Painting Composite Deck or Trex (Can You Do it & How-To?)

Painting regular decks is easy, but can you paint composite decks or Trex?

You can paint or stain a composite deck if it’s made of wood fibers and plastic. Wood fibers and plastic are two ingredients used to make composite and Trex decking, so you can paint over them.

However, if they are made of different ingredients besides wood fibers and plastic, painting them is harder. That’s because you must clean, sand, and prime it first, and you must use paint (or stain) with weather-resistant qualities. 

Compatibility

Paint doesn’t stick well to Trex or composite decking for two reasons; they are not designed to accept it or have a dirty and dusted surface. However, if you sand, clean, and prime them, the paint can stick over them.

First, composite decks are not designed to be painted over because they are designed to hold the weight and foot traffic and resist weather elements. To do these tasks, they are sealed and reinforced with additives to improve their strength and make them waterproof.

They are also installed outdoors and around the entrance of the home, so they are filled with dust, dirt, and filth. Since they are filled with dirt, paint won’t stick over them if you don’t clear their surface.

Type of Paints To Use

What Type Of Paint To Use On Composite Deck?

It’s recommended to use an oil-based primer, paint, and sealed to finish a composite deck. Oil-based paints are durable, colorful, and have a glossy finish. Once you seal it, its finish becomes moisture, water, and scratch-resistant. You can also use composite deck paint.

To seal them, use exterior polyurethane or varnish. These two sealers will form a glossy thick layer over the surface and make it water, moisture, and damage resistant. The thick sealant layer also protects the finish from weather elements.

You shouldn’t use unsealed water-based paints over outdoor composite decking. That’s because they aren’t durable or resistant to water and moisture. The paint will get washed off if exposed to constant water. If you want to use water-based paint outdoors, you must seal it.

Paint lasts between 1-5 years on composite decking. On average, most paints last up to 3 years. Interior (or water-based paint) won’t last more than 1 year, while exterior (or oil-based) paint will last up to 5 years.

Staining vs Painting 

It’s better to stain than paint a Trex decking because its surface is absorbent and designed to accept stains. They are also porous, so the stain penetrates the surface and sticks well over them.

Since Trex is porous, applying paint over it is hard because its surface will suck too much paint, and the finish will be uneven. You must apply a stain-blocking primer to prevent over-absorption.

If the Trex decking is painted and sealed, you can’t stain over it. That’s because the existing paint and sealer prevent the stain from penetrating the surface. You must remove the existing finish first, and then apply the new coating.

How To Paint Composite Deck?

Painting composite decking is hard if you don’t have the right tools. Here are the tools you need:

  1. A garden hose
  2. Detergent
  3. A bottle of white vinegar
  4. A bristled brush
  5. A large drop sheet
  6. Water-based paint primer
  7. An exterior paint of your choice (for this guide, I’m using acrylic exterior paint)
  8. A spray gun
  9. Medium and fine-grit sandpaper.

1. Wash The Deck

Wash The Deck

First, prepare the work area. Remove all objects, furniture, and planks from the surface and put a large drop sheet around it.

Next, clean the composite deck as paint won’t stick to a dirty, dusted, or filthy surface.

To clean it:

  1. Mix detergent in a bucket of water. 
  2. Use a bristled brush and the detergent mixture to wash it.
  3. Scrub off stubborn stains and spots from the deck. 
  4. After washing, remove the detergent residue with clean water. 
  5. Let the deck dry.

2. Sand The Composite Deck

Sand The Composite Deck

Sanding will remove the existing paint (or stain) and imperfections from the surface.

To sand it:

  1. Start sanding with medium-grit sandpaper (150-grit). 
  2. If the deck is large, use a power sander instead of manually sanding. 
  3. While sanding, don’t apply pressure or work as it can damage the surface.
  4. Finish the sanding with fine-grit sandpaper (240-grit).
  5. Remove the dust.

3. Apply Primer

Apply Paint Primer

Once the composite deck is clean and sanded, apply primer. The primer must be compatible with the composite deck and the type of paint you will use. For instance, if you want to use oil-based paint, apply an oil-based primer.

To apply primer:

  1. Use a roller or sprayer for large surfaces and a brush for small surfaces.
  2. Apply 2 coats of primer.
  3. Wait until one coat dries before applying the next one. 

4. Apply The Paint

Apply The Paint

Once the primer dries, apply the paint. If the paint is too thick or you use a sprayer, you must thin it. To thin oil-based paint, use mineral spirits, and to thin water-based paint, use water.

To apply paint:

  1. Use a sprayer, roller, or brush. 
  2. Apply 3 coats of paint. 
  3. Wait until one coat dries before applying the next one. 
  4. Ensure to apply an even layer. 
  5. Allow the final coat to fully dry before sealing it.

Sealing an indoor composite deck is optional as its surface isn’t exposed to constant moisture. But, sealing an outdoor composite deck is necessary its surface must be durable enough to withstand weather elements.

To seal it, apply 2 coats of exterior polyurethane or varnish.

Changing the Color

Can I Change The Color Of My Composite Deck

You can change the color of your composite deck. It’s a great way to add value, beauty, and protection to it.

However, you shouldn’t paint over new or fresh composite decking. That’s because they are factory-sealed with additives that repel liquid, so they won’t accept paint. You must only paint or change an old composite decking color if its finish is old or washed off.

Though most manufacturers claim that its paint or color will last forever, it doesn’t. After some years, its finish will begin to discolor and fade away due to weather elements. At this stage, you can change its color or paint it. 

Types of Composite Decks

You can paint composite decks made from natural materials such as plastic and wood fibers as they don’t repel paint. Also, you can paint uncapped composite decks, too, because they don’t have a cover (or sealer) that prevents paint adhesion.

On the other hand, don’t paint over capped composite or decks made mostly of synthetic materials. That’s because they are sealed and reinforced with additives that make them resistant to moisture and liquid.

If you apply paint over a capped composite deck, the paint won’t stick and will turn tacky. To paint them, you must clean, sand, and prime them first.

Re-paint Every 1-3 Years

There is no specific time frame to paint composite decking. You must only paint or stain them when the existing finish starts to fade. The time it takes for the existing finish to fade depends on the type of deck, finish, and level of maintenance. On average, it takes up to 5 years.

Here are some cases where you’ll need to re-paint it:

  • You don’t like its finish (or color).
  • Its surface is damaged and has blotted spots.
  • Some parts of the composite decks vanish. 
  • If the surface is affected by water. 

Final Words

You can paint composite or Trex decking made of plastic and wood fibers. However, if the composite decking is made of too many synthetic materials and is sealed, you can’t paint over it.

To paint over a sealed composite decking, remove the existing finish, sand the surface, and then apply a primer and paint. On the other hand, Trex decking is porous, so you must apply a stain-blocking primer before applying the paint.

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