Roof decking is the layer between your metal roofing panels and the structural elements of your roof. This component is essential in both metal roofing and traditional asphalt shingle roofing. If you’re a contractor, this is no news to you. In the process of constructing a roof, there are typically two different roof decking materials. The contractor can choose an oriented standard board (OSB) or plywood to create the decking of the roof. Each material has its similarities and differences. Here are some things to consider when choosing your decking material to install on a roof.
How it’s made—Plywood vs. OSB
These sheets of wood may look similar, but they are not created the same. Plywood is created by taking extremely thin sheets of wood—called plies— and gluing them together. The thickness of the plywood can be controlled by the number of plies glued together. Oriented standard board (OSB) is created much differently. If you take a look at a sheet of OSB, you’ll notice the surface isn’t extremely smooth. This is because OSB is created by taking woodchips, gluing them together, and hot-pressing them down. This process takes the original wood chips and condenses them into solid sheets. The thickness of OSB is controlled the same way plywood is. The more wood chips there are, the thicker the OSB will be.
Popularity—which is used more?
Originally, plywood was the go-to choice for roof decking. The material is strong, durable, and tested over time. The only downfall when comparing the two materials is cost. Although plywood is traditionally used to create the roof deck, it’s becoming more popular for contractors to use OSB. OSB is incredibly more cost-efficient than plywood. Customers are choosing OSB to be installed as their roof decking because it can lower the cost of their overall roof installation. Not all decking is the same. Always pay attention to the thickness of the boards, and work accordingly with your materials.
Comparing plywood and OSB
There are characteristic differences between the two materials. Just because OSB is cheaper, doesn’t necessarily mean it lacks in quality. OSB is heavier than plywood, and it’s typically stronger as well. The one characteristic that OSB lacks compared to plywood is water retention. The dense woodchips compressed together will take longer to dry if they become wet. Plywood is less likely to take as long to dry in these circumstances.
A roof that leaks isn’t doing its intended job. You never want your decking to become wet in any circumstances. You never know what Mother Nature will bring to the Midwest, so it’s extremely important to make sure your decking material is completely dry at all costs! Some roof problems could stem from panels installed over wet decking. Over time, plywood has shown experience to dry much quicker than OSB. When OSB gets wet, it will swell over time. Not only will it swell, but the wood chips will also break away. Of course, you don’t want either of these decking materials to become saturated. It usually isn’t an issue if they get slightly wet from rain—when given the correct amount of time to dry.
Installation
Both forms of roof decking are installed the same. The only thing different is the choice of thickness you use with each. The thicker the material is, the less likely the nails will pull out of the panels. Metal roofing is quite durable, and panels hardly lift. However, no roof is 100% perfect! This typically happens when there are strong winds and other weather conditions. This usually isn’t a fault in the roof and decking installation. All homes can take quite the beating over the years by Mother Nature!
What roof decking material will you choose?
After hearing the pros and cons of each material, would you use plywood or OSB for your decking? Cost, durability, and composition are all varying elements in each material. No matter what you choose, both materials are top of the line and complete the job!