Cedar vs Pressure Treated Wood: Which Lasts Longer Outdoors?

Western red cedar heartwood resists rot on its own, but at 350 lbf it is soft, and its pale sapwood has no decay resistance. Treated pine is the safer pick for anything touching soil, while cedar wins above ground where looks and low maintenance matter. This guide gives a part-by-part pick list, the treatment categories that matter, fastener rules, and safety.

Cedar vs Pressure Treated at a Glance

The two woods stay outdoors for different reasons. Cedar relies on natural extractives in its heartwood. Pressure-treated lumber is usually southern yellow pine with preservative forced deep into the wood. The Wood Database lists western red cedar as durable to very durable against decay, and loblolly pine, a common treated species, as only moderate to low in decay resistance before treatment. That gap is why untreated pine rots quickly and why the preservative does the real work in treated lumber.

Property	Western red cedar	Treated southern yellow pine
Janka hardness	350 lbf, very soft and dents easily	690 lbf (loblolly), roughly twice as hard
Where rot resistance comes from	Natural extractives, heartwood only	Preservative forced in under pressure
Decay rating before any treatment	Durable to very durable (heartwood)	Moderate to low (heartwood)
Insect resistance	Mixed	Depends on the preservative
Weight when dry	About 23 lbs per cubic foot	Heavier and denser
Rating system	None, graded by heartwood content	AWPA use categories such as UC3B and UC4A
Sawdust concern	Plicatic acid can trigger allergy and asthma	Wear a dust mask and goggles when sawing

Sources: Wood Database for the cedar and loblolly figures, EPA for the sawing precautions.

Which One Should You Use for Each Part of the Project?

Most people ask whether cedar or treated wood is better, when the better question is which boards touch soil or stay wet. Splitting a project by exposure is the angle most comparison pages skip, and it usually ends with both woods in one build.

Part of the project	Better pick	Why
Fence posts set in soil	Treated, UC4A or higher	Constant soil moisture is the worst exposure for cedar
Fence pickets and rails	Cedar, or treated rated UC3B	Above ground and drying between rains
Deck joists and beams	Treated	Structural, hidden, and often close to the ground
Deck surface boards	Either	Cedar looks better but dents; treated lasts and costs less
Raised garden bed sides	Cedar for edibles, treated if you accept it	Cedar sidesteps the treated wood question
Pergolas and arbors above ground	Cedar	Appearance matters and nothing sits in water
Steps or edging touching soil	Treated, UC4A or higher	Ground contact needs the higher category

If your project is a deck specifically, our cedar vs pressure-treated deck comparison covers framing and surface boards in detail. This page stays with the broader decision.

What Actually Makes Each Wood Resist Rot

Cedar protection is real but uneven

Cedar’s resistance comes from heartwood extractives, so it follows the color of the board. Dark heartwood protects; near-white sapwood does not. Cheap cedar pickets with plenty of pale edge wood rot far sooner than the species rating suggests. Cedar here also means western red cedar, not the strongly scented closet wood. For that species see our aromatic cedar guide, and for the redwood alternative see cedar vs redwood.

Treated lumber is not one product

Treated wood is sorted into AWPA use categories, and the tag on the board tells you where it may go. According to the AWPA, UC3B covers exterior above-ground use that is uncoated or drains poorly, UC4A is general ground contact, and UC4B and UC4C step up to heavy and extreme duty. A UC3B board set in soil is under-protected, which is a common way treated wood fails early.

Category	Intended use	Example copper azole (CA-C) retention	Example ACQ retention
UC3B	Above ground, uncoated: decking, rails, pickets	0.06 lb per cubic foot	0.25 lb per cubic foot
UC4A	General ground contact: posts, landscaping	0.15 lb per cubic foot	0.40 lb per cubic foot

Retention figures are the AWPA standard values as summarized in a preservative manufacturer’s specification, and they vary by chemical, so read your own lumber’s tag. Our guides to UC4A vs UC4B ground contact lumber and what pressure-treated wood is go deeper on the ratings.

Treated cedar is a niche product

Searches for pressure treated cedar are common, but cedar is rarely treated, because its natural durability is the selling point. Most boards sold as treated are pine. For the full explanation, read can cedar be pressure treated.

How Each Wood Ages Outdoors

Unfinished cedar fades from warm reddish-brown to silver-gray outdoors. The color change is cosmetic, not rot, and plenty of people prefer it. To keep the original tone, plan on a UV-blocking finish; the steps are in how to treat cedar wood properly.

Treated pine ages differently. It starts out greenish or brown from the preservative and weathers toward gray too. Because pine is harder than cedar, it takes foot traffic and furniture legs better, while cedar scratches and dents under the same use. Either wood needs water to drain away from it, since constant wetness defeats both natural and chemical protection.

Fasteners: The Detail That Decides Lifespan

Cedar and treated lumber ask for the same fastener for opposite reasons. The Wood Database notes that iron fasteners can stain cedar in wet conditions, so plain steel screws leave dark streaks. Copper-based preservatives, meanwhile, are widely reported to corrode uncoated steel, which is why hot-dipped galvanized or stainless steel is the standard recommendation for treated lumber. Stainless solves both problems, and it is the one screw to use if a single build mixes cedar and treated boards.

• Use stainless steel or hot-dipped galvanized fasteners on both woods.
• Avoid bare or thinly plated steel screws, especially on cedar fences that get wet.
• Drill pilot holes near board ends on cedar, which splits easily because it is soft.
• Treat every field-cut end of treated lumber, as covered in how to seal cut ends of pressure-treated wood.

Safety and Handling

The older worry about treated wood was CCA, which contains arsenic. According to the EPA, manufacturers voluntarily stopped making CCA-treated wood for homeowner uses in December 2003, and modern residential lumber uses copper-based preservatives. The EPA still advises goggles and a dust mask when sawing, and says treated wood should not be burned in residential settings or reused as mulch.

Cedar has its own caution. The Wood Database reports that western red cedar contains plicatic acid, which can cause allergic reactions and occupational asthma, so cedar dust deserves a respirator too. For edible beds, see our guide on whether pressure-treated wood is safe for a garden.

Cost: Compare Cost Per Year, Not Price Per Board

Cedar usually costs noticeably more per board than treated pine, so treated lumber wins on price on any given day. A fairer test is cost divided by useful years, including the finish you will buy. Use this formula with your local yard’s prices: (board cost + fasteners + finish over its life) divided by the years you expect it to last. Cedar’s sapwood and soft surface shorten its life in ground contact, so it pays back mainly above ground.

Frequently Asked Questions

Is pressure treated wood better than cedar?

It depends on where the board goes. Treated pine rated for ground contact (UC4A or higher) outlasts cedar in soil, and it is the harder wood. Cedar heartwood resists rot on its own above ground and looks better with less work. For a fence, use treated posts and cedar boards.

Which lasts longer, cedar or pressure treated?

In the ground, correctly rated treated pine lasts longer, because cedar’s natural resistance is limited and its sapwood has none. Above ground, both can last for many years if water drains off them. Exact years vary too much by climate and installation for any single number to be honest.

Can you use cedar for fence posts?

You can, but posts are the weak spot of a cedar fence. They sit in wet soil, the harshest exposure for any untreated wood, and cedar is soft at 350 lbf. Treated posts rated UC4A or higher are the usual choice, with cedar pickets and rails above ground.

Is cedar rot resistant?

Western red cedar heartwood is rated durable to very durable against decay by the Wood Database, but the pale sapwood is not, and insect resistance is only mixed. A board with a lot of sapwood rots much faster than a clear heartwood board, so grade matters as much as species.

Is pressure treated wood safe for garden beds?

Residential lumber has not used CCA since the manufacturers’ voluntary phase-out in December 2003, and current copper-based preservatives are registered by the EPA for general use. Many gardeners still choose cedar for edible beds to avoid the question. Our treated wood in the garden guide covers the details.

Bottom Line

Use treated lumber rated UC4A or higher for anything in or touching soil, and cedar for visible above-ground parts where you want the look and lighter upkeep. Fasten both with stainless steel. For most fences and decks the best answer is not one wood but both, each in its right place.