Is plastic wood easy to work with?

Plastic wood, also known as plastic lumber or composite lumber, refers to a material made of recycled plastic combined with other additives and filler materials to create a durable, weather-resistant building material that can be used as an alternative to traditional wood. With growing environmental concerns around deforestation and the sustainability of using real wood for construction projects, many builders and DIYers are exploring if plastic lumber can be an easy to work with and affordable substitute option. To understand if plastic wood is easy to work with compared to real wood, it’s helpful to look at some of the key factors like machining, fastening, finishing, weight, stability and overall workability.

Machining Plastic Wood

One of the most common tasks when working with any lumber is machining it to desired dimensions and shapes. This includes cutting, sawing, routing, drilling holes and other machining operations. Compared to natural solid wood, plastic lumber generally requires using carbide tipped blades and router bits. These help withstand the abrasiveness and increased friction heat that can be generated from machining thicker plastic wood boards. While sharp regular steel blades can be used for short runs, the carbide tips hold up better under extended use.

The machining process itself when working with plastic wood is relatively straightforward. It cuts, routs and drills similarly to wood. However, the synthetic material is more prone to melting from the heat of machining versus wood which produces more of a shaving type cut. Feeding the material slower through the blade or router bit prevents excess heat buildup. Additionally, holes may need to be drilled slightly undersized due to the material flexibility. Overall though, plastic lumber only requires some adjustments in blade type and feed rate to be machined into shapes and profiles with similar ease to natural wood.

Fastening and Joinery with Plastic Wood

Joining plastic lumber into structural projects or attaching surfaces and hardware requires fasteners and adhesives designed for its unique properties. Unlike the natural grain and pores in wood, plastic wood products are dense and impervious to water. This means traditional wood glues don’t bond well to the non-porous material. Epoxies, polyurethanes and some silicone or acrylic based adhesives make for the best glue choices. For fasteners, plastic lumber is flexible and will strip out threads easier than wood when over-torqued. Self-tapping screws designed for plastics work best. Pre-drilling pilot holes is highly recommended, usually 20% smaller than the screw diameter. Nails are generally not recommended except in applications dealing with very thin plastic wood boards. With the right adhesives and proper fastener selection, plastic lumber can be securely joined into projects.

Finishing and Painting Plastic Wood

One advantage of plastic lumber is that it does not require the same type of finish protection that wood needs against weathering and moisture. Plastic wood is highly resistant to cracking, rotting, splitting and decay. However, some plastic wood products come with a textured surface for resemble real wood, while others have a smooth surface. Adding colorant stains or paints is optional and comes down to the desired look. Paints and stains adhere well to plastic lumber with proper material preparation. Lightly sanding with 100-150 grit sandpaper creates surface profile for finishes to bond to. Then wipe clean with a degreasing solvent before painting. Both water and oil-based paints work well, providing long lasting color and protection from UV rays. The porous nature and tannins in wood can cause some finishes to fail prematurely. This is not a concern with plastic lumber’s closed cell structure, allowing it to hold up well to various painting and staining options.

Weight Differences of Plastic Wood vs Real Wood

An area where plastic lumber and natural wood differ significantly is in weight, which affects workability and handling. Dense hardwoods typically weigh 40-60 pounds per cubic foot. Softwoods are 25-35 pounds per cubic foot. Contrast this to plastic lumber which is around 20-35% of the weight of wood. For example, a 1×4 plastic board is about 1 to 1.5 pounds per linear foot. The same size solid wood board would be 3 to 5 pounds per linear foot. This lightweight nature of plastic wood provides several advantages:

• Easier lifting and maneuvering boards by hand
• Requires less structural support
• Puts less strain on fasteners
• Simplifies transporting and installation

The lower density also means plastic lumber lacks some of the strength characteristics of natural wood. Thicker dimensions and reinforcing inserts are used to overcome this. But the lightweight workability makes up for the tradeoff in many non-structural applications.

Dimensional Stability of Plastic vs Wood

Wood is prone to movement such as swelling, shrinking and twisting as moisture content changes in the environment. Plastic lumber maintains its original shape and dimensions much better than wood. There is very minor thermal expansion and contraction with temperature changes, but negligible moisture absorption issues. This stability means plastic wood stays straight, retains fasteners better, and does not warp or crack over time. It makes plastic lumber ideal for outdoor furniture, decking, trim and other projects where appearance and precision are important. The stability saves time trying to straighten, clamp or replace warped boards. Overall, plastic wood’s resistance to moisture and temperature fluctuation provides better long term dimensional stability than natural wood.

Workability and machinability comparison

When looking at all the factors of machining, weight, fastening and stability, here is a summary comparison between plastic wood and natural wood workability:

Property	Plastic Wood	Natural Wood
Machining	Requires carbide blades. Melts if overheated.	Uses standard blades well. Shaving cut.
Fastening	Use plastic specific screws. No nails.	Standard wood screws and nails.
Finishing	Paints and stains bond well without preparation. Withstands sun and weather.	Often requires sanding and pore filling for smooth finish. Requires refinishing over time.
Weight	20-50% the weight of wood. Easy to lift and work.	Heavier boards take more strength to maneuver.
Stability	Very stable. Won’t shrink, swell or twist.	Dimensional changes with moisture, swelling, cracks.

Overall, plastic lumber has some necessary adjustments when machining and fastening compared to natural wood. But its inherent stability and lightweight make it easy to handle, position and work for projects both large and small. With a few modifications to tools and techniques, plastic wood can deliver reliable results for the DIYer or professional.

Is plastic wood suitable for all construction applications?

While plastic lumber has some favorable working properties and environmental benefits, it does have some limitations on where it can be used structurally:

• Not recommended for load-bearing vertical columns or beams – lacks stiffness and strength
• Must be reinforced with aluminum or steel inserts in high stress/strain uses
• Not rated for horizontal floor joists, rafters or deck support framing
• Can be used for non-structural partitions, siding, trim, molding and decking
• Best suited for exterior aesthetic applications where weather-resistance and low maintenance are priorities

With lower mechanical properties than wood, plastic lumber is not a direct across-the-board substitute in all construction applications. It performs better in vertical applications like siding and trim than in horizontal load-bearing structural framing. The advantages lie more with stability, weathering and workability. For the right applications it can deliver an easy to work with alternative, but does have strength limits compared to natural wood.

Cost comparison of plastic vs natural wood

Upfront cost is often a factor when deciding on a building material. Plastic lumber typically ranges from 2 to 5 times the cost of pressure treated pine lumber. However, given its superior longevity and nearly maintenance-free performance, plastic wood becomes much more cost competitive over the lifetime of a project. Here is a comparison of approximate costs for common 1×4, 1×6 and 5/4×6 plastic wood boards vs traditional pine wood:

Board	Plastic Wood	Treated Pine
1×4	$4 lin.ft	$1 lin.ft
1×6	$7 lin.ft	$2 lin.ft
5/4×6	$9 lin.ft	$3 lin.ft

There is no denying plastic lumber planks can cost 200-300% more than pine. But factoring in plastic wood never needs sanding, sealing, staining or painting for its lifetime brings the true cost difference closer to 30-50% for highly durable exterior applications. The added benefits of sustainability from recycled plastic content and lighter weighting can offset some of the cost differential as well.

Conclusion

Plastic lumber brings some advantages of stability, weather-resistance, low maintenance and lightweight handling that provides an easier DIY experience compared to natural wood for certain applications. Aesthetically, plastic wood performs well in vertical siding, trim, molding and decking roles where appearance, durability and minimal upkeep are priorities. The workability is adequate with adjustments to blades, drill bits and fasteners. While plastic wood does not compete cost-wise or mechanically for all structural framing applications, where strength requirements are low to moderate, plastic lumber brings sustainability, longevity and ease of working benefits that make it a viable alternative to natural wood.