The Plywood Advantage

Travis Gapp

May 6, 2023

My dear readers, let us talk about the importance of quality building materials. As a builder who has spent my entire adult life crafting beautiful and functional structures, I can attest to the fact that the materials you use will make or break your project.

Many builders opt for the cheapest materials available, and while I understand the allure of a lower price point, I must urge you to reconsider. The use of higher quality materials may cost more upfront, but they will pay dividends in the long run.

Take, for example, the sheathing of roofs. Some builders will use oriented strand board (OSB), a composite wood product made from wood strands glued together with resin. While OSB is cheaper than plywood, it is an inferior product for wet climates. Not all OSB materials are the same though, some have sealers to help resist moisture (i.e., tongue and groove sub-floor).

Plywood, on the other hand, is made by slicing thin layers of wood from a log and gluing them together with the grain of each layer perpendicular to the one beneath it. This creates a strong, stable sheet that is perfect for sheathing roofs. Due to how it is made, plywood retains more of its natural tree-like structure, and thus water moves through it more easily.

Plywood is superior to OSB in a number of ways. Firstly, plywood is more resistant to moisture than OSB, which can swell and become damaged when exposed to water. This makes plywood a better choice for sheathing in areas with high humidity or frequent rainfall. To illustrate this, the Pacific Northwest is a region that can stay damp and see dozens of inches of rain over many months on end. This type of climate can degrade OSB at an accelerated rate.

In my professional experience, leaving a raw sheet of OSB outside in the rain for just one month renders it unusable. A single downpour can cause it to swell to the point of never returning to its original thickness, although it may still be usable. In contrast, I have installed plywood that has endured years of exposure to the weather. While plywood also swells and shrinks, it is much more stable than OSB.

Additionally, plywood is more structurally sound than OSB. Plywood is less likely to split or crack when fasteners are driven into it, which means that it will provide a stronger, more secure base for your roofing and siding. OSB does beat plywood when it comes to shear strength, but only when they are both undamaged. Damaged or rotten plywood holds better in punch through resistance, lifting or tearing off from a fastener, and shear when compared to OSB exposed to water for the same period of time. If a home is located under fir trees that can drop heavy-ended limbs like giant spears during winter storms, going with a thicker plywood on the roof could be the difference in a limb making it into the living space. The bottom line is plywood resists water intrusion better than OSB and is better as an all around roof sheathing option.

Finally, plywood has a more attractive appearance than OSB. Plywood has a natural wood grain that can be stained or painted to match your desired aesthetic, while OSB has a uniform, industrial look that is difficult to disguise. When building with open soffits where the roof sheathing is visible, plywood is a must.

But why stop at plywood? Consider using higher quality materials in all aspects of your building projects. Quality materials will not only improve the appearance and durability of your structures, but they will also increase the value of your property.

In conclusion, my dear readers, do not be swayed by the siren song of low-cost building materials. Choose quality materials that will provide a solid foundation for your projects and stand the test of time. And when it comes to sheathing your roofs for any size project, remember that plywood is always the superior choice over OSB.