While painting treated wood may not be the ideal finish for this type of lumber–stains and sealers are a much better option–there are certain looks that can only be attained with a good coat of paint. A white picket fence or slate gray deck, for example, can add a striking look to a home.
You can paint pressure-treated wood after the wood has sufficiently dried out by using a high-quality exterior primer and paint. That said, it’s important to understand that a paint job on treated lumber won’t last as long as a paint job on untreated lumber.
This article will discuss strategies for painting pressure-treated lumber and provide step-by-step instructions for getting the job done.
- Can you Paint Pressure-Treated Wood?
- How Do Different Types of Treated Wood Affect Painting
- Is It Better to Paint or Stain Pressure-Treated Wood?
- Should You Paint Pressure-Treated Wood?
- When Can You Paint Pressure Treated Wood?
- How To Prepare Treated Wood for Painting
- Painting Pressure Treated Wood: Step by Step
- How Long Should You Wait to Paint Treated Wood?
- Best Paint for Pressure-Treated Wood
- Best Primer for Pressure-Treated Wood
Can you Paint Pressure-Treated Wood?
Pressure-treated wood isn’t as easy to paint as untreated lumber, but it is possible to paint it successfully. Pressure-treated lumber is saturated with chemicals designed to resist rot and bug infestation. These same chemicals make it difficult for the paint to adhere to the wood.
Before painting pressure-treated wood, make sure the wood is properly dried out, which we will discuss in detail below.
Pressure-treated wood won’t soak up paint and untreated wood, so using a high-quality primer to help the paint adhere to the wood is crucial. Pressure-treated lumber is also traditionally used outdoors, such as a deck, fence, or treehouse. With that in mind, you’ll need to select a durable exterior paint that’s capable of holding up against the elements.
There are also different types of treated wood, which impacts what kind of paints and primers you can use.
How Do Different Types of Treated Wood Affect Painting
Though we rarely differentiate between the different types of pressure-treated wood when completing a fence or deck project, it’s important to understand how they can impact a painting project. How you prep and paint pressure-treated wood can vary depending on the type.
There are three main types of pressure-treated lumber– Copper Azole (C-A), alkaline copper quat (ACQ), and chromate copper arsenate (CCA). While C-A and ACQ don’t require special treatment when priming or painting, CCA, which is only found in older treated lumber, requires special care. CCA should be primed and painted with oil-based paint as water-based paints can damage the coating.
Is It Better to Paint or Stain Pressure-Treated Wood?
It is better to stain pressure-treated wood because a stain will produce better results and last longer than paint because it creates a stronger bond with the wood.
Even after pressure-treated wood has had ample time to dry, the chemicals used to treat the wood will hinder how well the paint bonds to the wood. As a result, the paint will peel and fade, requiring additional coatings every couple of years.
In comparison, stain soaks into the wood grains, creating a tighter bond than paint and, therefore, a longer-lasting finish that requires less maintenance. Stain can also be combined with a sealer to further preserve the finish.
Should You Paint Pressure-Treated Wood?
The only reason you should paint pressure-treated wood is for aesthetic purposes, as a coat of paint will not provide any added protection against the elements.
Even after allowing pressure-treated lumber to dry and using a quality primer, paint jobs on decks typically do not last long, often requiring the homeowner to repaint the surface every couple of years.
If your goal is to provide a protective layer for a deck, bench, or fence, use a wood sealer instead. If you plan to paint pressure-treated wood, keep in mind that paint lasts longer on vertical surfaces, such as fences, than horizontal ones, such as decks.
When Can You Paint Pressure Treated Wood?
You can paint pressure-treated wood after it has had a chance to fully dry, a process that can take 3 to 4 months or more if you live in a humid region. There are ways to dry pressure-treated wood more quickly without warping it in the process, but these options usually aren’t available to the average homeowner.
One solution is to use a wood kiln or dehumidifying kiln if you happen to have access to one. These kilns will dry out wood quickly and are what lumber companies use to produce kiln-dried lumber.
Another option is to stack the pressure-treated wood in a criss-cross pattern in a climate-controlled space. Using this method, you can lower the humidity in the space using a dehumidifier, drying out the wood over a period of days.
Resist the urge to paint pressure-treated wood before it fully dries. The moisture content in green pressure-treated wood can be as high as 75 percent.
That means there’s very little available space inside the wood fibers to soak up paint. Painting green pressure-treated lumber will likely result in an uneven finish and peeling paint.
How To Prepare Treated Wood for Painting
Let the Wood Dry
It’s important to properly prep pressure-treated wood before painting it to achieve the best results. As discussed above, green-treated lumber is saturated with the chemicals used to protect it from water and pests.
If you’re planning on painting a brand new deck or fence, you’ll need to wait as pressure-treated wood needs time to dry out before you paint it.
How long does it take? You’ll need to wait 3 to 4 months before pressure-treated lumber begins drying out.
Exactly how long it takes varies depending on the climate. Pressure-treated wood in arid regions will dry more quickly than wood in humid climates.
If you’re not sure if the wood is dry enough to paint, use the sprinkle test. Sprinkle water on top of the wood. If the water beads, it’s still too green to paint. You’ll also want to conduct this test on older wood if it’s recently rained.
If you attempt to paint pressure-treated wood before it dries out, it won’t accept the paint, resulting in a poor finish and a coating that will wear more quickly.
If you have a project that can’t wait, consider purchasing pressure-treated lumber that has been kiln-dried after being treated. Just keep in mind you’ll pay a premium for it.
If you’ve already bought the wood and aren’t sure if it is kiln dried, look for a stamp that says either ADAT (air-dried after treatment) or KDAT (kiln-dried after treatment).
Clean the Wood
Once the pressure-treated wood has dried out, clean it thoroughly. Use a soap and water solution and scrub the deck with a brush to loosen any dirt.
If the surface has excessive dirt and grime, use a pressure washer for a thorough cleaning. Allow the wood to dry for at least 24 hours before applying paint.
Do Not Sand the Wood
You’ll notice that sanding is not a step on this list. That’s because sanding pressure-treated lumber is a bad idea.
By sanding treated wood, you release the chemicals in the wood into the air, where you or bystanders can breathe them in.
Even while wearing a mask, exposure to these chemicals is potentially hazardous as some of these chemicals can potentially leach into your skin. Older CCA-treated lumber, for example, includes the poisonous chemical arsenic.
In addition to posing a health hazard, sanding treated lumber also partially removes the protective coating that serves as a weather barrier for the wood. While painting the deck will create a new barrier, it’s a good idea to have that additional protection below that thin coat to protect the wood when the paint wears out.
There’s also no real benefit to sanding treated wood, which should already be smooth to the touch from its weather-resistant coating.
Painting Pressure Treated Wood: Step by Step
Step 1: Apply a Coat of Primer
Once the wood has dried out enough to receive paint, it’s time to apply a coat of high-quality latex primer. Avoid using oil-based primer, which takes a long time to dry, allowing time for debris to fall onto the deck and stick to it. Make sure to use a primer that’s listed for use for treated and exterior wood. If you’re painting a deck, several companies, including Rustoleum and Kilz, make excellent primers specifically for decks.
When applying the primer, use a bristle brush instead of a sprayer to ensure an even coating and a good bond between the coating and the wood surface. Allow the primer to dry per the time listed on the label before proceeding with paint.
Step 2: Apply Paint
Use high-quality exterior latex paint to coat the deck thoroughly. You’ll want to apply two coats for full coverage and ensure a long-lasting finish. Make sure the first coat dries thoroughly before applying the next coat.
Keep in mind that it will take longer for the paint to dry on treated lumber even after it has had a chance to dry out.
Use a sprayer or a high-quality roller to apply paint to larger surfaces.
Step 3: Apply a Water Repellent Finish
Once you’ve applied two coats and they’ve dried thoroughly, apply a paint stabilizer that will protect the surface from ultraviolet rays that can cause the paint to fade while helping to prevent the paint from peeling.
How Long Should You Wait to Paint Treated Wood?
As we discussed above, how long you wait to paint treated wood largely depends on how new it is. If the wood is brand new, you’ll need to wait for 3 to 4 months unless the paint is kiln-dried. You can determine if the wood is air-dried or kiln-dried by finding the stamp on the side of the lumber.
If the treated wood is old, it’s ready for paint. Clean the wood using the steps above and allow it to dry before applying primer.
Best Paint for Pressure-Treated Wood
When selecting paint and primer for treated wood, make sure to purchase water-based coatings for the best result. While it is possible to spray paint treated lumber, you’ll achieve better results by using a high-quality bristle brush or roller. Below we review some of the best paints and primers for pressure-treated lumber.
Kilz Porch and Patio Floor PaintKilz Paint designed specifically for porches and patios is a great option for painting treated wood.
It uses a low lister finish that applies evenly, can endure the elements, and resists abrasions from foot traffic. It boasts excellent coverage and is more affordable than other options.
Kilz dries to the touch in about one hour and is ready for a second coat in 4 to 6 hours. The paint can be applied with a roller, synthetic brush or airless sprayer. One gallon covers up to 400 square feet on smooth surfaces.
INSL-X Tough Shield Floor and Patio PaintWith its numerous color options, this specially formulated paint for decks and patios is an ideal choice for treated lumber.
It consists of a water-based acrylic enamel resistant to water and oils. When dry, it produces a rugged satin finish with excellent abrasion resistance.
INSL-X comes in a variety of color options, making it an ideal choice for various projects. One gallon will cover up to 450 square feet. INSL-X can be applied with a large roller, making it ideal for bigger projects.
Best Primer for Pressure-Treated Wood
Kilz PremiumWith its ability to adhere to a broad range of surfaces, Kilz Premium is well-formulated for use on treated wood.
The primer is rated for outdoor use, making it ideal for fences and decking. It can withstand wet conditions and high humidity areas and has a thicker consistency that produces a smooth finish.
The primer also has mildewcide additives that prevent the growth of mold and mildew on surfaces. As with Kilz’s entire line of primers, Premium is also an excellent stain blocker and will mask imperfections, such as cracks and small holes, making it ideal for coating older pressure-treated wood.
Rust-Oleum Marine Wood and Fiberglass PrimerWith its weather-resistant qualities, Rust-Oleum primer designed for use on boats is an excellent option for priming treated lumber.
Many qualities that make it an attractive option for marine use apply to pressure-treated lumber.
This paint resists salt and moisture and has additives that prevent mold and mildew growth. It also contains UV inhibitors that help prevent fading from long exposure to the sun. Rust-Oleum Marine Wood and Fiberglass Primer comes in one-quart sizes and should be applied with a bristle brush.
While paint may not be the ideal coating for treated lumber, there are instances when it’s the preferred choice. Decks or fences with noticeable stains or projects that demand vibrant solid colors require paint.
By following the guidelines above, you can achieve the best possible results with your painting project. Just keep in mind that a painted fence or deck will only maintain its beauty for a few years before it will need touch ups or even a completely new paint job to refresh the look.