How To Prep and Paint Aluminum Siding

Painting aluminum siding helps refresh your home’s exterior and extends its lifespan. This project requires effort, but it offers a cost-effective alternative to full siding replacement. In the video above, This Old House painting contractor Jim Clark demonstrates the proper techniques for cleaning and preparing aluminum siding for a long-lasting finish.

Preparing To Paint Aluminum Siding

Proper preparation involves inspecting the siding, gathering necessary materials, and cleaning the surface thoroughly.

Inspect the Siding

Start by examining your aluminum siding for any signs of damage, mildew, or chalking–powdery paint pigment.

• Look for dents, scratches, or loose panels that may need repair
• Check for areas of mildew, which appear as dark spots or streaks
• Test for chalking by rubbing the surface with a dark cloth
• Cover nearby bushes and ground with drop cloths

If you notice any of these issues, address them before painting. Repairing damaged areas and treating mildew will ensure a better paint finish and longer-lasting results.

Gather Materials

To paint aluminum siding, you’ll need the following tools and materials:

• Acrylic primer specifically designed for metal surfaces
• High-quality acrylic exterior paint
• Paint brushes and rollers
• Drop cloths or plastic sheeting
• Chlorine bleach, trisodium phosphate (TSP), and water
• Pressure washer or abrasive sponges
• Ladder
• Disposable gloves and safety goggles

Pro tip: When selecting brushes for exterior aluminum siding, a 3-inch straight-edge siding brush handles broad surfaces, while a 2-inch angled sash brush works best for cutting in around windows and trim. For latex exterior paints, choose nylon or polyester bristles rather than natural bristles, which can absorb water from latex paint and ruin the brush.

Test for Lead Paint

Before you begin any work on older siding, you must test for the presence of lead paint. “Anything before 1978, we’re going to have to test for lead paint,” says This Old House painting expert Mauro Henrique. He recommends keeping a lead test kit on hand before starting any prep work on older homes, as it’s the essential first step before removing paint on an older home. Using a simple lead test kit can identify this hazardous substance. If lead is present, contact a licensed lead abatement specialist before proceeding with your project.

Safety Precautions

Working with chemicals can be hazardous, so follow proper safety guidelines. Always wear protective clothing, including gloves and goggles. Use a mask to avoid inhaling dust and fumes, especially when sanding. Make sure your workspace is well-ventilated.

Cleaning Aluminum Siding

Depending on the size of your project and the tools available, you can use several methods to clean aluminum siding.

Create a Cleaning Solution

To clean your aluminum siding effectively, mix the following in a bucket:

• 1 cup chlorine bleach
• 1 cup TSP
• 1 gallon of water

Wear gloves and safety goggles when handling this solution, as it contains strong chemicals.

Manual Cleaning Method

For smaller areas or if you prefer a more hands-on approach:

1. Dip an abrasive sponge into the cleaning solution
2. Scrub the siding in a circular motion, working from bottom to top
3. Rinse the cleaned area thoroughly with a garden hose
4. Repeat the process until all siding is clean

Pressure Washer Method

For larger areas or to save time, a pressure washer can be an effective tool. Use the correct nozzle and angle the spray downward to avoid forcing water behind the siding:

1. Connect the pressure washer to a garden hose
2. Attach a fan-spray tip to the washer’s wand
3. Fill the washer’s reservoir with the cleaning solution
4. Start at the bottom of the siding and work your way up, spraying at a downward angle
5. Keep the spray nozzle moving to avoid damaging the siding
6. Rinse thoroughly with clean water, again working from bottom to top

Alternative Cleaning Methods

For stubborn areas or to remove old paint, consider a random-orbit sander. A sander provides thorough cleaning, which aids in achieving a smooth and tacky paint surface:

1. Attach the sander to a wet/dry vacuum equipped with a HEPA filter
2. Use a 100-grit abrasive disk on the sander
3. Gently sand the surface, being careful not to damage the siding
4. Vacuum up any dust or debris as you work

Dealing with Mildew

Mildew can be a persistent issue with aluminum siding. If you encounter mildew spots:

1. Apply a mildew-resistant cleaner to the affected areas
2. Scrub gently to remove the mildew
3. Rinse thoroughly to prevent recurrence

Prime and Paint the Aluminum Siding

You can begin the painting process once your siding is clean and dry.

Choose the Right Paint

Acrylic paint is the best choice for aluminum siding. It adheres well to metal surfaces and provides excellent durability. Choose a high-quality exterior acrylic paint in your desired color. Avoid oil-based paints, as they don’t perform as well on aluminum.

Prime the Surface

Applying a primer assists paint adhesion and longevity. Primer helps to create a uniform base for the paint, ensuring it adheres properly and lasts longer. Make sure to cover all areas evenly with these steps:

1. Select an acrylic primer specifically designed for metal surfaces
2. Apply the primer using a brush or roller, following the manufacturer’s instructions
3. Allow the primer to dry completely before painting

Painting Techniques

To achieve the best results when painting aluminum siding, remember to paint on a day with mild temperatures and low humidity for the best results. Extreme temperatures can affect paint adherence and drying time. Keep these techniques in mind:

1. Start at the top of the house and work your way down
2. Use a brush to cut in around windows, doors, and corners
3. Apply paint with a roller for larger areas, using long, smooth strokes
4. Apply two thin coats of paint rather than one thick coat
5. Allow adequate drying time between coats

Choose the Right Tools

Select high-quality brushes and rollers designed for exterior use. A wide brush can help cut around edges, and a roller can quickly cover larger surfaces.

How To Maintain Painted Aluminum Siding

To keep your newly painted aluminum siding looking its best:

• Wash the siding annually with a mild detergent solution
• Inspect for any chips or peeling paint and touch up as needed
• Trim bushes and trees away from the siding to prevent scratches
• Avoid using harsh chemicals that can strip away paint

Regular maintenance will help extend the life of your paint job and keep your home looking fresh.

Touching Up

Touch-ups might be necessary over time to maintain a pristine appearance. Keep some leftover paint for easy touch-ups.

Reapplying Paint

Depending on wear and tear, a fresh coat of paint every 5–10 years can keep your home looking newly painted. Regularly inspect your siding for signs of wear, such as fading or peeling, and address these issues promptly.