressure or too fine a nozzle can damage, dent, or peel off the siding’s finish. If the low pressure is removing dirt and grime, great. If not, wet the siding with low pressure then gently scrub with a cleaning solution and rinse with low pressure. If you decide to use high pressure, test a section of siding that isn’t visible, knowing that it’s possible the section could be damaged from the high pressure.

Soft Washing

  • If pressure washing seems too harsh, you can soft wash the aluminum siding with a garden hose, bucket, gentle brush, and cleaner. 
  • It may seem like more work at first, but it isn’t nearly as hazardous and you’ll be more confident that you, your landscaping, and your siding won’t get damaged. 
  • Use a paint roller extension handle, RV brush, or pool brush to reach the high areas. 

5. Choose the Best Cleaner for Cleaning Aluminum Siding

Mildew, pollen, dust, dirt, pollution, chalking, stains – they all can make the aluminum siding look grungy. It would be great if there were one single product that could tackle all the grunge, but since each problem is caused by a different chemical or environmental interaction, you’ll need specific cleaning agents for specific types of build-up. Let’s take a look at which products are used for which problems when cleaning aluminum siding:

To Remove Surface Dirt, Dust, and Pollen

  • For dirt, dust, pollen, and other surface debris use a general-use biodegradable detergent. Dish soap is fine.
  • Add the detergent to the pressure washer soap tank or to a bucket and mix with water.

To Remove Green Algae and Mildew

  • Add bleach to the detergent to enhance algae and mildew removal. You can use any commercial siding cleaner – many use bleach to activate the product. Warning: NEVER mix bleach with any product containing ammonia.
  • Hydrogen peroxide is a good alternative to bleach. It’s less toxic than chlorine bleach and easier on plants, your skin, and clothing. 

To Remove Oxidation and Chalking 

  • If you see a chalky residue on your hand after swiping across the siding, you know that the siding is oxidized. Simply pressure washing the siding won’t remove the oxidation. You need to use special products that are specifically made for oxidation removal. 
  • Vinegar can remove oxidation from aluminum siding. First, use a household detergent mixed in water to clean the aluminum siding of dirt and debris. Rinse the siding well. Now add ¾ cup of vinegar for every gallon of water and scrub gently. Be sure to thoroughly rinse the vinegar solution from the siding. Vinegar can damage aluminum siding if it’s left on too long or not thoroughly rinsed off. 

Using TSP to Clean Aluminum Siding

  • Trisodium Phosphate, or TSP, is so strong that it can strip paint from a surface. It’s a serious dirt dissolver but it’s toxic to the environment. If it ends up in streams and lakes, TSP can trigger algae overgrowth, which depletes oxygen levels and kills fish, water fauna, and flora. For this reason, TSP is no longer recommended for jobs like cleaning any kind of siding. Check your local regulations to see if TSP is permitted or banned in your area. 
  • When TSP is added to bleach, it eliminates mildew and mold. Be aware that this ultra-strong mixture can fade the siding’s finish. Test it out in a small area first to see how the siding reacts. Although it’s not recommended, if you do use TSP, be sure to wear protective gear.

Using Borax to Clean Aluminum Siding

Borax is a safer alternative to TSP. Known as sodium borate, borax is a naturally occurring mineral compound that is antimicrobial and cleans many of the same surfaces that TSP can clean, including mildew and mold-stained surfaces. It doesn’t harm plants and landscaping like TSP can.

A Note About Cleaning Aluminum Siding Before Painting

Dirt, dust, pollen, mildew, algae, and oxidation absolutely must be removed before the aluminum siding is painted, otherwise, the paint won’t adhere properly. Thoroughly cleaning aluminum siding before painting makes a huge difference in the lifespan of the paint you apply. 

Choosing Professional Help

If cleaning your aluminum siding seems tricky or too difficult, a pro can quickly and easily do it for you. Pros know how to repair any damage to the aluminum siding before it’s cleaned and they know which products will remove oxidation, mildew, and algae. They have experience with pressure washers and know the proper methods to use so your siding won’t be damaged. Plus, they bring all the materials for the job, protect landscaping, and will have the work done quickly and efficiently. 

Don’t get overwhelmed trying to find reliable help to clean your aluminum siding. Clad Siding makes it easy to find the right people to do the job. We’ll quickly connect you with licensed and trustworthy siding contractors in your area who are experts at repairing and cleaning aluminum siding.


Cleaning siding is a lot of work but finding the best help is easy with CLAD Siding. Get your free quote now!