Composite decking refers to outdoor decks made from wood fibers (or dust) and recycled plastic. They are designed to mimic the traditional deck appearance but are reinforced with protective additives to make them durable and last longer.
To paint composite decking, clean the deck, sand the deck, apply primer, and apply paint.
Paints don’t adhere well to composite deck boards as the boards aren’t designed to accept paint and are reinforced with protective additives that prevent paint penetration. So, you must remove their protective outer layer before painting.
Do Paints Adhere to Trex or Composite Decking Boards?
Paints don’t adhere to trex and composite decking boards as the boards aren’t designed to accept paint and are usually dirty. But, if you sand, clean, and apply primer, paints will adhere to them.
Composite decks don’t accept paints as they are formulated with protective additives to protect them from weather elements and foot traffic. The protective additives form a moisture-resistant coating over the decks that prevents paints from penetrating or adhering.
Composite decks are placed outdoors and accumulate dust, dirt, and filth that can prevent paint penetration or adhesion.
What Paint Types To Use over Trex or Composite Decking?
Use oil-based paint, primer, and sealer over composite or Trex decking. Oil-based finishes are durable, and colorful, have a glossy finish, and protect the decks from moisture, water, and scratches.
To seal composite decking, use exterior polyurethane or varnish. Exterior sealers form a glossy moisture-resistant barrier over the paint finish and protect the underlying surface from moisture, water, and weather elements.
Don’t use unsealed water-based paint over outdoor composite decks as the paint isn’t durable or resistant to water, and won’t protect the surface from weather elements.
Water-based paints are water-soluble and will be removed if exposed to constant water. If you want to use water-based paint over outdoor decks, seal the finish with exterior polyurethane.
How To Paint Composite Decking?
To paint composite decking, do the following things.
- Clean the Deck.
- Sand the Deck.
- Apply Primer.
- Apply Paint.
The tools you need for this project are listed below.
- A garden hose
- A bottle of white vinegar
- A bristled brush
- A large drop sheet
- Water-based paint primer
- An exterior paint of your choice (for this guide, I’m using acrylic exterior paint)
- A spray gun
- Medium and fine-grit sandpaper.
1. Clean the Deck
Clean the deck to remove dust, dirt, or debris that can prevent the new paint from penetrating or adhering over it. If you don’t remove the dirt, paint won’t penetrate the surface nor adhere, creating a sticky finish.
To clean composite decking before painting, do the following things.
- Mix water and detergent in a bucket.
- Pour the mixed water over the deck surface.
- Use a bristled brush to scrub the dirt off the deck.
- Pour clean water to remove the detergent residue.
- Allow the deck to dry.
2. Sand the Deck
Sand the deck to remove the existing paint finish (if any), the surface imperfections and bumps, and create tiny pores (holes) that the new paint can penetrate and adhere to.
To sand composite decking before painting, do the following things.
- Use medium-grit sandpaper (100-grit). If the deck is large, use a power sander.
- Don’t apply pressure on the sandpaper while sanding.
- Finish sanding with fine-grit sandpaper (220-grit).
- Remove dust.
3. Apply Primer
A primer coating covers the deck surface imperfections and holes and creates a smooth layer for the new paint to adhere to. Ensure to use a primer that’s compatible with the new paint you want to apply.
To apply primer, do the following things.
- Apply one (1) thick primer coat or two (2) light coats.
- Use a roller or sprayer to apply it.
- Wait until one coat dries before applying the next one.
However, the primer covers the wood grain and prevents it from showing once the paint dries. So, applying primer is optional if you are planning on applying a transparent finish for the wood grain to show.
4. Apply Paint
Apply 2-3 paint coats over the trex deck surface using a paint sprayer, roller, or brush. It’s recommended to use oil-based paint for outdoor deck surfaces, and water-based paint for indoor surfaces.
The exact number of paint coats depends on whether you applied primer or not, and if the surface is already painted or not. The more paint coats the deck already has, the fewer new coats you must apply.
You must seal outdoor deck surfaces with an exterior wood sealer to protect them from weather elements. Sealing indoor decks is optional as the surface isn’t exposed to water.
Can You Change The Composite Decking Color?
You can change the composite deck color, but you must remove the deck’s protective outer layer. The protective outer layer prevents new paint from penetrating or adhering over the deck, so you must remove it if you want to paint over it.
Don’t try to change the fresh composite deck color as you can damage the deck, void the warranty, or create a sticky paint finish that won’t adhere. Fresh composite decks are factory-sealed with additives that prevent paint or stain, and you shouldn’t paint over them.
You can change the color of an old composite deck by sanding its protective outer layer with coarse-grit sandpaper, applying a primer coating, and then applying the new paint.
Which Composite Decks Types Can You Paint?
You can paint composite decks made from natural materials that don’t repel paint and uncapped decks that don’t have a protective layer that prevents paint adhesion.
You can’t paint capped composite decks made from synthetic materials as they are reinforced with an extra tough layer that makes them more durable and resistant to liquids.
If you apply paint over a capped composite deck, the paint won’t stick and will turn tacky as the extra tough layer prevents paint penetration.
How Often Should You Re-paint Composite Decking?
You should paint composite decking every 5 years after the first paint. Once you remove the deck protective layer and apply a new paint finish, the decks become less durable and the new paint gets removed faster.
Since the new paint finish isn’t as durable, you must touch up with a new paint and sealer coat every 5 years.
If the composite deck isn’t painted by you, you don’t need to re-paint it ever.
Staining vs. Painting (For Trex Decking)
Staining trex decking is better than painting them. Trex decks are highly porous and accept thick wood stain coatings better. If you apply paint directly over the deck, it will absorb too much paint, creating an uneven finish.
If you want to paint trex decking, apply a washcoat or primer coat to seal the deck pores and prevent over-absorption.
Painting trex decking is better than staining them if the deck is painted or sealed. Paint coatings adhere better to an existing finish while wood stains can’t penetrate or adhere if the surface is painted. You must remove the existing finish, and then apply the stain.