Composite decking is made of wood fibers combined with plastic, typically polyethylene or PVC, formed into boards.
Composite decking blends ground-up wood with plastic into manufactured planks designed to look like timber without the upkeep. Most boards pair reclaimed sawdust or wood flour with a polymer binder, then get shaped through extrusion. Some add a protective cap for extra moisture resistance.
The Core Ingredients In Composite Deck Boards
The base recipe for composite decking is simple: wood particles plus plastic, mixed with additives and formed into boards. The wood component is usually sawdust, wood flour, or reclaimed fibers. The plastic is commonly polyethylene (PE), polypropylene (PP), or PVC, depending on the product line.
Manufacturers blend these with bonding agents, color pigments, UV stabilizers, and mold inhibitors. The mixture is then extruded into deck boards. Capped products get an extra outer shell—called a capstock—that wraps the core for better protection.
One distinction matters: some “composite” decking is capped composite, meaning a wood-plastic core under a synthetic shell. PVC decking contains no wood at all and is technically not composite, though it often shares shelf space with composite lines.
What Manufacturers Actually Use
Real-world formulas vary widely by brand. Trex states its decking is made in the U.S.A. using 95% recycled plastic film and reclaimed sawdust. TimberTech says its composite boards use real wood fibers with high-performance polymers, with roughly 80% recycled content in capped composite lines. Other brands like Cladco and Ecoscape report mixes of recycled hardwood fibers, post-consumer polyethylene, and additives, with recycled content ranging from around 45% to 55% depending on the product.
Watch for variation rather than assuming one standard recipe. Some boards use virgin polymers instead of recycled plastic. Others swap wood for rice hulls, bamboo, or mineral fillers. The blend affects durability, color retention, and price, so check the spec sheet before buying. If you’re comparing options for a project, our roundup of the best composite decking breaks down top choices side by side.
How Composite Decking Is Made
Production starts with mixing wood fibers and plastic granules with additives. The blend is heated and extruded through a die to form boards. Capped products go through a second step where the capstock is bonded to the core, creating a sealed outer layer.
The extrusion process is what gives composite boards their uniform shape and consistent density—something natural wood can’t match. It also allows manufacturers to embed color throughout the board rather than just on the surface.
| Component | Typical Material | Purpose |
|---|---|---|
| Wood fiber | Sawdust, wood flour, reclaimed fibers | Provides bulk and a wood-like look |
| Plastic binder | PE, PP, or PVC | Holds the board together, resists moisture |
| UV stabilizers | Chemical additives | Prevents sun damage and fading |
| Color pigments | Tints and dyes | Matches wood tones |
| Mold inhibitors | Anti-fungal agents | Prevents mildew growth |
| Capstock (capped only) | Synthetic polymer shell | Adds moisture and stain resistance |
How Composite Decking Compares To Real Wood
Consumer Reports describes composite decking as an “amalgam of ground-up wood and plastic formed into planks” that never needs sealing, staining, or painting. That is the main draw: install it once and skip the yearly maintenance a timber deck demands.
Composite handles moisture and rotting far better than wood because the plastic matrix prevents water absorption. It also resists splintering and insect damage. The tradeoffs are higher upfront cost and a surface that can get hotter in direct sun than natural wood.
Not every composite is the same, so check three things before purchasing: whether the board is 3-sided or 4-sided capped, whether the product is composite, capped composite, or PVC, and what recycled percentage the manufacturer claims. The cap construction affects moisture resistance, and the material category changes how the boards behave over time.
Installation also depends on the exact board. Fastening, gapping, and cutting instructions differ by line and warranty, so always follow the manufacturer’s guide for your specific product type rather than assuming a universal approach.
FAQs
Does composite decking contain real wood?
Yes, most composite decking contains real wood fibers or sawdust mixed with plastic. The wood gives the boards their natural appearance, while the plastic provides durability and moisture resistance. Some products labeled as PVC decking contain no wood and are technically not composite.
Why does composite decking cost more than wood?
The manufacturing process drives the price. Mixing, extruding, and capping boards requires more equipment and energy than milling lumber. The materials themselves also cost more, especially when recycled plastic and polymer additives are involved. The higher price buys decades of low-maintenance service.
Can composite decking be painted or stained?
Most composite decking is not designed to be painted or stained. The color is embedded during manufacturing, so applying paint or stain will typically peel or fade unevenly. If you want a different color, choose a board with the shade you want rather than planning to refinish it later.
References & Sources
- TimberTech. “The Anatomy of Composite Deck Boards.” Explains the core ingredients and capped construction of composite boards.
- Consumer Reports. “Best Composite Decking From Consumer Reports’ Tests.” Describes composite as a wood-plastic amalgam that requires no sealing or staining.
- Wikipedia. “Composite Lumber.” Outlines the general composition and manufacturing process of wood-plastic composites.