Cedar vs. Pressure-Treated Lumber for Decks: A Builder's Comparison
Compare cedar and pressure-treated lumber for deck building: cost, lifespan, appearance, maintenance, and environmental impact. Which should you choose?
title: "Cedar vs. Pressure-Treated Lumber for Decks: A Builder's Comparison" description: "Compare cedar and pressure-treated lumber for deck building: cost, lifespan, appearance, maintenance, and environmental impact. Which should you choose?" date: "2025-01-05" author: "Cosyslabs Team" category: "deck" tags: ["deck", "cedar", "pressure-treated", "lumber", "comparison"] readingTime: 7 relatedCalc: "lumber"
When you start pricing out deck lumber, you'll quickly run into the same question every builder faces: cedar or pressure-treated? Both are natural wood. Both work outdoors. But the similarities end there. This head-to-head comparison covers cost per board foot, real-world lifespan, appearance over time, maintenance requirements, the chemistry inside PT lumber, and environmental factors — so you can make the right call for your project and budget.
Before you buy, use our lumber calculator to estimate board counts and total cost for either species.
The Quick Answer
- Choose pressure-treated if you're building on a budget, want low first-year maintenance, or are using the lumber for structural members (posts, joists, beams).
- Choose cedar if appearance matters, you prefer natural chemistry, and you're willing to pay 2–3× more per board.
Most professional builders use PT for the substructure (joists, beams, posts — where appearance doesn't matter) and then offer cedar or composite as the visible decking surface.
Cost Per Board Foot
Lumber prices fluctuate with commodity markets, but the relative cost ratio between cedar and PT is consistent.
| Species / Product | Typical Price (2×6×16 ft board) | Board Feet per Board | Cost per Board Foot | |------------------------------|----------------------------------|----------------------|---------------------| | #2 Pressure-Treated SYP | $14–$18 | 16 bf | $0.88–$1.13 | | Western Red Cedar (common) | $36–$52 | 16 bf | $2.25–$3.25 | | Cedar (clear, vertical grain) | $72–$96 | 16 bf | $4.50–$6.00 | | Incense Cedar | $30–$44 | 16 bf | $1.88–$2.75 |
Prices at national home centers, June 2025. Regional variation can be ±30%.
For a 16×16 ft deck (256 sq ft) using 2×6 decking boards at 16 ft lengths:
- PT decking: approximately $480–$620 in lumber
- Cedar common: approximately $1,150–$1,670 in lumber
- Cedar clear: approximately $2,300–$3,070 in lumber
That delta compounds quickly on larger decks. If budget is your primary driver, PT wins decisively.
Lifespan
Lifespan depends on climate, drainage, maintenance, and the specific wood product — but here are realistic ranges based on builder experience and manufacturer data:
| Material | Expected Lifespan (with maintenance) | Expected Lifespan (neglected) | |-----------------------------|--------------------------------------|-------------------------------| | Pressure-Treated (ACQ/CA) | 15–25 years | 10–15 years | | Western Red Cedar | 20–30 years | 12–18 years | | Cedar (clear, dry climate) | 30–40 years | 20–25 years |
Cedar edges out PT in longevity because its natural oils resist moisture and decay intrinsically, not via a chemical treatment that can leach out over time. However, the gap narrows significantly in above-ground applications where PT retentive levels are not depleted by soil contact.
Chemical Treatments in PT Lumber
This is where many homeowners have questions — and rightly so.
Old CCA (chromated copper arsenate): Phased out for residential use in 2004. Contained inorganic arsenic. If you have a deck built before 2004, the lumber likely contains CCA. Do not burn it, and sand with a respirator.
Modern ACQ (alkaline copper quaternary): The most common treatment today. Uses copper and a quat compound (similar chemistry to pool algaecide). Safe for contact once dry, but highly corrosive to standard zinc-plated fasteners — always use hot-dipped galvanized, stainless steel, or fasteners specifically rated for ACQ/CA lumber.
CA-B (copper azole): Similar copper content to ACQ. Also requires compatible fasteners. Slightly lower copper content than ACQ in some formulations.
Bottom line: Modern PT lumber is safe for skin contact once dry. The EPA reviewed ACQ and CA extensively before approving them. However, if you're building raised garden beds or a play structure where soil contamination is a direct concern, cedar is the more conservative choice.
Appearance Over Time
Year 1
PT lumber arrives with a greenish cast from the copper treatment. It's often still wet from the pressure-treating process, which causes checking (surface cracks) as it dries. It cannot be stained immediately.
Cedar arrives a warm reddish-brown. It can be stained or sealed right away (once the mill glaze wears off, about 2–4 weeks). It looks premium from day one.
Years 2–5 (Untreated)
Both species weather to a silver-gray patina. This is a natural process called photodegradation. Many homeowners actually like the weathered silver look — it's the same effect you see on coastal shingle siding. Cedar's silver-gray is considered more attractive than PT's gray because PT can develop a blotchy or streaked appearance.
Years 5+ (With Stain/Seal Maintenance)
Maintained cedar holds color beautifully and develops no checking. Maintained PT retains a brown tone but the surface becomes more fibrous over time as the softer wood fibers wear away.
Maintenance Schedule
Pressure-Treated
| Task | Frequency | Notes | |--------------------------|-------------------|-----------------------------------------------| | Wait before sealing | 6–12 months | PT must dry before it accepts sealers | | Apply water repellent | Every 2–3 years | Prevents checking and surface cracking | | Apply penetrating stain | Every 3–4 years | Once wood is dry enough to accept pigment | | Replace boards | 15–25 years | Replace individual boards as they cup or split |
Cedar
| Task | Frequency | Notes | |--------------------------|-------------------|-----------------------------------------------| | Apply oil-based sealer | Year 1 (after glaze off), then annually | Cedar absorbs sealers readily | | Apply semi-transparent stain | Every 1–2 years | Cedar's open grain holds pigment well | | Light sanding before refinishing | Every 3–4 years | Removes UV-damaged surface fibers | | Replace boards | 20–30 years | Cedar is less likely to cup than PT |
Cedar requires more frequent sealing than PT — roughly every 1–2 years vs. every 2–3 years for PT. This is cedar's biggest practical disadvantage. If you're not prepared for annual maintenance, PT or composite is a better long-term choice.
Staining and Sealing: What Works Best
For PT Lumber
- Best product type: Oil-based penetrating stain or a water repellent with UV inhibitors
- Wait time: 6–12 months from installation (the "water bead test" — if water beads, the wood is still too wet)
- Application: Brush or roller; avoid spraying because penetration is critical
- Top picks: Ready Seal, Armstrong Clark, or Defy Extreme for semi-transparent; TWP (Total Wood Preservative) for maximum penetration
For Cedar
- Best product type: Oil-based penetrating stain or pure tung oil (avoid film-forming products — they peel on cedar)
- Wait time: 2–4 weeks (just enough for mill glaze to weather off)
- Application: Brush and back-brush; cedar drinks stain fast, so work in manageable sections
- Top picks: Cabot Australian Timber Oil, Penofin Western Red Cedar formula, or Ready Seal in cedar tones
Avoid solid-color deck stains on either species — they're essentially paint, they trap moisture underneath, and they peel dramatically within 2–3 years on horizontal surfaces exposed to weather.
Environmental Considerations
Pressure-Treated: Sourced almost exclusively from Southern Yellow Pine, which is rapidly renewable and grown on managed plantations in the southeastern US. However, the ACQ/CA chemical treatment adds copper to the wood, which can leach into soil and waterways near ground-contact applications. Not recommended directly in vegetable gardens or near water.
Western Red Cedar: Old-growth cedar is not a sustainable choice. Look for FSC (Forest Stewardship Council) certification to confirm second-growth sourcing. Cedar grows relatively slowly compared to SYP, so responsibly sourced cedar is worth seeking out. No chemical treatments means zero leaching concern.
Carbon footprint: Both are dramatically lower in embodied carbon than concrete or steel. Cedar has a slight advantage because it requires no energy-intensive chemical processing.
When to Use Each
| Situation | Best Choice | |------------------------------------|-----------------| | Joists, beams, and posts | PT (required) | | Decking on a tight budget | PT | | Decking where appearance is key | Cedar | | Ground contact or buried members | PT (UC4B rated) | | Children's play structures | Cedar or modern PT | | Near a pond or vegetable garden | Cedar | | Low-maintenance homeowner | PT or composite | | High-end build, premium look | Clear cedar |
Calculate Your Lumber Needs
Whether you go PT or cedar, use our lumber calculator to convert your deck square footage into board counts, account for waste factor, and compare costs side by side. If you need to convert board feet to cubic meters or work with metric pricing, unitconvertall.com has dedicated lumber unit converters. For getting a formatted estimate you can email to your lumber yard, pdfconvertall.com can convert your spreadsheet to a clean PDF — no account required. The team at Cosyslabs built these tools to keep estimating fast and free.
FAQ
Can I mix cedar decking with PT framing? Yes — this is actually the most common professional approach. Use PT for all structural members (posts, beams, joists, ledger) and cedar for the visible decking surface and railing. Ensure your fasteners are compatible with PT (hot-dipped galvanized or stainless steel).
Is pressure-treated lumber safe for a vegetable garden? The EPA states that ACQ- and CA-treated lumber is safe for raised garden beds, but many gardeners prefer cedar as a precaution. If you use PT near edible plants, line the interior with heavy plastic sheeting as a barrier. Never use CCA-treated lumber (pre-2004 green boards) near food crops.
Why does PT lumber check and crack? PT lumber is sold "wet" — it's saturated with water-borne preservative solution. As it dries after installation, surface fibers shrink at a different rate than the core, causing surface checks (shallow cracks). These are cosmetic, not structural. Proper sealing after the wood dries minimizes future checking.
Can cedar be used for structural deck members? Technically yes — Western Red Cedar has adequate structural values for light framing — but most engineers and building departments require pressure-treated or approved alternatives for ground-contact or high-moisture structural members. Using PT for structure and cedar for decking is the safer, code-compliant path.
Which wood is better in a wet climate like the Pacific Northwest? Cedar performs exceptionally well in wet climates — it's native to the Pacific Northwest and naturally adapted to persistent moisture. PT also performs well but tends to develop more surface mold in continuously wet conditions. More frequent cleaning and sealing is required in either case.
Does cedar attract insects? Cedar's natural oils (primarily thujopsene) repel many insects, including moths and some beetles. It is not as resistant to subterranean termites as PT, however. In termite-prone regions (Southeast, Southern California), always use PT for ground-contact members regardless of species preference for decking.
How do I tell if my old deck is CCA-treated? CCA-treated lumber typically has a greenish tint that doesn't fade over time and is heavily oxidized on the surface. Boards installed before 2005 are likely CCA. You can purchase test kits (Everdry or similar) that detect arsenic in the wood. When in doubt, treat all pre-2005 lumber as potentially CCA: wear gloves when handling, don't sand without a respirator, and never burn it.