What are OSB and CDX and what is it used for? Often these questions are asked by owners.
Nowadays, engineering wood is increasingly being used. This engineering wood is made of real wood. But it is not solid wood. Both OSB and CDX are engineering wood products.
One should know their uses, advantages, and disadvantages before buying. In this blog, we will know what is the difference between OSB and CDX and whether it is suitable for your use or not.
OSB
Oriented strand board (OSB) is made of rectangular wood chips, resin, and waterproof adhesive by compressing into a sheet. Two types of glue are used in OSB Isocyanate glue for the inner core and Phenol-Formaldehyde (PF) for the outer layers.
There are four types of OSB. This type depends on their quality and use.
- OSB/1 – General-purpose boards suitable for indoor furniture.
- OSB/2 – Is a structural panel (Suitable for flooring, building panels, and crating)
- OSB/3 – Load-bearing boards (Suitable for damp or humid conditions)
- OSB/4 – Heavy-duty load-bearing boards for use in humid conditions suitable for outside sheathing, and composite load-bearing beams and floor trusses.
CDX
CDX plywood is made of multiple (5, 7, or 11 )thin veneer sheets of wood. which are glued on top of each other with high pressure. The name CDX defines itself. As C and D define the quality of the veneers. C grade sheet is used on the upper surface and D grade veneer sheet is used inside. let’s know this wood grade in more detail.
The grade of wood is divided on the basis of veneer quality. They are given grades A, B, C, D, and more. A grade wood is considered the top quality and D grade wood is considered as lower quality.
This means that medium and low-grade veneer sheets are used in CDX plywood. Whereas in CDX the letter “X” stands for exposure, which means the plywood can withstand a little moisture. It cannot withstand moisture for a long time.
But that doesn’t mean it’s weak. It has good strength because the veneer sheets are placed in opposite directions to each other.
CDX plywood is considered suitable for laundry rooms, bathrooms, and areas with mild humidity.
Difference between OSB and CDX
| # | OSB | CDX |
| Weight | 4′ x 8′ sheet of 1/2-inch OSB weighs around 54 lbs. | 4′ x 8′ sheet of 1/2-inch CDX weighs around 43 lbs. |
| Workability | Due to the excess of resin, there may be some problem with its cutting. It does not hold nails and screws well. | Generally very easy to work. CDX holds nails with glue well. |
| Availability | Its large panel is easily available. Its demand is very high all over America and other countries. | CDX does not come in a very large panel. |
| Water-Resistant | OSB performs better in moisture. | It does not perform well in moisture. |
| Price | 23/32″ thickness and 4×8 Sheet size cost about $13.37 | 23/32″ thickness 4×8 sheet size costs about $28.97 |
Uses | Sheathing in walls, flooring, and roof decking. | Exterior walls and roofs. |
Which one is Waterproof? OSB or CDX
OSB performs well in moisture. Because its resin and adhesive do not allow moisture to penetrate quickly. The second big reason is that it does not have any gaps and layers. But whenever it absorbs moisture, it changes its shape and takes more time to dry and go back to its original state.
If we talk about CDX, then it does not perform very well in humidity. Because it is made up of many thin layers. With these layers, moisture easily penetrates into the plywood. But CDX dries quickly and comes back to its original shape and size.
Treated CDX is considered better for moisture and it is resistant to termites, fungal decay, and rot. Treated CDX is slightly different from general CDX plywood. During the manufacturing, it is passed through special chemicals treatment. So that the properties of the plywood sheets are enhanced.
We know that nothing made of wood is 100% waterproof. Just treated plywoods perform well in wet places. So talk to your dealer about treated plywood.
OSB vs CDX: Which one is good for you?
OSB and CDX are both great products. Which one is good for you? It depends on your usage. OSB is great for some purposes whereas CDX is great for some purposes.
OSB is medium moisture resistant. It can withstand moisture for a short time. Therefore it is suitable for floor, wall, roof sheathing, and for other moist places.
CDX plywood is not good moisture resistant. But it is stronger and more durable than OSB. It is used for roof sheathing, construction of crates and boxes, garage shelves, sub-flooring, and low humidity. Due to the cross structure of CDX, it can easily withstand heavyweight.
OSB vs CDX Pros and Cons
OSB Pros and Cons
| Pros | Cons |
| OSB is stronger and denser. | OSB can be difficult to paint. |
| It is inexpensive than other regular hardwoods. | Does not hold nails and screws well. |
| OSB is manufactured in large, tall panels. | OSB absorbs less moisture and does not dry quickly. Swells with water |
| Versatile with many uses | Not for use with flooring |
CDX Pros and Cons
| Pros | Cons |
| CDX is easy to paint and polish. | CDX is not manufactured in large, tall panels. |
| Hold nails and screws well. | More expensive than OSB. |
| Can be used to finish work | CDX absorbs moisture but dries out faster and more completely |
| Can be used beneath flooring | Potentially not as durable |
Final words
If you still have confusion between OSB and CDX. Before making the final deal. Consult the dealer about your usage and choose the right product.
