Picking the right type of wood for home building projects is absolutely essential, as the type of wood can impact performance, durability, and long-term maintenance to be expected. Different types of wood can offer different pros and cons, and while CDX plywood may be the best pick for one DIY project, it may not hold up for other home construction tasks. Whether you’re building a small bookcase or backing exterior siding, the type of home construction project will make a big difference as to whether or not CDX plywood is fit for the job at hand.
How Is CDX Plywood Made?
CDX plywood can tell you a lot about how it is made simply in its name. The ‘CDX’ is actually a combination of ratings that provide information as to the quality and construction of the plywood.
The quality of wood can be evaluated based on knots, splinters, color, durability, and more. These features are assessed and then assigned a rating – either A, B, C, or D. Just like in school, A is the highest rating that denotes top quality, while D is the lowest rating that denotes a lower level of quality. Plywood sheets that rank A or B tend to be the most expensive pieces, whereas C-level and D-level plywood pieces are more affordable and cheaper in quality, making it a more economical option.
The ‘X’ in CDX plywood refers to the way in which the different layers of plywood veneers are glued together. Depending on the quality of glue used, the plywood will be more or less susceptible to damage due to exposure. When it comes to CDX plywood, the ‘X’ signifies exposure, which means that while CDX plywood is slightly water-resistant, it is not waterproof, and therefore the CDX plywood can only withstand a limited amount of moisture over a short period of time before showing signs of degradation.
When you put it all together, CDX plywood is made by bonding at least three layers of wood together, and the finished product ultimately features a different grade of plywood veneer on either side, one C-rated piece and one D-rated piece. Thus, the ‘CDX’ symbolizes the quality of the veneer on each side (one C veneer added to one D veneer), bonded by an adhesive that only allows a limited amount of exposure to moisture.
During the CDX plywood adhesive process, manufacturers carefully position the wood grain elements of the plywood so that they are aligned in a way that reduces shrinkage. Sometimes, a lower quality wood is used for interior layers, reserving the better layers for the outside. Nonetheless, CDX plywood ranks as a convenient and affordable sheet of wood composed of several layers. When you think about it, this single piece of CDX plywood actually has a lot of elements to consider!
What Is CDX Plywood Used For?
While the classification of CDX plywood may seem like it is not a very durable option, CDX plywood is actually a perfectly suitable choice for a lot of home building projects, both inside and outside of the home!
Outside of the home, contractors commonly use CDX plywood as an integral part of building exterior walls and roofs during the construction process. Granted, CDX plywood is never used as the final exterior layer, because of its lack of durability. Instead, it is typically used as added support underneath shingles, beneath roofing felt, and behind insulation and siding.
Inside of the home, CDX plywood is often used as an additional flooring layer that rests just below the carpet pad or as a backer board for tiling. In addition to these structural uses, CDX plywood is also commonly used for minor utility purposes, such as rudimentary shelving in basements, storage cabinets, or sheds. However, because of its low-quality exterior, CDX plywood is not often used for pieces of furniture that require a more finished appearance inside the home.
How Long Can CDX Plywood Be Exposed?
Homeowners considering using CDX plywood for their next project should recognize that, by no means is CDX plywood fit for extensive exposure to the elements, because it is not weatherproof. Rain and snow can serve as a serious threat to the integrity of a structure made with CDX plywood. With that said, CDX plywood is capable of withstanding limited exposure to moisture – including rain and snow.
But it should be emphasized that ‘minimal’ is the key word here. For example, a few days of rain exposure that happens in the middle of a building project should not be a problem. After all, because of the composition of wood grain that is used during CDX plywood production, this type of plywood is able to absorb moisture at a certain level without warping, splitting, or rotting. Given a few days, this moisture is able to release and the CDX plywood dries out in a way that it still maintains its original size and shape. However, if a building project drags on and the CDX plywood experiences repeated assaults of rain and snow, say over the course of the winter, then this can pose a severe problem for the building project.
In general, CDX plywood should not be left as the first line of defense against heavy moisture on the exterior part of a building, especially over an extended period of time. However, when used on the interior, such as in a bathroom, laundry area, or another room that experiences frequent humidity, the composition of CDX plywood should be able to hold up reliably.
What Is CDX Treated Plywood?
Plywood in general – and especially CDX plywood – is known for being susceptible to damage from everyday elements. That is why manufacturers have come up with a solution that reinforces the integrity of CDX plywood to make it better fit for holding up against rain, snow, humidity, and mold. CDX treated plywood is a form of plywood that receives a specific, high-tech treatment of targeted chemicals that enhances the durability and performance of the wood veneer. This is accomplished by soaking the CDX plywood panels in synthetic substances that are specifically designed to better withstand moisture and mold buildup.
Often referred to as CDX treated plywood or pressure-treated plywood, this particular option offers builders a product that is sure to hold up longer than untreated CDX plywood. This matters because increased durability extends the life of CDX plywood, which means that homeowners will have to deal with less maintenance, like repainting or replacing CDX plywood panels. And as most homeowners know, continually repainting, staining, or replacing segments of full sheets of CDX plywood panels can be a pain. Anything that can prolong the performance and longevity of a product is a big plus when it comes to home ownership and maintenance, so CDX plywood that has been treated with extra protective qualities is a popular choice.
CDX Plywood vs OSB
If you are new to working with plywood, it is easy to get some of the options mixed up. For example, many first-time homeowners confuse CDX plywood with OSB plywood. But the truth is that, even though both OSB and CDX plywood are commonly used in a single home construction site, there is a big difference between these two plywood types!
OSB which stands for oriented strand board, is composed of wood chips bonded together with resin and glue. While this may sound similar to CDX plywood, it is a very different composition process, and OSB board is generally much less durable than CDX plywood. Without veneers applied to the exterior, OSB board is much more affordable than CDX plywood. In addition, the resin and glue bonding approach actually makes OSB board better suited for enduring moisture, unlike CDX plywood which can become warped when moisture builds up between the bonded layers.
Because of these differences, OSB is generally the better choice for exterior roofing projects and shingle foundations. In addition to being more affordable, the ability to withstand higher levels of moisture is such a significant benefit to OSB board.
CDX Plywood Sizes, Thickness, & Availability
If you are set on using CDX plywood for your next home building project, then it is time to explore the options available in terms of size, thickness, and availability. The good news is that CDX plywood is available at most home and garden stores, since it is a common material used for home DIY and construction projects. CDX plywood sizes are typically available in sizes 3, 5, 7, and 9, and there are a variety of thicknesses available, ranging from 1/4 inch to 1 1/4 inch thickness. In addition, 3/8, 1/2, 5/8, and 3/4 thicknesses are usually available at most stores, too. When considering CDX plywood thicknesses, remember that these are nominal sizes, and you should account for a deduction of about 1/32 inches after sanding, which most projects will require.
Determining if it’s Right for You
As you can see, CDX plywood offers a lot of pros and cons. Be sure to consider the specific needs of your project to determine if CDX plywood is fit for the task at hand. Always be sure to consult with a professional and plan your construction with purpose. CDX plywood is an excellent resource for homeowners and contractors who are looking for an affordable, durable sheathing solution.