A common question in industrial carpentry is whether to use OSB or plywood as the preferred panel material. Both are widely available and both can be used in ISPM 15 compliant crates for international shipment. Both are easy to work with and look presentable. Which one to choose?
It is first important to understand what the differences between OSB and plywood are. OSB is made of compressed and glued together wood strips, aligned to achieve particular strength characteristics. Plywood is made from thin layers of wood glued together, with the grain in each layer alternating direction. Each type can be made to a variety of ASTM standards and grades, in addition to specialty industry standards. There are strong and weak varieties of both types. Plywood, however, will always have the highest visual appeal.
What about performance? Cheap OSB is weaker than cheap plywood and more vulnerable to water exposure. OSB sheathing is often called “vertical mulch” for a reason. However, high end OSB outperforms almost all plywood in every respect. Better flatness. Higher tolerance of wet and dry cycles. Much stronger. However, all of this comes at a cost. Further these high performance sheets are difficult to find in some areas as they are only used by high-end home builders. Your typical big box retail supplier is not going to have much available in this type. OSB in a Home Depot is the cheap stuff for the most part. When buying from the average supplier, the high end in strength and performance is exterior plywood.
Assembly is different for OSB and plywood. Generally, OSB used in crates tends to be the cheaper type and has certain issues. Nails and staples work almost as well as in plywood. Screws, however, do not work well as the screw action tends to tear the OSB apart. Similarly the edges of OSB are more fragile than the edges of plywood. Exposed OSB edges will likely be visibly damaged if hit whereas plywood will typically remain undamaged unless subject to outright abuse. For this reason OSB is a poor choice for reusable crates.
How much does cheap OSB save over plywood? This is mostly a question of quantity. OSB can be cheap, less than ten dollars a board. However, if you are only making a small number of crates the overhead and labor costs will make the cost increase trivial. In large crate volumes, a $20 per sheet difference in price makes a significant difference to the overall cost.
The natural question then becomes how do you choose between the two for your crating needs. For under 5 crates, plywood should be the choice. If there is any doubt, plywood should be the choice as it is much more commonly used in ASTM standards. You see very little OSB crates “in the wild.” For high volume orders where you really are sure that OSB will meet your requirements, OSB can be chosen.