Cedar Vs. Pressure Treated Fence Posts

Cedar Wood Grades

• Naturally rot and insect-resistant woods are the heartwoods -- or the inner trunk wood -- of particular trees. Their sapwood, or their outer wood, is not particularly rot or insect resistant because it contains low levels of the necessary compounds. When shopping for supplies, it is important to differentiate between lumber made of cedar heartwood and lumber made of the sapwood. Common construction grade cedar is sapwood, while the No. 1 grade is suitable for railings and benches. Streaky cedar wood is also inferior to non-streaked products.

Pressure-Treated Lumber Grades

• How the chemicals are applied and integrated into pressure-treated lumber is an important consideration for building projects. For outdoor projects, like fence posts, look for a retention grading of at least 0.40 pounds per cubic foot, indicated as 0.40 lbs/cu. ft. Wood that has been dipped in the preservative for at least 5 minutes is more durable and resistant than wood that has had the preservative brushed or painted on and kiln-dried products are stronger than air-dried products. Douglas and Hem fir species must also be incised -- indicated by tiny knife marks -- if they are thicker than one inch. The incision allows for greater chemical penetration, which is necessary for softer woods.

Advantages and Disadvantages of Cedar

• Cedar is similar to redwood in its durability, insect and rot resistance, but about half the price. Its golden brown color is attractive and can be easily preserved with a clear finish. For those who prefer natural over chemically-treated products, cedar is a good choice. However, cedar is not as versatile or and will not last as long as pressure-treated wood. Even with direct ground contact, pressure-treated wood is expected to last at least 25 years, while cedar might need replacing after just a few.

Advantages and Disadvantages of Pressure-Treated Lumber

• High grades of pressure-treated lumber are just as insect and rot resistant as cedar, but are about half the price. They can be used in a variety of outdoor projects, so buying large quantities can be a good investment, unlike cedar -- which can only be used for certain applications and never for structural supports. However, pressure-treated lumber is a chemical product and has been known to make users ill. You must wear protective gloves and a dust mask while working with these products. The compounds used in pressure-treated lumber have also changed over the years due to health concerns. Arsenic compounds used in pressure-treated wood were banned in 2004, leaving alkaline copper quaternary (ACQ) and copper boron azole (CBA) as the most common chemicals.