CDX plywood is an inexpensive WBP plywood using low grade veneer face. It is popular in North American and Latin American countries.
CDX literally means C face and D back with Exposure grade glue. In practice, both face and back veneer are D grade with large knots. The knots on faces don’t affect the panel quality because CDX plywood are non-appearance plywood that are used in invisible places.
D Grade Faces With Large Knots
CDX plywood has a good core to achieve performance. But it is manufactured with low grade face veneers such as C/D grade pine.
CDX is a term that is popular in consumers but it doesn’t require a C grade face at all. In practice, the face veneers are usually D/D grade pine. Meaning both face and back are D grade pine veneers.
“X” Means Exposure Glue
The letter “X” represents exposure, which means the CDX plywood can be exposed to moisture for some time. But not too long. This feature makes CDX plywood similar with WBP plywood but not as good as the best WBP plywood.
CDX Plywood vs. OSB
CDX and OSB are used for very similar things. CDX is best for sub-flooring where it does not get in contact with a lot of moisture. It is also used for roof sheathing. Below are the major differences between CDX plywood and OSB.
Resistance to water
CDX can be exposed to moisture for a limited time. While OSB 3 can be exposed to humid conditions for very long time.
CDX plywood is not waterproof and it absorb water. But it lose water quickly and restore to its original shape.
OSB doesn’t absorb water easily. But when it does, OSB doesn’t lose water in a short time.
OSB price was cheaper before the covid-19 pandemic.
But now, OSB price is higher than CDX plywood.
CDX Plywood Uses
- Sub-flooring: Classic non-appearance occasions where strong and cheap CDX plywood is used. T&G CDX plywood available.
- Roofing: One of the most common exterior uses of CDX. CDX plywood is strong and water-resistant. So it is good for exterior use like this. Even if the CDX plywood surface gets wet, it can dry quickly.
- Sheathing: structural use.
- Bracing: structural use.
- Packaging: Where knots on the packaging boxes are not a problem.
CDX plywood are used when appearance of plywood is not important.
CDX plywood can be considered a light WBP plywood.
Usually pine face with mixed core.
CDX plywood is now cheaper than OSB.