Cedar, redwood, cypress, and hemlock are all types of wood that don't decay or rot quickly, and they can be expected to last anywhere from 10 to 20 years.
Cedar, with its natural resistance to decay, can also last up to 15 to 20 years if properly maintained. Recycled plastic timbers, on the other hand, can last upwards of 50 years, making them the most durable option among the three.
Cedar posts that are installed in a dry, well-drained area and are thick enough to resist warping can last for up to 25 years without rotting, while those installed in a damp environment may only last for 5-10 years before showing signs of rot.
You'll want to be vigilant about applying clear sealers with UV (ultraviolet light) blockers to keep the rich color of the natural wood. Don't put cedar where it's in direct contact with the ground or set it in concrete. It may last for a while, but eventually it will rot and deteriorate.
But despite the live trees living for over 1000 years, these anti-rot qualities mean a dead Red Cedar can take hundreds of years to decompose. Standing upright but void of their new growth these snags can stand for centuries before being downed by the elements.
A pressure treated fence post can generally last 10 to 25 years. Untreated cedar fence posts have decay protection because of their natural oils and compounds, but will usually last a few years less than their pressure treated counterparts.
The wood adds much-needed nutrients to the soil. The color and scent of cedar discourage some insects from hanging out in the yard. It repels moths, carpet beetles, cockroaches, termites, and certain kinds of ants, for example.
An untreated cedar fence can last anywhere from 15 to 30 years, depending on environmental conditions and maintenance efforts.
Selecting a wood species that is resistant to rot can really increase the longevity of a post in the ground. Wood species such as Osage orange, black locust, white oak, and various others are rot-resistant on their own.
The phenols, which give cedar its delightful earthy scent, are what repels fleas, moths, cockroaches, venomous snakes, mice and rats. And, in the laboratory, autoclaved cedar shavings have even been shown to inhibit the growth of micro-organisms.
Ventilation and Drainage
Picture gutters directing water away from cedar siding. These simple steps create an environment where rot struggles to gain a foothold.
Unlike pressure treated lumber, whose preservatives can break down eventually, leaving it vulnerable to decay and rot, cedar decking has a longer life expectancy. And if you take proper care of your cedar decking, it is likely to last much longer than its counterpart would.
Did you know you aren't suppose to put cedar in direct contact with concrete? To protect the post from rotting out, you can coat the bottom side of the post with Copper Naphthenate (only $7 a gallon!). Brushing or rolling on is an option but you get a much better coating if you can dip it.
Cedar, redwood, cypress, and hemlock are all types of wood that don't decay or rot quickly, and they can be expected to last anywhere from 10 to 20 years. Check which of these durable boards you can find locally sourced. My preference is always untreated cedar.
So Which Wood Type Lasts the Longest Outdoors? The general consensus is for hardwoods, such as ipe and teak. Since these species are extremely rot-resistant and durable, they have the best chance at a long life outdoors. These hardwoods are very durable and can last decades with minimal maintenance.
Properly finished and maintained, cedar will deliver decades of trouble-free service. If exposed for prolonged periods to conditions where decay could be a factor, such as where the wood is in contact with the ground, cedar should be treated with suitable wood preservatives. Wood is an excellent thermal insulator.
Pressure treated lumber is rated for 25 years ground contact. Other wood, that is not treated, if it stays wet for much of the year will rot in a few years. Regardless, you can dig a few inches below and put a layer of gravel and sand in so that you'll have a stable bed and so that water can drain away.
However, over time, the cedar is going to lose its natural oils. An antique cedar chest is going to be far less effective at repelling moths than a new chest.
Sealing cedar siding is not only important for protecting it from the elements but also for maintaining its rich natural color.
Cedar wood is naturally reddish in color, but over time, it will weather to a light gray if left untreated. This is due to exposure to the elements, such as rain, snow, sprinklers, and UV rays. The sun exposure dries up the natural oils in the wood, allowing water to penetrate and causing gray discoloration.
Clothing moths: Cedar's natural oils protect wool and silk garments from damage. Silverfish: Cedar is significantly repellent to silverfish—specifically the firebrat, effectively deterring them without toxicity. Certain beetles: Repels species that infest stored fabrics and carpets.
Cedar can and will rot and decay, it just takes alot longer than other wood. It can become weak and brittle so it depends on the design of your chairs and the thickness of the planks as to whether or not they'll hold up and support the weight you're going for.
Why is cedar the best? The heartwood is resistant to decay, making it especially desirable for service in contact with the ground. How long will it last? Cedar's natural resistance will give it a life expectancy of 15-20 years.