Pressure-Treated Wood vs. Cedar: What to Use for Outdoor Projects

How Each Material Is Made — and Why It Matters

Understanding what these two materials actually are helps you make the right call before a single board is cut.

Pressure-treated wood is typically southern yellow pine or a similar softwood that has been infused with chemical preservatives under pressure. The most common modern treatment is ACQ or copper azole, which replaced the older arsenic-based CCA formula phased out for residential use in the early 2000s. These copper-based compounds penetrate deep into the wood fibers and make the lumber highly resistant to fungi, termites, and moisture-driven decay.

Cedar — most often western red cedar in the U.S. — contains naturally occurring oils and tannins that act as built-in preservatives. No chemical treatment is added. This makes cedar inherently resistant to rot and insect damage, though less so than pressure-treated lumber in the most extreme ground-contact or wet conditions.

The production difference has downstream effects on handling. Pressure-treated lumber should be cut with a dust mask, kept away from open flames until fully dried, and its offcuts should not be burned. Cedar carries no such handling restrictions under normal residential use.

Comparing Durability, Cost, and Appearance

No single lumber wins on every dimension — the right choice depends on which trade-offs matter most for your specific project.

On durability, pressure-treated wood has the edge in ground-contact situations. Posts set directly in soil, deck ledger boards fastened to the house, and any framing within six inches of grade should generally be pressure-treated. Cedar, while naturally durable, degrades faster when in prolonged contact with wet soil.

For above-grade, visible surfaces — decking boards, fence pickets, pergola rafters — cedar competes well on longevity while offering a significantly more attractive appearance. It takes stains and sealers evenly and doesn't require the extended drying time that freshly milled pressure-treated lumber does before finishing.

Cost varies by region and lumber market conditions, but pressure-treated lumber is typically less expensive per linear foot than cedar. On a large deck, that difference adds up. Some homeowners use a hybrid approach: pressure-treated framing and joists beneath, with cedar decking boards on top. This captures the structural strength of treated lumber and the aesthetic warmth of cedar where it's most visible. See our seasonal deck care guide for maintenance steps that apply to both materials.

Safety, Garden Use, and Long-Term Maintenance

One of the most common questions homeowners ask is whether pressure-treated wood is safe for raised garden beds. The current copper-based treatments used in residential lumber are considered significantly safer than the old CCA formula, but many gardeners and extension horticulturalists still recommend cedar or untreated wood for beds growing edible crops — particularly root vegetables that have direct soil contact. If you choose pressure-treated lumber for a raised bed growing ornamentals or non-edible plants, the risk concern is much lower.

For long-term maintenance, both materials benefit from periodic sealing. New pressure-treated lumber should be allowed to dry for several weeks (or until it passes the water-bead test) before applying a water-repellent sealer. Cedar can be sealed sooner but will also age gracefully to a silver-gray if left unfinished — a look many homeowners intentionally choose for fences and garden structures.

Check fasteners when you inspect either material. Pressure-treated wood's copper compounds can corrode standard steel nails and screws over time; always use hot-dipped galvanized, stainless steel, or fasteners specifically rated for treated lumber. Cedar is less corrosive but benefits from the same quality fasteners for longevity. For a broader view of keeping your home's exterior in good shape, our guide on maintaining windows and exterior doors covers similar principles of sealing and seasonal inspection.

This article is for general informational purposes only. Always verify local building codes and permit requirements with your municipality before beginning structural outdoor projects, and consult a licensed contractor for work involving load-bearing construction.