Cedar vs Pressure Treated Deck: What’s the Difference?

Before I built a deck, I’d never considered anything beyond pressure treated lumber as the primary building material for a deck. It wasn’t until I saw a friend’s red cedar deck up close for the first time that it dawned on me that cedar was an excellent alternative to pressure-treated lumber, but I was curious what the difference was between a cedar vs. pressure treated deck.

A deck built with pressure-treated lumber is cheaper than cedar. The difference in price varies, but expect to pay anywhere from 50% more to over double for cedar versus pressure-treated lumber. Pressure-treated lumber also requires more frequent and laborious maintenance, such as staining or painting every few years. Cedar requires only an annual wash and rinse.

Cost and maintenance are the primary differences between the two-deck material options. There are other issues at play as well, one being that pressure-treated lumber is full of chemicals designed to withstand rot and moisture. Cedar is free of any chemicals, making it a more environmentally friendly choice – and easier to handle.

Whichever lumber you decide to use for your deck, make sure you do your research as the two types of decking material vary widely. Below we’ll go over all the differences between cedar and pressure-treated decking so that you can make a more informed choice before purchasing lumber for your next deck project.

Cedar Decking: Quick Overview

Cedar decking is simply a deck board, or dimensional lumber, milled from a cedar tree for use in deck construction. Cedar is the primary alternative to standard pressure-treated lumber found in every home renovation store.

Pressure-treated lumber is pine, fir, or spruce. They are lightweight and durable in outdoor applications, particularly when treated with chemicals. Cedar is also durable but has natural rot-resistant characteristics that negate the use of chemicals. Most home reno stores also carry cedar decking and dimensional lumber as an alternative to standard pressure-treated lumber.

The most common species of cedar lumber found in retail stores is Western Red Cedar, by far. It is found throughout Western North America and can grow over 200’ tall. Due to its great size and abundance, it is the primary species of cedar used for deck construction. Typically it’s the only species of cedar lumber you’ll find at Home Depot, for instance.

Other species can sometimes be found at sawmills or specialty lumber stores, such as White or Yellow Cedar, but these can be costly and more expensive since the trees are physically smaller and less abundant.

Pros

• Aesthetically pleasing
• Environmentally Friendly
• Naturally Weather-Resistant
• Repels Insects
• Accepts Sealers and Stains
• Dimensional Stability – resistant to shrinking and twisting
• Poor moisture retention

Cons

• Fades to a darker, weathered gray in exposed sunlight
• Ground contact will result in rot and decay
• Regular maintenance required to maintain the natural color
• Prone to wear in high-traffic areas
• Cost

Pressure Treated Wood: Quick Overview

The classic decking material, pressure-treated wood, has undergone many different versions over the years. Currently, the predominant type of pressure-treated wood is of the “copper” variety, and there are two main types with acronyms like “CA” and “ACQ”.

“CA” stands for “copper azole”, which is the chemical preservative that protects the wood. “ACQ” stands for “amine copper quat”, which is another type of copper preservative. You may recall the old green wood, which was extremely effective as the primary pressure treated decking material. However, that wood used arsenic as a preservative, which is no longer allowed in residential deck building applications.

The pressure-treated copper lumber products are effective, but the buyer needs to beware that there are up to 12 different levels of pressure-treated lumber available. For instance, PT deck boards have much less preservative than a PT 6×6 or 4×4 rated for ground contact.

Labels on PT lumber that read UC4A, B, and C indicate PT lumber rated for ground contact in general, heavy, and extreme applications, respectively. You won’t find those ratings applied to PT deck boards, which will more likely be UC3A. Pay attention to the small white labels affixed to the end of each lumber piece to be sure the level of pressure treatment applied to the lumber you intend to purchase.

What is Pressure Treatment?

Pressure-treating a piece of lumber means that the lumber is blasted with a preservative and water mixture at an ultra-high psi – up to 150 p.s.i. Over time the water evaporates from the PT lumber, leaving behind the preservative.

The actual process of the treatment involves a stacked unit of lumber entering a sealed chamber. The air is slowly removed and the chamber fills with the heated preservative mixture. The chamber is then pressurized, which forces the preservative into the lumber. The vacuum opens the wood cells so that more preservatives can enter the lumber.

Lastly, you’ll notice that your PT lumber seems to have small indentions in it all up and down the face and sides. This is called “incising” in which a machine scores lumber destined to be treated with preservative, as it allows the preservative to penetrate more effectively. But as we’ll see below, not all wood species accept preservatives the same.

What Type of Trees are Used for Pressure-Treated Wood?

The same tree species used for standard non-treated lumber are used in pressure-treated applications. For instance, much of the lumber in the Southeastern U.S. used in framing is SYP – Southern Yellow Pine. Pressure-treated lumber in the same area would likely be the same species – mills in the area would process both types.

Other common species particularly in the Northern U.S. and Canada, are Spruce, Pine, and Fir. This designation reads “SPF” on the lumber. In terms of strength, SYP is rated slightly higher than SPF.

Some other species include Douglas Fir, Larch, Hemlock, and European Spruce. Fir, Larch and Hemlock, in particular, are not as effective under pressure treatment as they do not hold preservative as well as SYP or some SPF species. For instance, a ground contact rated PT hemlock 6×6 will not be as durable as a similar rated pressure-treated SYP 6×6.

Regardless of the species, pay attention to the grade of lumber. Select,#1, and #2 indicate wood with no or few knots and are suitable for all framing applications.

When selecting a grade of wood, understand that “select” or “premium” grades are pieces of lumber with next to no blemishes or knots. The use of this grade of lumber would suffice more for fine carpentry and finish pieces instead of framing. These higher grades do exist for PT lumber, but they are more expensive and not as common.

Lumber graded #3 or utility will be full of knots and other defects. You will want to avoid using it for dimensional lumber and is only applicable in light framing applications, such as a small shed or doghouse. While cheaper, you want pressure-treated lumber with a #1 or #2 grade.

Lastly, the label on a piece of lumber can tell you a lot about that wood. Take, for instance, the level of preservative in a piece of PT lumber. There will be a decimal number on the label, such as .40. That’s the number of ounces per board foot (a board foot is 1’ x 1’ x 1”). Anything over .40 is good for ground contact.

If you want to bury a post in the ground, there is PT lumber with the acronym PWF – permanent wood foundation – which has very high amounts of preservative. It is costly and often not sold at big box reno stores, but is incredibly durable.

Pros

• Economical
• Durable
• Different grades available
• Comes in various treatment levels
• Widely available in many different dimensions

Cons

• New wood is often saturated
• Must use gloves and mask when handling and cutting
• Requires special disposal of scrap – cannot burn it
• Aesthetically not appealing
• Often made from lower-grade lumber – more cracking/warping

Cedar vs Pressure Treated Deck

Both types of lumber have useful applications and can both be enjoyed by deck owners for many years. But which is better?

The easiest answer is that PT (pressure-treated) lumber will appeal to some while cedar others. Why? PT lumber is excellent because it is cheap and stains easily. Once dry, a solid deck stain will protect your deck for years if properly maintained.

On the other hand, if you want a natural look to your deck, then cedar is your choice. It looks stunning, but keeping it that nice, natural cedar color takes work unless you don’t mind it weathering into a gray. Let’s take a closer look at the comparisons between the two types.

Durability & Lifespan

The lifespan of PT and cedar decking has much to do with the environment and proper maintenance. If you left both alone, you’d find that PT decking has a lifespan of about 5 years less than cedar decking. A properly constructed cedar deck with average environmental conditions will last around 20 years. A PT deck under the same circumstances will last around 15 years.

Rotting, Decay, and Insects

Cedar does have some decay resistance. There are extracts in the sap that make it resistant to moisture uptake. That’s great news for cedar decking owners, but it doesn’t mean cedar won’t decay or rot. It will if you don’t take care of it.

For the same reason, it is durable, cedar also is not insect-friendly. Insects enjoy moist locations, and since cedar resists moisture naturally, it is not popular with most bugs. That isn’t to say a wasp wouldn’t make a nest under the joists – they still would – but the cedar would resist burrowing insects such as ants.

PT lumber is less resistant to rot and decay. Eventually, the preservative will leach out of your PT lumber unless you have sealed and stained it. Regular sealing and staining will help stave off rot and extend the longevity of your PT decking, but be prepared to treat your deck every couple of years or so, particularly as it ages.

Warping and Splitting

Since cedar does not soak up moisture to the extent that PT lumber can, it does not crack or split as much. Moisture intake means that wood changes shape – the mass of the water will distort the wood.

Or, when your PT wood is new, there is still lots of water leftover from the treatment process. Once installed on your deck, it will dry out thoroughly and experience movement. Lower grades of PT lumber in that situation will crack or split. Proper installation will mitigate some of the cracking and splitting, but even higher grade PT lumber will see cracking on a new deck install as nearly all PT lumber is moist upon leaving the store.

Cedar lumber is more resistant to cracking, but beware: pay close attention to the cedar decking you purchase. The end grain of each piece is critical in telling you whether or not you’ve got a worthy piece for your deck. You want cedar lumber with most – if not all – heartwood.

Heartwood is the center of a tree and is where the deep, rich colors – of cedar and any other species – exist and give the wood its visual character. It is also the densest part of the tree and less moist than the outer portion – the sapwood.

Sapwood is typically lighter and is on the very outer rings of the tree. If you can see two different colors on the end-grain of your cedar lumber, that means there is sapwood. Sapwood carries the water in the living tree, is more susceptible to insects and rot, and is prone to maintaining moisture. These pieces will also warp and crack more. Cedar decking made with sapwood/heartwood mix will crack more and not last as long.

Scratching and Surface Durability

Cedar is a softwood. It is great to work with and easy to handle, but it scuffs easily and will wear quickly in high traffic areas. If used in stairs, or in areas where you are moving around deck furniture frequently, you’ll notice marks much more than you would if you used pressure-treated lumber.

While PT lumber may stand up better in high traffic areas, you’ll notice wearing in the pressure treatment if you have opted not to stain your PT decking. For instance, copper treated lumber (that is copper in color) will fade in high traffic areas.

Maintenance

Pressure-treated lumber needs regular treatment. How regular? Annual cleaning with deck and wood cleaner for starters. You can pressure wash it but only gently. Get too close or apply too much pressure and you’ve damaged your wood. It also needs to be sealed. Transparent sealers and waterproofers are typically only good for a max of two years – or just one.

Semi-transparent and solid stains are often sold as two-in-one stains and sealers. The less transparent, the longer it will last. Why? Damage from ultraviolet light is probably the number one factor – along with moisture – in damaging your decking. A solid stain will provide an impermeable barrier between the sun, moisture, and decking.

PT wood can also be painted. A latex primer and paint will do the job and achieve the same result as a solid stain. The important thing to note about painting is that you absolutely must use the appropriate type of exterior paint. Any home reno store will have paint exclusively for decking.

Another aspect to consider is that you do not want to paint your PT decking too soon after purchasing your lumber. Why? It is simply too wet to accept paint. You’ll have to let your decking dry for weeks, if not months, before priming and painting it.

Finally, you can sand your deck, and you should in most cases. Why? It will improve the surface of your wood and allow the stain to penetrate better. A uniform surface will accept stain and improve the look of your wood. Sand after pressure washing, as the pressure wash, will cause the outer grain of the wood to raise slightly. Sanding will then properly re-surface the wood.

Remember, a pressure-treated deck should be sealed, stained, and/or painted soon after being installed. Sunlight will destroy the wood if left untreated.

The same general rules of preservation apply to Cedar decking. Keeping it clean is crucial, whether you opt to stain it or not. Scum, mildew, dirt, or any other general surface wear that isn’t removed will allow moisture to penetrate the wood and prematurely damage the wood. An annual wash with soap and water is sufficient – over the counter products may damage cedar unless specifically designed for cedar decking.

With cedar decking, you have 3 options. First, you can do nothing to it and regularly clean it. If kept clean and away from ground contact, you’ll have a sound deck for at least 15-20 years. The issue is color – it will turn gray faster. If that color and tone appeal to you, then this is the simplest option.

The second option is to put a transparent coating of water repellant on the cedar decking. This allows the cedar color and tone to show through but gives it enhanced protection from moisture. It will also delay the weatherization of the wood. Protecting the wood from moisture ensures its shape will not change, reducing cracking and twisting. In that way, your gaps between deck boards are less likely to shrink or swell.

How long depends on how much sun the deck is exposed to – if it is in full sun, expect moisture resistance but also be prepared to see your deck change to gray regardless of the transparent water repellent coating. You will also need to re-apply no more than every two years – more likely, you’ll apply a coating annually.

Your final choice for the cedar is to stain the decking. Just like PT wood, there are a variety of semi and full stains to choose from.

A semi-transparent oil-based stain is effective because it penetrates the cedar more effectively than a latex-based stain. For that reason, oil-based stain offers more durability and a longer-lasting finish. Latex-based stain forms a film and does not penetrate.

On the other hand, the latex-based stain is easier to apply and clean up, as the oil-based application can be messy as it is thin and runs all over when applied. An even coat is also difficult with oil-based stain – you will likely need at least two coats and a shady day to properly apply the oil-based semi-transparent cedar stain. Keep in mind that latex – which is water-based – will not help cedar against UV damage as oil does.

Solid-color stain requires several coats plus a coat of primer. A primer will help block any stains that might try and seep through the wood and stain, and the topcoat will be 100% acrylic solid stain. These stains are effective in keeping both moisture and UV light from damaging your cedar.

The downside is that you are covering up the natural look of the cedar. While some of the grain may still be visible, the true character of the wood is altered.

Cost

Cedar is more expensive – but the gap is not huge. For instance, right now at Lowes, a 12’ x 5/4” cedar deck board is $4 more than a premium pressure-treated deck board of the same length. For an entire deck, this difference will widen significantly, however. Below let’s take a closer look at pricing.

Using the above lengths, a 12’ cedar deck board is around $23. A pressure-treated board is about $19. That equals roughly $3.20 a square foot for pressure-treated decking and $3.80 a square foot for cedar decking.

A 10’x12’ deck using PT deck boards will cost $384. The same size deck using cedar decking will cost $456. That includes the decking and not the frame or railing.

Use of PT lumber for the deck frame and cedar for the decking and railing would be a cost-effective solution and give you the cedar look without having to pay for dimensional cedar lumber, which tends to run even more expensive than PT dimensional lumber.

Verdict: What’s Better Cedar or Pressure Treated Wood for a Deck?

It depends on how you want your deck to look. If you plan on staining your deck, regardless of lumber type, then a pressure-treated deck might be the better option. It will cost you less and you’ll have to re-apply stain to pressure-treated and cedar decks with the same frequency.

If you want a more natural look and are using just a sealer or water repellant on your decking, then you’ll want a cedar deck. It will last years longer than your pressure treated decking and aesthetically will age much better. Even a cedar deck left completely untreated will age much more nicely than a regularly sealed pressure-treated deck – it’s simply one of the allures of cedar.

Conclusion

Whether you choose cedar or pressure-treated lumber for your next deck project, keep in mind that you ultimately have the power to determine how long your deck will last. Regular maintenance is crucial to maintaining a long-lasting deck.

Remember that just because you’ve chosen cedar, that it doesn’t mean you can build it and forget about it. Cedar requires just as much maintenance as pressure-treated lumber if you want it to last. Although it is a premium decking option, consistent care is still mandatory.

As always, thanks for taking the time to peruse this article. I hope it assists you when you plan the materials for your next deck project. If you have any comments or suggestions for how to make this article better, then don’t hesitate to drop me a line.