Composite vs PT vs cedar.
Real 20-year total cost of ownership for composite, pressure-treated, and cedar decking. Maintenance cycles, climate suitability, and when each material wins.
A deck is one of the few home projects where the up-front price and the true cost are almost unrelated. Pressure-treated pine is the cheapest thing to install, but it needs sealing every two years and usually wants replacing by year 15. Composite decking costs twice as much to install and then costs almost nothing for the next 25 years. Cedar sits in between and wins on pure aesthetics if you actually maintain it.
We ran the 20-year cost for a standard 320 square foot deck (16 × 20 feet, attached, one story). The answer surprised us.
How we calculated these numbers▾
Installed costs use mid-range 2026 pricing from HomeGuide, Angi, and Trex's published project costs. The 320 sq ft size represents a typical residential attached deck. Frame costs (joists, beams, posts) are constant across materials because the frame is pressure-treated regardless of surface. Sealing costs assume DIY material ($40–75 per application) plus labor time valued at $0 (DIY) or professional rates ($150–300 per visit). We used the professional rate as the baseline since most homeowners stop DIY-sealing after year 4.
That chart is the whole story. Pressure-treated is the most expensive material over 20 years. Not the cheapest. The most expensive. The sealing costs add up quietly, and the mid-life replacement hits hard. Cedar is actually the cheapest over 20 years if you stay on the sealing schedule. Composite is the middle option on pure cost, but it's the cheapest option when you account for your time.
Pressure-treated Southern yellow pine | Cedar Western red cedar | Composite Trex / TimberTech / Azek | |
|---|---|---|---|
| Material | $3–6 / ft² | $4–8 / ft² | $5–14 / ft² |
| Total installed | $25–50 / ft² | $30–47 / ft² | $40–80 / ft² |
| 320 ft² installed | $12,000 | $12,000 | $19,000 |
| Lifespan (surface) | 10–15 years | 15–25 years | 25–50 years |
| Seal frequency | Every 1–2 yr | Every 2–3 yr | None |
| 20-year total | $29,300 | $14,950 | $19,950 |
Installed costs at mid-range pricing. Frame is pressure-treated in all cases. PT total includes replacement of surface boards at year 15. Cedar assumes sealing maintained on schedule.
Pressure-treated: the cheapest start, the hardest commitment
Pressure-treated Southern yellow pine is the default. It's at every lumberyard, every Home Depot, and on every contractor's truck. The wood is infused with copper-based preservative (copper azole or MCA, not the old arsenic-based CCA that was discontinued for residential use in 2003) to resist rot and insects.
The material itself is fine. The problem is what it demands from you afterward. Fresh PT lumber ships wet. It has a greenish cast from the copper treatment. As it dries over the first 3 to 6 months, boards warp, twist, and cup. A good installer lets them acclimate before fastening. A cheap one screws them down off the truck and your deck has a rippled surface by fall.
Once it dries, you seal it. Then you seal it again in two years. And again. Skip a cycle and the wood checks, splits, and grays. Skip three cycles and boards are soft enough to punch through with a screwdriver. The sealing treadmill is why most pressure-treated decks look rough by year 8 and get torn off by year 15.
Cedar: beautiful if you do the work
Western red cedar is a naturally rot-resistant softwood. No chemical treatment, no green tint, no copper-fastener worries. It lies flat, stays straight, has a warm reddish-brown color that most people find prettier than PT or composite, and it weathers to a silver-gray if you leave it alone. Some people prefer the weathered look and skip sealing entirely. The wood survives; it just changes color.
Cedar's downside is softness. It dents easily. A dropped can of beer, a dog's claws, a dragged Adirondack chair. Every interaction leaves a mark. If your deck hosts kids, dogs, grills, and parties, cedar shows wear faster than anything else. That's the trade for the aesthetic.
Availability is regional. Cedar is cheap and everywhere in the Pacific Northwest where it's harvested. East of the Mississippi, it's a special order. In some Eastern markets cedar decking costs more than mid-range composite, which flips the 20-year TCO math.
Composite: the one that costs more and asks for less
Modern composite decking from Trex, TimberTech, and Azek is not the product it was in 2010. The early versions faded, stained, grew mold, and felt like plastic underfoot. Current capped composites have polymer shells that resist all of those things, come with 25-to-50-year fade and stain warranties, and from ten feet away look convincingly like wood.
Two flavors exist. WPC (wood-plastic composite) blends recycled wood fiber with plastic. Trex is the category inventor and dominant brand. PVC boards like Azek are fully synthetic, lighter, slightly cooler in sun, and more expensive. Both work. WPC feels more like wood. PVC lasts longer and resists moisture better.
The one thing composite still can't solve is heat. Dark composite in direct afternoon sun reaches 140°F and above. That will burn bare feet, keep dogs off the surface, and make the deck unusable during the hottest hours. If your deck faces south or west with no shade, choose light composite colors or stick with wood. Lighter composite stays 30 to 40 degrees cooler than dark.
Climate compatibility
Where you live changes which material makes sense. This isn't discussed enough. A material that performs beautifully in San Diego might be a poor choice in Minneapolis.
Hot and humid (Southeast, Gulf Coast) is the worst environment for pressure-treated. Mold, mildew, and algae thrive on the porous surface between sealing cycles. Composite with anti-mold capstock handles it best. Cedar does OK with annual cleaning.
Freeze-thaw (Northeast, Upper Midwest, Rockies) is hardest on sealed surfaces. Water gets into micro-cracks, freezes, and pops the seal off. PT decks in snow country lose their finish faster than anywhere else. Composite wins here because there's nothing to crack or peel.
Hot and sunny (Southwest, inland California, Texas) is the one climate where composite requires a specific precaution: use light colors. Dark composite in Phoenix or Tucson is genuinely unusable without shoes during summer afternoons.
Installation details that affect longevity
Fasteners. PT requires stainless steel or ACQ-rated fasteners. Standard galvanized screws corrode in contact with copper-treated wood. Cedar takes any corrosion-resistant fastener. Composite uses hidden fastener systems or color-matched screws for a clean surface.
Gapping. All three materials expand and contract differently. PT needs the largest gap (1/4 inch between boards) because it ships wet and shrinks as it dries. Cedar gaps at 1/8 inch. Composite requires manufacturer-specified gapping; Trex calls for 1/4 inch end-to-end on 16-foot boards and 3/16 inch side-to-side.
Joist spacing. Wood decking (PT and cedar): 16 inches on center standard. Composite: 16 inches for straight runs, 12 inches for diagonal or picture-frame installs. Wider spacing causes composite to sag between joists. This is a framing decision that happens before any decking goes down. Get it wrong and the fix is tearing up the entire surface to add blocking.
Making the call
Selling within 5 years: pressure-treated. No reason to invest in longevity you won't see.
Staying 10+ years and honest about hating maintenance: composite. It costs more today and saves you 10 Saturdays and $3,000+ over the next decade.
Want a real-wood look and will actually maintain it: cedar. Cheapest 20-year option on paper, but only if you keep the sealing schedule. Be honest with yourself about whether that will happen.
Hot sunny climate: wood (either kind) or light-colored composite. Dark composite in full sun is a deal breaker.
Before ordering materials, run the board count through the Tallyard deck calculator. Knowing your exact joist, beam, and decking quantities keeps contractors honest and avoids the surprise mid-project lumber run that always happens with a bad estimate.
Frequently asked
Is pressure-treated really the most expensive option over 20 years?
If you include sealing costs ($150-300 per application × 10 applications = $1,500-3,000) and the near-certain need to replace surface boards around year 15 ($8,000-12,000), yes. Total 20-year cost for a 320 sq ft deck reaches $27,000-30,000. Cedar totals $14,000-15,000. Composite totals $19,000-20,000. The cheapest to install is the most expensive to own.
How long does composite decking actually last?
Modern capped composite (Trex Transcend, TimberTech AZEK, etc.) carries 25-50 year warranties against fade and stain. Real-world data is still accumulating since the capped products only date to ~2015. First-generation uncapped composite from the 2000s had significant problems; current products are a different material. Expect 30+ years from any premium brand installed correctly.
Does composite get too hot to walk on barefoot?
Dark colors in direct afternoon sun absolutely do — surface temperatures can reach 140°F+. Light colors (sandy browns, tans, grays) stay 30-40°F cooler. PVC boards (Azek) run slightly cooler than WPC (Trex). If your deck faces south or west in a warm climate, light composite or wood is the right call.
Can I mix composite surface boards with a pressure-treated frame?
That's the standard approach. The frame (joists, beams, posts, ledger) is always pressure-treated regardless of surface material. Your material choice only affects the walking surface, which represents about 40% of total material cost.
Why does cedar cost less than composite over 20 years?
Cedar's installed cost is similar to PT ($12,000 for 320 sq ft at mid-range), and it doesn't need replacing at year 15 like PT does. The sealing cycle costs less because cedar only needs it every 2-3 years (7 events) vs PT's every 1-2 years (10 events). But this only holds if you actually maintain the sealing schedule. Most people don't.
What's the difference between WPC and PVC composite?
WPC (wood-plastic composite) is ~40% wood fiber mixed with plastic — Trex is the classic example. PVC is fully synthetic — Azek pioneered this. PVC is lighter, slightly cooler in sun, more moisture-resistant, and more expensive. WPC feels more like wood and costs less. Both are valid; the choice is mostly about feel and budget.
Do I need to let pressure-treated lumber dry before building?
Ideally yes. PT ships wet. Boards that are fastened immediately will warp and cup as they dry over 3-6 months. Good installers let PT acclimate for 2-4 weeks in a flat stack with stickers between layers. Many contractors skip this step — ask directly whether they acclimate and push back if they don't.
How do I know my joist spacing is right for composite?
Check the manufacturer's installation guide for your specific product. Standard: 16" on center for straight runs, 12" for diagonal or picture-frame layouts. Trex Transcend also requires 12" OC for 45°+ angles. Wider spacing causes visible sag between joists and voids the warranty. This must be decided at the framing stage before any decking goes down.
Sources
- NADRA — North American Deck and Railing Association — Industry reference for deck construction standards and best practices
- Trex — Installation and Technical Guide — Joist spacing, gapping, and fastener requirements for capped composite decking
- AWC — American Wood Council Span Tables — Structural reference for deck framing with PT, cedar, and engineered lumber
- HomeGuide — 2026 Deck Cost Report — Current installed cost ranges for all residential deck materials
- Angi — 2026 Deck Building Costs — Labor and material cost data by material type and deck size