Does Cedar Need To Be Treated For Outdoor Use?

Does Cedar Need To Be Treated For Outdoor Use

If your project would benefit from beauty, and aesthetics will be important for the finished workpiece, one of the woods that quickly comes to mind is cedar. It’s tight-grained and weather-resistant against outdoor elements, and its natural beauty makes gorgeous decks, arbors, trellises, and fences. It also takes well to sanding to a smooth finish and is a good choice for bench seats and children’s play structures.

Its chemical properties make it naturally weather-resistant and repels most bugs, which makes it an appealing choice for outdoor projects. The most readily available cedar is western red cedar.

It will tend to crack over the years and will benefit from an occasional refinishing. Yes, a refinishing, which suggests an initial refinish. This is what we want to talk about today.

Is Cedar a Hardwood?

While cedar has many useful qualities, its hardness isn’t one of them. No, cedar is not a hardwood.

This beautiful, versatile wood, known for its spicy aroma, is a softwood. It is popular because of its good looks, light weight, and usability. Its warm, red tones make interior applications a natural, whether it be for ceilings, walls, and wainscoting. It is also favored for closet walls and trunks where that spicy aroma can be imparted to clothing for a fresh smell.

For outdoor use, cedar is a good choice for siding, shingles, decks, arbors, pergolas, and fences because of its natural resistance to the elements. While it is considered a durable wood, it is not completely resistant to rot. It should not be used in direct contact with the ground or set in concrete, as this will speed up decay and rot. And while generally resistant to most bugs, there are some kinds of insects that can cause damage.

While western red cedar is the most commercially available species, there are others that offer their own benefits to woodworking projects indoors and outdoors, including:

Incense Cedar. Light brown in color with streaks of red, this cedar is a favorite of furniture makers who use it for sweet-smelling clothes, drawers, closets, and trunks. This cedar is also used to make pencils.

Port Orford Cedar. Only growing in southern Oregon and northern California, this cedar is not readily available. As you can imagine, it’s very expensive. Its spice and lemon blended aroma makes it a favorite for things like children’s toys.

Alaskan Yellow Cedar. Creamy yellow in color, this cedar grows in Alaska and Canada. It is one of the harder cedar varieties, and its strength and natural weather resistance makes it suitable for park benches and even marine construction.

On the Janka scale of hardness, it ranks toward the softer, depending on the species being tested. Where yellow birth has a Janka score of 1260 and northern red oak a score of 1290, the various cedar species we’ve mentioned score as follows:

  • Incense cedar: 470
  • Port Orford cedar: 720
  • Alaskan yellow cedar: 580
  • Western red cedar: 320

While the 320 Janka score of western red cedar is low, and low equals soft(er), that doesn’t necessarily mean that western red cedar is weak. But, it would tend to suggest that it is easily dented and would not be a good choice for flooring or other uses that could be subject to impacts.

It would still be a good choice for an outdoor table, or a trellis for roses and clematis to climb, or for a pergola over your patio.

How Does Cedar Compare to Pressure-Treated Lumber?

While southern yellow pine is the wood most usually pressure-treated, it is interesting to note that cedar is also pressure-treated. Fir is also a common pressure-treated wood.

Pressure-treated wood is wood that has been infused with preservatives to protect the wood from decay and insects. The wood is placed in a tank that is depressurized and filled with chemical treatment. The tank is then pressurized, and the chemicals penetrate the wood’s pores through and through.

That saturation provides protection for as many as 2-3 decades before the wood will eventually fail and need to be replaced, whether in decking, fences, fence posts, and other outdoor applications. Some pressure-treated wood is rated as “ground contact,” meaning it can safely be used in direct contact with the ground – fence posts, decks, pergola posts, trellis posts, and raised planting beds, for example.

After the wood is milled, it is run through a machine that perforates the surface with hundreds of incisions to allow deep penetration of the chemical treatments. This makes pressure-treated wood not especially attractive. The wood used in pressure treatment is also usually of a lower grade, so it doesn’t start as attractive in the first place.

Wood that has been pressure-treated needs time to cure – to dry before it is used. It will not accept paint well until it is fully dry since it will shrink, warp or crack in the process of drying.

A stain, whether semi-transparent or solid, will hide some of the wood’s low-grade appearance and offer some protection against the sun’s UV rays. However, a finish on pressure-treated wood is not necessary to improve its durability and rot/bug resistance – the pressure treatment already does that.

The process of pressure treating does not enhance the strength of the wood – what it was prior to the treatment it will be after. Pressure-treated woods can not compare with the beauty of cedar, and it certainly does not offer the scents of the various cedar wood species. If aesthetics are important to your project, cedar is the obvious choice.

Does Cedar Need Treatment To Match the Durability of Pressure-Treated Wood?

While a protective finish may be optional, we would recommend you nonetheless consider one. Cedar’s natural resistance to the elements and to rot and insect damage is not in perpetuity.

Cedar is about 30% more expensive than other woods and much more expensive than pressure-treated lumber. You will want to protect your investment in the more expensive wood to help it last longer.

Some will claim that untreated cedar may last for between 15-30 years, although we tend to believe it is in the lower range of that claim. Pressure-treated wood, untreated, has a useful lifespan of 20 – 30 years by comparison.

Most who regularly work with cedar do suggest waterproofing cedar for outdoor use. Cleaning and general maintenance of your outdoor project will help prolong the life of the cedar.

There are three effective ways to waterproof your cedar:

  • Linseed or tung oil will create a beautiful and protective finish;
  • A sealant like polyurethane, varnish, or lacquer, will seal the cedar; and,
  • A finish and water-proofing stain/sealant will seal the cedar.

We’ve written of linseed oil in previous articles and recommend you take a look at one of those articles here. Of these options, we want to talk about the first one.

Boiled linseed oil is an excellent choice to finish and protect cedar. It’s a clear finish that is both durable and dries quickly. Its application is easy, and the cedar is ready to use. It offers protection from both the sun and water. It’s inexpensive, too, and creates an aesthetically pleasing appearance of an already beautiful wood.

There are several treatments worth considering beyond linseed oil, including:

  • 100% Pure Tung Oil Finish Stain and Sealer
  • #1 Deck Premium Semi-Transparent
  • Thompson’s Waterseal
  • Ready Seal Natural

These products are considered very good choices for treating cedar for outdoor use.

So, does cedar need to be treated for outdoor use? It depends. While some consider it to be optional, we believe it should be treated. It’s an expensive choice, and if you are going to spend extra money on the beauty of cedar, you ought to protect that beauty for a long life.

Here’s a beautiful set of cedar planter boxes that are getting the boiled linseed treatment.

The odds are you have worked with linseed oil on past projects and probably have it in your shop. A nice hand-rubbed clear finish will allow the natural beauty of cedar to show well, and the quick-drying and durable linseed oil finish will extend the life of your fence or trellis, or deck for many years beyond an unfinished project.