Plywood is one of the most popular construction materials. You can see how widely-used it is just by strolling through home renovation stores or looking at construction sites. Simply put, plywood is multiple layers of strong thin boards bound together using a glue adhesive. It's an extremely common material in renovations or projects because of its versatility and quality.
The wood gets a grade on a scale of A to D, which correlates to its treatment and appearance. When plywood gets an A grade, it means the wood has no knotholes and is visually perfect. On the other end of the spectrum, when the plywood has a D grade, it means that it has many knotholes and isn't of very good quality.
When it comes to CD plywood, there is a C grade applied to one side of the plywood, and a D grade applied to the reverse side. You might think giving two grades is impossible since it's one piece of wood. However, since plywood is two or more sheets of wood pressed and glued together this allows it to have more than one grade. What usually causes confusion is when the "X" appears because this isn't a letter used in the grading system of plywood.
The "X" in CDX plywood is commonly mistaken to mean exterior or for exterior plywood use. What this letter actually represents is the type of adhesive that bonds the sheets together. The type of glue used is an exterior glue, making this grade of plywood more versatile and also the most commonly used.
CDX plywood is an exposure plywood. This means that it can come into contact with moisture, and it will not compromise the integrity of the wood. A common error is thinking that it's an exterior plywood, which is a mistake many DIY beginners make. Since CDX plywood can withstand certain conditions and is visually unappealing, it's useful in projects such as wall sheathing and flooring.
CDX Plywood Uses and Limitations
Locations such as laundry room floors or bathroom walls are great places to use CDX plywood. These areas are at risk of becoming very humid or damp, which makes this moisture resistant plywood a great option in most construction projects. Since the plywood is water resistant, its useful in any location that may have water exposure, but keep in mind that it's not waterproof. One of CDX plywood's characteristics is water retention when it comes into contact with harsh elements like rain. Once the plywood dries, it may end up warped due to the elements.
Keep in mind that CDX plywood has many uses. Many smaller DIY projects can use CDX plywood as long as appearance isn't a primary concern. This plywood is also useful to make small storage boxes or even shelves in a garage. To give the project a better appearance, a coat of paint may be necessary, if the end product looks poor due to the low grade of the plywood.