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Recycled plastic lumber is popping up all over in decks and outdoor construction. Folks keep wondering if it’s tough enough for real structural parts—joists, beams, that kind of thing—or if it’s just meant for trim. Yes, recycled plastic lumber can sometimes work for structural components, but there are a few things you’ll want to check before diving in.
The rules are a bit different from regular wood, and not every recycled plastic product acts the same. Staying safe and following code? That’s always the goal. Let’s dig into what makes this material tick, where it shines, and where it falls short.
Key Takeaways
- Recycled plastic lumber has its strengths and weak spots for structural use.
- Building codes and approvals really matter here.
- Picking the right product and installing it right makes all the difference for deck safety.
What Is Recycled Plastic Lumber?
Recycled plastic lumber is made from old plastic waste—think bottles, packaging, and the like. It’s designed to look and feel a bit like wood, but it shrugs off rot and bugs, which makes it a practical choice for lots of outdoor jobs.
How Recycled Plastic Lumber Is Manufactured
It all starts with collecting things like milk jugs and detergent bottles. Companies clean and shred them into little flakes, then melt those down and press them into planks or boards.
Some brands stick to pure plastic, while others blend in wood fibres for extra strength or a more wood-like look. The boards get shaped, cooled, and sometimes textured to fake a wood grain. The result? Lumber that stays nice and straight, with way less chance of splintering.
Types Of Recycled Plastic Lumber
We usually see two main types:
- 100% plastic lumber: This is all recycled plastic. It’s heavy, super tough, and doesn’t care about water—great for benches or posts where you need durability above all.
- Composite plastic lumber: Here, plastic gets mixed with wood fibres (or minerals). It looks a bit more like real wood and is easier to cut or drill with regular tools.
Quick rundown:
| Type | Made From | Strength | Looks Like Wood | Common Use |
|---|---|---|---|---|
| 100% Recycled Plastic | Plastics only | High | No | Benches, posts |
| Plastic-Wood Composite | Plastics + wood | Medium/High | Yes | Deck boards, railing |
Which one to pick? Depends on your project. Want that cedar look? Go composite. Need something that shrugs off everything? Pure plastic is your friend.
Common Uses In Construction
You’ll find recycled plastic lumber in decks, docks, fences, picnic tables, playgrounds, and all sorts of outdoor furniture. It’s even showing up in posts and beams for smaller builds.
It’s a champ in wet spots—pool decks, docks—because it won’t rot or swell. Bugs ignore it. Gardeners like it for raised beds since it doesn’t leach chemicals.
For deck projects, plastic lumber means less maintenance and fewer repairs down the road. If you’re tired of sanding and sealing every year, this material starts to look pretty appealing.
Structural Properties Of Recycled Plastic Lumber
Recycled plastic lumber comes from old plastics—milk jugs, detergent bottles, that sort of thing—melted and shaped into boards. It’s got some quirks compared to wood, especially when you use it for outdoor structures.
Strength And Load-Bearing Capacity
First thing you’ll notice: recycled plastic lumber isn’t as stiff as wood. It can hold a good amount of weight, but it tends to flex more under a load. The bending strength is usually 30-50% less than pressure-treated wood.
We end up spacing supports closer together—24 inches on centre, sometimes less—to avoid sagging. For deck surfaces, it’s fine. But for main supports, we often stick with something stronger.
Temperature matters, too. Plastic lumber softens a bit in the heat and can get brittle in deep cold. If you’re thinking about using it for key framing, keep that in mind.
Durability And Weather Resistance
Plastic lumber shrugs off the weather. It doesn’t rot, warp, or splinter like wood—even in our soggy or snowy climates. The moisture resistance is a huge plus. Water just can’t get in, so no swelling or shrinking as the seasons change.
Most brands add UV stabilizers, so the boards hold their colour pretty well and don’t fade much. Maintenance? Just give it a wash now and then. No sanding or sealing required. If you’re after a no-fuss deck, this stuff is hard to beat.
Comparison With Traditional Wood
Compared to wood, plastic lumber behaves differently. It can’t match the raw strength or stiffness of something like Douglas fir or southern pine. It’s lighter, which makes it easier to move around, but you’ll probably need extra supports.
Here’s a side-by-side:
| Property | Recycled Plastic Lumber | Pressure-Treated Wood |
|---|---|---|
| Flexibility | More flexible | More rigid |
| Rot Resistance | Does not rot | Can rot over time |
| Maintenance | Low | Moderate |
| Workability | Cuts easy, nails less so | Saw and nail-friendly |
We often mix it up—plastic for surfaces, wood for framing. Visually, plastic lumber doesn’t have that real wood grain, but some brands get close with textured finishes.
Fire And Pest Resistance
Termites and carpenter ants? Not interested in plastic lumber. That’s a relief if you’re building in damp or wooded spots.
Fire’s a different story. Most plastic lumber is actually less fire-resistant than wood that’s been treated. It can melt and drip in a fire, while wood will just char. Some brands offer fire-rated options, but you’ll want to check the paperwork if fire safety is a big deal for your project.
For backyard decks, being bug-proof is a major win. For anything indoors or fire-sensitive, it’s worth a longer conversation.
Building Codes And Approvals
If you’re thinking about recycled plastic lumber for your deck or another structure, the big question is whether it meets code—and what the permit process is like. Canadian standards aren’t always straightforward, and inspectors will want details.
Canadian Standards For Plastic Lumber
Canada’s got rules. Recycled plastic lumber needs to pass certain standards before you can use it structurally. The Canadian Standards Association (CSA) has guidelines for wood (CSA O86), but plastic lumber follows different certifications—like ASTM D6109 or CSA S807.
These standards check that plastic lumber is safe and strong enough for beams, joists, or posts. As of now, most types are only approved for lighter jobs—decking, trim, railings. A few products have extra strength certifications, but it really depends on the manufacturer.
You’ll want to read the product labels and technical sheets before you start. Ask if the stuff’s been tested for structural use. If not, it probably won’t fly for main supports or frames.
Permitting And Inspection Considerations
When you submit plans for a deck, the city will look at your materials list. If you’re using plastic lumber for a structural part, inspectors need proof it meets code. Usually, that means showing off certifications or test results.
Most Canadian towns are careful with new materials, so you might have to provide extra info—or even get an engineer’s stamp. If you’re just using plastic lumber for deck boards or fascia, it’s usually simpler.
If you’re considering plastic lumber for structural parts, check with your local permit office first. Suppliers can help with the latest certifications. Saves time and headaches down the road.
Structural Applications For Decks
Recycled plastic lumber fits a bunch of deck jobs. Some spots are perfect, others—not so much.
Support Posts And Beams
Support posts and beams hold everything up, so they need to be solid. Plastic lumber won’t rot, splinter, or attract bugs. That’s great for wet or humid locations. But it isn’t as stiff as wood or steel, so it might flex more under load.
Building codes usually only allow plastic lumber posts and beams if the manufacturer lists structural ratings. We stick to rated products for major supports. Sometimes, we’ll use composite or plastic-wrapped wood for main beams and save pure plastic for smaller spans.
- Pros: Won’t rot or attract pests
- Cons: Less stiff, may need extra bracing
- Best Use: Low decks, small spans, or extra-wet spots
Joists And Framing
Joists and framing hold up your deck boards. Plastic lumber does okay here, especially in wet areas or near the ground, but you’ll need to space the joists closer together. Plastic flexes more, so you might use a bit more material.
It’s a top pick for docks or poolside decks, where water and chemicals are everywhere. Use stainless or coated fasteners—some plastics don’t play nice with regular metal hardware. Always check the manufacturer’s span tables before building.
- Pros: Water- and rot-proof
- Cons: Not as strong over long spans, can cost more
- Best Use: Docks, pool decks, ground-level decks
Stairs And Railings
Stairs and railings have to be safe—no exceptions. Plastic lumber works well for railings since it won’t splinter and barely needs any maintenance. Most plastic railings get reinforced with metal or fibre rods for extra strength.
Stair stringers are trickier. Some recycled plastic lumber just isn’t stiff enough for steep stairs or long runs unless you add extra support. For low steps and handrails, though, it’s tough and keeps looking sharp.
Stairs and railings checklist:
- Use reinforced products for extra safety
- Double-check code requirements
- Go for anti-slip treads on stairs
- Stainless fasteners last longer
Benefits Of Using Recycled Plastic Lumber Structurally
Choosing recycled plastic lumber for structural work comes with some real perks. It lasts, it’s tough, and it’s a greener pick than a lot of traditional options.
Longevity And Low Maintenance
Recycled plastic lumber stands up to our rough Canadian weather—rain, snow, summer sun. It won’t crack, split, or warp like wood. No need to stain, seal, or paint every year.
If you’d rather not spend weekends on upkeep, this stuff is worth a look. Cleaning is as easy as a hose and a brush. Colour runs through the whole board, so scratches are barely noticeable.
Quick facts on maintenance:
- No sanding, stripping, or staining
- No yearly sealant needed
- Fights off fading and splintering
Bottom line? It keeps decks, docks, and fences looking sharp with a lot less hassle.
Sustainability And Environmental Impact
Using recycled plastic lumber helps keep plastic waste—like old water bottles and packaging—out of landfills. This material gives new life to plastics that would otherwise just sit there for centuries.
As builders, we like that making this lumber uses a lot less energy than producing new plastic or processing wood. By choosing it, we’re cutting down on carbon emissions and supporting a circular economy.
Sustainability benefits:
- Reduces landfill waste
- Helps lower greenhouse gas emissions
- Saves forests by reducing demand for virgin wood
It feels good to know we’re making a better choice for the environment and still getting strong, safe materials.
Resistance To Rot And Decay
Traditional wood eventually rots or gets eaten by insects—especially in damp spots, like around lakes or garden beds. Recycled plastic lumber doesn’t soak up moisture, so rot, mildew, and fungus just aren’t an issue.
We use it for ground contact—like fence posts or retaining walls—without worrying about early failure. Bugs don’t care for it either, since there’s nothing for them to munch on.
Advantages for durability:
- Immune to insect damage
- Won’t absorb water or swell
- Ideal for wet or harsh environments
Our projects last for decades, even in Canada’s unpredictable weather and tough ground.
Potential Limitations Of Recycled Plastic Lumber
Recycled plastic lumber can be a smart alternative for some projects, but it’s not perfect for every job. Cost, availability, and how it behaves can make a difference.
Cost Factors
Recycled plastic lumber usually costs more up front than regular wood or even some composite options. The higher price comes from manufacturing, materials, and shipping.
Sometimes the extra cost is worth it for durability and low maintenance, but if you’re on a tight budget, it’s a tough sell. Bulk pricing isn’t always a thing, especially at local suppliers, so small projects can feel the pinch.
Here’s a quick cost comparison for a basic deck board (per linear foot):
| Material | Average Price (CAD) |
|---|---|
| Pressure-treated wood | $1–$3 |
| Cedar | $3–$6 |
| Composite | $4–$7 |
| Recycled plastic lumber | $7–$11 |
Installation can cost more too, since you might need extra fasteners or support for stability.
Availability And Sizing
Getting recycled plastic lumber in Canada isn’t as easy as grabbing a few boards at any hardware store. Options are pretty limited in some areas, especially outside big cities. Usually, we have to order from specialty suppliers, which means extra shipping time and cost.
Standard lumber sizes aren’t always available in recycled plastic. Some thicknesses, widths, or lengths just don’t exist, so it can be tricky for bigger builds or projects needing longer spans.
If your design calls for something unusual, you might need a custom order. That adds cost and delay. We often plan around what’s actually in stock, which means less flexibility than with wood.
Thermal Expansion Concerns
Plastic acts differently from wood. On hot days, recycled plastic lumber expands more than wood. When it cools, it shrinks back. In Canada’s wild climate, this can be pretty obvious.
Spacing and fasteners matter a lot. Without the right gaps between boards, decks can warp or buckle as the plastic swells. We always check manufacturer specs for proper spacing.
Extra movement can cause squeaky boards or loose fasteners. In strong sun or heat, you might see boards bow a bit or gaps pop up. We plan for this, especially for decks in full sun or big, open areas.
Best Practices For Installation
We want your recycled plastic lumber to perform and last. Here are some simple but important tips to follow during installation.
Fastening Methods
Plastic lumber flexes more than wood, so we use strong, corrosion-resistant fasteners. Stainless steel or coated deck screws are our go-to, since regular steel rusts, especially near water.
We pre-drill pilot holes before driving in screws. This keeps the material from cracking and gives a cleaner finish. We also leave a little space between boards (about 1/8 inch for most brands) to let them expand and contract with temperature swings.
Fastening through the face of the board is most secure. Hidden fastener systems usually don’t work well with plastic lumber, since it can be softer than wood and movement may loosen clips over time.
Cutting And Drilling Techniques
We cut recycled plastic lumber with standard woodworking tools—circular saws, miter saws, that sort of thing. Sharp carbide-tipped blades give smooth, clean edges. We cut slowly to avoid heat buildup, since too much heat can melt or gum up the plastic.
When drilling, slow speed is key. High speed makes the plastic heat up and clog the bit. Always clear shavings and keep the drill bit sharp.
Plastic lumber doesn’t splinter like wood, but it can scratch. We lay down mats or use soft supports under the boards while cutting and drilling to keep the surface looking good.
Choosing The Right Materials For Your Deck
When we build a deck, picking the right materials is huge. We want stuff that stands up to Canadian weather, resists rot, and needs little upkeep.
Here are some materials we use for decks:
| Material | Pros | Cons |
|---|---|---|
| Pressure-Treated Wood | Affordable, easy to find | Needs sealing, can split |
| Cedar & Redwood | Natural look, resists rot | Costs more, can weather |
| Composite Lumber | Low maintenance, long life | Higher up-front cost |
| Recycled Plastic Lumber | Resists rot, needs little care | Not as strong—best for decking, not structure |
With recycled plastic lumber, it’s great for deck surfaces, rails, and trim. It’s made from old plastics, so it’s more eco-friendly. But it doesn’t have the same strength as wood or composite for key support beams or joists.
We use treated wood or engineered materials for the deck’s frame. That gives us the strength to keep your deck safe.
Weather is a big deal too. In Canada, decks have to handle snow, rain, and sun. Some materials hold up better than others.
If you’re not sure what to pick, we’re always happy to chat and help you find what fits your style, budget, and how you plan to use your new deck.
Frequently Asked Questions
Recycled plastic lumber is getting attention in construction, especially for projects near water or in tough weather. Lots of folks ask about its suitability for structural work, code rules, performance, and long-term value.
What considerations should I be aware of when using recycled plastic lumber for load-bearing structures?
We always check the load ratings. Not all recycled plastic lumber is made for structural or load-bearing use.
Look for products that are certified and meet Canadian building standards. Temperature swings and sunlight affect plastic lumber more than wood, so we factor in movement and expansion.
How do the strength and durability of recycled plastic lumber compare to traditional wood for framing?
Recycled plastic lumber is water-resistant and doesn’t rot like wood. That’s a huge win in damp spots.
But its strength doesn’t always stack up for big framing jobs. It’s generally heavier and can bend more than wood under load, so it’s better for smaller spans or non-structural stuff.
Are there specific code requirements for implementing plastic beams in construction?
Codes depend on where you live, but we always follow local rules. Most building codes require structural products—including plastic lumber and beams—to have tested ratings.
We often need engineering approval or extra paperwork to use plastic beams for main framing. Always check with your city before starting.
Could you enlighten me on the drawbacks of employing plastic lumber for outdoor structures?
Plastic lumber can cost more up front than wood. It may also sag if not properly supported.
Some products get slippery when wet and heat up fast in full sun. If we skip proper installation—like not leaving space for expansion—boards might warp or buckle.
What variety of structural composite lumber is available, and how do they perform for different projects?
There’s a range, from plastic-only boards to mixes with wood fibre or fibreglass.
Lumber with fibreglass or other reinforcements tends to hold its shape better and works for bigger spans. We recommend picking the right type based on the strength you need and the look you want.
Can you shed some light on the applications plastic lumber is suited for, especially in decking?
Plastic lumber works really well for decks, docks, boardwalks, and railings. People tend to choose it in spots where regular wood just can’t hold up—think moisture, insects, or salty air.
I’ve seen it used a ton for decking because you barely have to maintain it, and it just keeps going year after year. Some of the newer stuff even pulls off a pretty convincing wood look, and hey, no splinters.