We create pressure-treated lumber by processing wood to make it more durable. While some wood becomes resistant to insects, decay, and damage from moisture, pressure treatment also creates fire-resistant wood. You can choose from a variety of different types of pressure-treated wood depending on your type of project.
Alternatives to pressure-treated wood come in handy when you need wood without the harmful chemicals that this type of wood contains. Pressure-treated wood is not a universal solution, as it has its limitations. The ideal alternative to pressure-treated wood is to use woods like cedar or redwood that contain natural preservatives.
Pressure-treated wood is not a one-size-fits-all type of solution. It has its limitations. For example, this type of wood cannot prevent damage from direct sunlight or damage due to excessive moisture. Moreover, pressure-treated wood contains harmful chemicals that can contaminate the soil if the wood contacts it directly.
Changing the chemical from copper chromated arsenate (CCA) to alkaline copper quat (ACQ) or copper azole (CBA-A) can reduce the toxicity of pressure-treated wood. This is especially vital if you use wood that will come into contact with the soil where edible crops grow.
Since 2004, strict legislation came into existence regarding the use of CCA for pressure treating wood. Therefore, any pressure-treated wood that dates before 2004 has every likelihood of containing CCA, since there was no regulation in place before that year.
Advantages of Pressure-treated Wood
Outdoor structures like fences, decks, wooden gates, and posts tend to crack, decay and warp due to exposure to the elements. Insects add to the damage. Pressure-treated lumber will prevent such damage to a great extent.
If direct or indirect contact with humans and animals is minimal, pressure-treated wood is an excellent solution for the longevity of many types of wood.
Disadvantages of Pressure-treated Wood
Even pressure-treated wood lacks the durability of even some types of hardy natural wood. Excessive moisture continues to be an issue. It can result in the formation of bacteria, fungi, and other microorganisms causing damage to the wood. Damage from insects can also cause the wood to deteriorate.
Other limitations include susceptibility to damage from excessive exposure to sunlight and being exposed to extreme climates. But the main issue with pressure-treated wood is the chemicals that it contains.
Moreover, you may face some aesthetic issues with pressure-treated wood. For example, when you use it for outdoor applications like fences, fence posts, decks, and gazebos, it tends to splinter. This typically occurs with cycles of frequent drying and wetting, like when you leave the wood exposed to extreme climates.
If pressure-treated wood remains outside for over six months, it might not only split but could exhibit stains from fallen leaves and mud spatter at the ground level. A common practice is to add a stain and penetrating sealer to offer some degree of protection.
Alternatives to Pressure-treated Wood
Considering the drawbacks of pressure-treated wood, despite some clear advantages, scientists developed alternatives. They come under the category of what we commonly call “modified wood.” This category of wood is still natural but aims at eliminating the downsides of pressure-treated wood.
Kebony is the trade name for a natural wood product. It is treated to prevent warping, rot, and pests. It has a fair degree of dimensional stability and we consider it maintenance-free.
The manufacturing process involves permanently altering the cell structure through a process called “Furfurylation.” It involves two stages. First, they inject plant-based alcohol (furfuryl) into the sapwood. Then, the wood goes into a kiln for curing. The result is the polymerization of the wood cells and furfuryl.
The polymerization results in a thickening of the cell walls of the wood. It makes the wood more durable. The manufacturer of this product offers a 30-year warranty if the wood isn’t in direct contact with the ground.
Kebony exhibits a hardness equivalent to hard maple, which is approximately doubly harder than Ipe. Further, the heat caramelizes the sugars in the wood, which makes the wood darker.
The woods that are used to make Kebony are usually radiata pine from trees that grow on the Central Coast of the United States and Mexico. We use it for roofing, cladding, decking, general construction, and applications where precision and appearance are paramount.
Lignia is another high-performance modified timber in North America. The country of origin for this product is the United Kingdom. You can get different grades of this pressure-treated wood alternative to suit its application. A few examples are fire-resistant, marine, and standard grades.
The process of manufacturing Lignia involves treating the wood with a low-emission chemical. The result is that it becomes harder and more dimensionally stable. The procedure involves impregnating the wood with a resin under high pressure. The resin penetrates the wood up to the core, enhancing its performance. As with other modified timber, Lignia also becomes extra-durable, harder, denser, and dimensionally more stable.
But the manufacturer also claims protection against fungal decay and rot for 50 years if the wood is above the ground. Lignia makes good decks, wooden floors, and cladding and serves a variety of other applications.
Thermally Modified Lumber
Thermally modified” or “heat-treated” lumber involves using heat at steam to modify the cellular structure of the wood using no chemicals. The heat treatment involves heating the wood to about 400°F (204°C).
The result is that the wood’s cell structure changes, and the moisture and sugar content decreases. Since water and sugar are the two things molds and fungi feed on, the wood becomes more resistant to decay. Another result of the heat process is that the wood becomes an exotic brown, transforming into a delightful silvery gray as the wood ages.
We use wood species like ash, spruce, and pine to manufacture thermally modified lumber. The ash lumber that makes this wood comes from managed sustainable forests. Its hardness rating is similar to that of oak.
Thermally modified lumber is relatively maintenance-free. However, staining the wood and applying a finish can enhance its life and help prevent surface cracks by stabilizing the wood. Staining it can preserve the darker tones. But you will see a certain amount of graying of the wood as it ages.
The concept of thermally modified lumber is relatively new to the United States, although it is gradually entering the mainstream market. However, it has been used in Scandinavia and parts of Europe for over 70 years and about 20 years in Japan.
Non-wood Alternatives to Wood
Whether it is natural or pressure-treated wood, the source is natural wood. Many non-wood alternatives may last longer than many types of wood. The advantages are many, the primary one being cost.
You can make a fence using galvanized welded wire, which will be more economical and durable. Although it may lack the natural beauty of wood, it will serve its purpose.
Alternatively, vinyl is entering the market as a viable wood substitute. It is cheap, lightweight, and durable and you can make it resemble natural wood. But it lacks the rustic charm of natural wood.
Our forests are fast depleting and some wood species have all but become extinct. Governments of some countries are making efforts to protect their green resources, while others are not doing enough. We all need to show some responsibility and reduce our carbon footprint.
We can reduce it by using alternatives to solid wood like pressure-treated wood, which is a more sustainable solution. Alternatives to pressure-treated wood are even more sustainable, and cost-effective but durable. So, consider using the materials mentioned here in your next woodworking project to make your contribution to the environment.