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Recycled Wood/Plastic Composite Lumber

Mix of wood fibers and waste plastics turns into durable material

A deck made from recycled wood/plastic composite lumber.

Recycled wood/plastic composite lumber is one of the prime uses for recycled plastic trash bags and waste wood fibers. The composite material is used to produce building products such as decking, door and window frames, and exterior moldings. Manufacturers claim that products produced with recycled wood/plastic lumber are more durable than conventional preservative-treated lumber. Also, these products contain no toxic chemicals such as those used in conventional treated lumber.

Recycled wood/plastic composite lumber typically consists of a 50/50 mix of wood fibers from recovered saw dust and waste plastics that include high-density polyethylene, PVC, and others. The material is formed into both solid and hollow profiles.

Recycled wood/plastic composites are typically more rigid than 100 percent recycled plastic lumber because the wood fibers act as reinforcement. In addition, the plastic encapsulates and binds the wood together to resist moisture penetration and degradation from fungal rot.

Some recycled wood/plastic lumber products can weigh considerably more than standard lumber products. Like other plastic products, recycled wood/plastic lumber can become more flexible in hot weather and more rigid in cold weather than other decking materials.


Environmental Performance

By eliminating or reducing the amount of virgin materials used in production, and by making use of existing materials in its manufacture, recycled wood/plastic composite lumber contributes to the efficient use of resources. In addition, the lumber is not impregnated with chemicals in the manner of preservatively-treated lumber.

Quality and Durability

The lumber resists decay, does not splinter, and is straight. Compared to plastic lumber, it is more resistant to warping.


Easy

Depending on manufacturer, recycled wood/plastics can be purchased through building supply retailers throughout the country or direct from the manufacturer.


In general, recycled wood/plastic composites are cost-competitive with high-end decking materials such as finger jointed pine and redwood, but are significantly more expensive than standard treated products. Retail costs for 2 x 6-inch material are approximately $2.00 per linear foot.


As there is no need for painting or sealing, and given the material's durability, composite lumber products cost less to maintain than wood decks, railings, and fences.


Manufacturers of recycled wood/plastic composites typically have model code evaluation reports for their products to facilitate their acceptance in individual building jurisdictions.


Model reMODEL: Philadelphia, Pennsylvania


Recycled wood/plastic composites are commonly used to replace dimensional lumber in exterior decking and moldings, doorjambs, playground equipment, fencing, and other applications where durability is an important performance attribute. The material can typically be worked and installed using common carpentry tools. Both screws and nails with a hot-dipped galvanized coating are acceptable fasteners. Because there is no grain, pre-drilling is typically not required for self-drilling screws. Pneumatic nailers also work exceptionally well. A circular saw equipped with a carbide blade (preferably with a thin kerf and heat vents) provide very clean cuts. When installed as decking material, wood/plastic composite board should be spaced a minimum of 1/8" apart.

Once installed, recycled wood/plastic composite lumber may be left in its natural color or painted/stained after installation.


Warranties for composite lumber vary by manufacturer and product. They typically last 10 to 20 years, while some manufacturers offer lifetime warranties. Railing and fencing products are more likely to have longer lasting warranties than composite lumber decks.


Wood/plastic composites generally exhibit low moisture absorption and high resistance to decay, insect, and UV ray damage. As a decking material, wood/plastic composite material is said to require less maintenance than traditional lumber decking materials. It can be strong enough for applications such as load bearing deck boards. Wood/composite lumber tends to have significantly greater dimensional stability and a lower coefficient of expansion than solid plastics. Some composites use nearly 100 percent recycled raw material content. In general, recycled wood/plastic composites are cost-competitive with high-end decking materials such as finger jointed pine and redwood, but are significantly more expensive than standard treated products. Retail costs for 2 x 6-inch material are approximately $2.00 per linear foot.

Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the NAHB Research Center. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.