The subfloor is the layer placed on top of the joists, and its main function is to create a flat surface that flooring can go over. You can use different materials for subflooring, such as plywood, oriented strand board (OSB), concrete, composite materials, and wooden planks.
In this article, we’ll compare plywood subflooring to oriented strand board (OSB) subflooring to help you make an informed decision. These two are among the popular subflooring material choices for most users.
Plywood is a manufactured product made from combining thin sheets of wood veneer. To make plywood, manufacturers usually bond three or more layers of wood veneer together with an adhesive. Depending on the layers of veneer added to the plywood, you can get varying thicknesses from 1/8 inch to 3/4 inch.
As a subflooring material, plywood has been a standard since the 1950s. The standard thickness for plywood subflooring is usually between 1/2 inch to 3/4 inch. The spacing of your joists determines the best thickness of your plywood subflooring. However, thinner plywood can be used as underlayment before installing your desired flooring.
Apart from the thickness, plywood subflooring comes in standard plywood or tongue-and-groove sheets, also known as T and D. Standard plywood is good, but T and G plywood sheets are common and interlock for a smoother subfloor with no squeaking.
Oriented Board Subflooring (OSB)
Oriental Board subflooring, or OSB, is a popular substitute for plywood subflooring. OSB has also gained popularity over the years as a cheaper alternative to plywood subflooring. OSB combines wood chips with adhesives, which are compressed under high pressure.
Like plywood, combining wood chips and adhesives to make OSB creates a strong material that resists warping, deflection, and delamination. OSB also comes in standard shape or T and G for easier installation over joists. It also lacks knots and is relatively clean and flat when new.
OSB also comes in larger orientations or formats compared to plywood. While most plywood subflooring sheets come in 8 and 10-foot sizes, with OSB, you can get larger orientations of up to 16 feet and sometimes even higher. This makes OSB subflooring great where longer or wider panels need to be used.
Choosing Plywood vs. OSB Subflooring
Both plywood and OSB subflooring are relatively flat, and the layers of wood veneer or chips can be seen. For plywood, the wood veneer used can be used when viewed from the side. With OSB, the chips are clearly viewed from above.
When used as a subflooring material, the appearance of these two materials does not matter. This is because an underlayment and the flooring on top of it covers the subfloor.
Both plywood and OSB boards are installed in the same way. Each of this subflooring also comes in standard and T and G variants that can be easily fixed in place by even DIYers.
To hold the subflooring to the joists, most people use nails or screws. Plywood is better to nail or screw for a secure and stronger subfloor. While OSB is also nailed or screwed into place, it has less holding power, so you might use space fasteners more than you would with plywood.
When it comes to water resistance, plywood is the better choice compared to OSB boards. Plywood will absorb water faster than OSB but dry up faster and return to its shape. However, OSB is more resistant to water penetration. However, once it absorbs water, it retains it and will not shrink back to its normal shape.
While plywood shrinks back to its normal shape, prolonged exposure to moisture can cause it to delaminate. This reduces its structural integrity and may cause it to fail.
Both plywood and OSB subflooring have their exposure ratings. To prevent water from penetrating the subfloor, use a good underlayment and always wipe off standing water as soon as possible.
Strength & Durability
Both plywood and OSB are equal in strength and durability. However, plywood is more stiff compared to OSB, which gives it greater strength compared to OSB. Because of its stiffness, plywood is great under many different floorings, from heavier ceramic and stone tiles to lighter laminate and vinyl floorings.
OSB is a flexible material, so it lacks the stiffness of plywood. Although it is not great for heavier flooring, most flooring options can still be laid on OSB without any issues. However, floor movement can cause heavier flooring to crack or squeak.
For the price you pay for each subflooring, OSB subflooring is always cheaper. This makes it a budget-friendly option if you want to save or the cheaper option. Using OSB subflooring will significantly reduce the final cost of your new flooring installation or renovation.