How To Prep for Exterior Painting

Your home’s exterior may need a fresh coat of paint occasionally, but before you grab your primer and brush, you must prepare your siding. This will help the new paint stay fresh and last longer. This guide will explain how to prep for exterior painting whether you have wood, aluminum, or vinyl siding. We’ve also included a video featuring This Old House host Kevin O’Connor and painting contractor Rich O’Neil, who share the steps you can take to get your home ready for a paint job.  

Benefits and Challenges of Exterior Painting Prep

Before we dive into the process, we’ll cover why you’ll want to prep your siding and what type of difficulties you might encounter. Some advantages of preparing your home’s exterior for a paint job include:  

• Improved paint adhesion
• Longer-lasting finish
• Opportunity to identify and repair damage
• Smoother, more professional appearance

An experienced DIYer can take on this type of project with the right tools, but they could still run into some issues. We’ve listed a few below:

• Addressing wood rot or damage
• Dealing with old, peeling paint
• Managing lead-based paint in older homes
• Working at heights safely

Tools You’ll Need for Exterior Painting

We recommend you collect everything you need beforehand so you don’t have to interrupt the process once you get started. The project will move faster and run smoothly if you have everything at your fingertips. Here are some of the items you’ll need:

• Caulk gun
• Chemical paint stripper (for intricate moldings)
• Dust mask and safety glasses
• HEPA filter vacuum
• Infrared paint stripper
• Molding scrapers
• Plastic tarps
• Pull-style paint scrapers
• Random orbit sander with 24-grit disks
• Scaffolding or sturdy ladders
• Staple gun

Pull-style paint scrapers come with different types of metal blades, such as steel or tungsten-carbide. We recommend using a tungsten-carbide blade because it stays sharper longer than other options, but steel is a good choice for budget-conscious DIYers.

Step-By-Step Guide to Exterior Painting Prep

Now that you have your tools, it’s time to get started. Take your time performing each task to get the best results. 

1. Set Up a Safe Work Area

In our video, O’Connor discusses why scaffolding is a safer option than a ladder when you have to prep the higher sections of your home. Whether you opt for scaffolding, here are some steps you can take to stay safe:

• Set up scaffolding or secure ladders
• Lay down drop cloths to protect landscaping
• Staple plastic tarps to the lowest course of the siding to catch paint chips

2. Remove Loose Paint

Once you’ve taken the proper safety precautions, you’ll have to remove loose and peeling paint to start smoothing the surface. Rich O’Neil demonstrates the proper technique for using pull-style scrapers if you’d like a visual, but here’s a quick breakdown of the steps you can take:

• Wear a dust mask and safety glasses
• Grab your pull-style scraper and start scraping
• Scrape side to side in the direction of the wood grain to prevent damage
• Remember to scrape the clapboards underside, which is the siding’s lower lip or butt edge 

3. Sand Remaining Paint

When you scrape the paint, you can remove looser pieces, but you’ll still have a lot more to get rid of. You can use an electric sander to smooth the surface by taking the steps below: 

• Attach a 24-grit disk to a random orbit sander
• Connect the sander to a HEPA filter vacuum to contain dust
• Keep the sander moving to avoid creating depressions in the siding
• Feather-sand the edges of stubborn paint down to bare wood

You can use the technique outlined above if you have to remove paint from the siding, but you’ll want to use a molding scraper when you have to get rid of the paint on molding. You can also use a heat source like an infrared paint stripper. It releases the adhesion between the wood and paint. To use this:

• Wear protective gear, such as goggles, a mask, and gloves
• Leave the infrared paint stripper on the spot for about a minute to soften the paint
• Scrape the paint off with your molding scraper before it cools
• Use a chemical stripper for intricate moldings and spots that are hard to reach

4. Address Nail Heads and Holes

Treating nails and holes the right way will prevent rust. It will also help you get a smooth finish. Follow our tips below if you encounter any nails:

• Caulk nail holes to prevent moisture penetration
• Sand rust from nail heads
• Set nails below the surface of the wood

Best Practices for Exterior Painting Prep

Preparing your home’s exterior for a new paint job is a complex DIY project, so we have some tips to share to help you along the way:

• Address any wood rot or damage before painting
• Allow adequate drying time if using chemical strippers or cleaning solutions
• Clean the surface thoroughly after prepping to remove dust and debris
• Prime bare wood areas before applying the final coat of paint
• Work in manageable sections to avoid overwhelming yourself

Painting Considerations for Different Siding Materials

In the video above, our experts work on a wood surface, but the preparation process may vary depending on your siding type. We’ll address those below: 

Wood Siding

Water can penetrate the wood and cause it to rot, which makes it harder for paint to adhere to the surface.

• Inspect for rot or damage and replace affected boards
• Fill small cracks or holes with wood filler
• Sand rough areas smooth

Vinyl Siding

Vinyl siding can collect dirt and debris you have to remove so that your paint doesn’t start to peel prematurely. 

• Clean thoroughly with a pressure washer or cleaning solution
• Check for loose or damaged panels and repair as needed
• Use a primer specifically designed for vinyl siding

Aluminum Siding

Your aluminum siding could have chalking and rust. Address those problems by taking the steps below: 

• Remove chalking with a power washer
• Sand any rusty areas and apply a rust-inhibiting primer
• Use a bonding primer to ensure good paint adhesion

Additional Painting Tips and Techniques

We’ve already covered a lot, but we have more tips and techniques to help you achieve the best results. These smaller details can make painting your home easier.

Dealing with Mold and Mildew

Most of us understand the need to address mold and mildew inside the home, but they can also cause health problems on your home’s exterior. Take these steps to treat them:  

• Clean affected areas with a mixture of water and bleach
• Scrub the area with a brush and rinse thoroughly
• Allow the area to dry completely before continuing

Priming Bare Wood

Once you’ve removed all the paint from your siding and addressed any issues that may have popped up, you can prime it for a more durable finish.

• Use a high-quality exterior primer
• Apply primer with a brush or roller
• Allow primer to dry according to manufacturer’s instructions

Check the Weather 

The wrong weather conditions can make any painting project quickly turn south. 

• Check weather forecast before starting the prep process
• Avoid working in direct sunlight or high humidity
• Be mindful of wind conditions that can affect debris and drying times

Dispose of the Waste 

You need to get rid of paint chips and debris properly, especially if you’re dealing with lead paint. 

• Be cautious of lead-based paint in homes built before 1978
• Hire a disposal service for large projects
• Follow local regulations for disposal of hazardous materials
• Use heavy-duty plastic bags to collect debris

Steps for prepping an exterior for paint

1. Set up scaffolding for easy access to the house wall.
2. Staple a plastic tarp to the lowest course of siding to catch paint chips.
3. Don dust mask and safety glasses, then use a pull-style paint scraper to scrape loose paint from the siding. Tungsten-carbide-blade scrapers stay sharper longer, but steel-blade scrapers are cheaper and can easily be re-sharpened with a file.
4. Always scrape in the direction of the wood grain to prevent damaging the siding.
5. Remember to scrape paint from the lower lip (butt edge) of the siding, too.
6. Remove any remaining paint with an electric random-orbit sander fitted with 24-grit disk. Connect the sander to a vacuum equipped with a HEPA filter.
7. Keep the sander moving at all times to avoid sanding a depression into the siding.
8. Feather-sand the edges of sound, well-adhered paint down to bare wood.
9. Sand rust from nail heads, then set and caulk the nail holes.
10. Use a molding scraper to remove paint from convex shapes.
11. Chemical strippers can be used to loosen paint from intricate moldings.
12. An electric infrared paint stripper uses heat to release the paint’s adhesion to the siding.
13. Hold the infrared stripper in place for one minute, then immediately scrape off the softened paint.

Our Conclusion

Prepping your home’s exterior before you start painting will pay off with a more professional-looking and longer-lasting paint job. This is a complex DIY project that requires experience. If you aren’t comfortable using scaffolding or ladders or want to avoid strenuous activity, hire a professional painter to handle the job. 

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