Selecting the right subfloor material is an important decision when building or renovating your home. The two most common options for subfloors are oriented strand board (OSB) and plywood. Both have their advantages and disadvantages when used as a subfloor, so it’s important to understand the key differences between them.
Cost Comparison Between OSB and Plywood
One of the biggest considerations when choosing a subfloor is cost. OSB is generally cheaper than the same thickness of plywood. Here’s a quick cost comparison:
- A 4×8 sheet of 7/16″ OSB typically costs $15-20, while a sheet of 5/8″ plywood costs $25-35.
- A 4×8 sheet of 3/4″ OSB runs $20-25, while 3/4″ plywood is $30-45.
So OSB provides a significant cost savings, especially for large areas. The cost difference does fluctuate based on current wood prices though.
Strength and Durability
Plywood has long been considered the stronger and more durable subfloor option, but improvements in manufacturing have helped strengthen OSB:
- OSB is made from small wood strands glued and pressed together. The random strand arrangement provides strength in all directions.
- Plywood uses larger wood veneers layered in alternating grains, providing exceptional strength for its thickness.
Both will perform well as subfloors when installed properly. OSB meets building code requirements for structural rigidity, though plywood retains a slight edge in durability over the long term.
Moisture Resistance
Plywood historically has better moisture resistance than OSB, but again OSB has improved:
- Plywood uses high-grade adhesives that firmly bond layers even when exposed to moisture. This helps minimize swelling and delamination.
- Modern OSB also utilizes moisture resistant adhesives and resins to reduce water absorption. Look for boards rated as Exposure 1 for best moisture protection.
For subfloors, either OSB or plywood properly sealed and installed will provide sufficient moisture and water protection.
Ease of Installation
OSB and plywood are installed in similar ways as subflooring:
- They are both fastened to joists using nails or screws spaced 6-12 inches apart around the perimeter and through the field.
- Seams should be offset from the underlying joists and spaced 1/8 inch apart.
- 4×8 sheets of OSB may be slightly easier for one person to maneuver and install compared to full plywood sheets.
Overall, there is little difference in difficulty of installation between the two. Both require proper gapping, fastening, and seams offset from joists.
Workability for Finished Flooring
OSB and plywood can both provide a smooth, stable foundation for installing finished flooring:
- Plywood’s smooth veneered surface requires little prep work for flooring installation. OSB may need sanding at seams or high spots.
- Countersink any protruding fasteners and fill large gaps in either subfloor to create an even surface.
- Always follow the flooring manufacturer’s recommendations for acceptable subfloor materials. Many will specify a minimum thickness for OSB or plywood.
With proper prep work to flatten the surface, both offer suitable subfloor foundations for finished flooring.
Sound Insulation Ability
When it comes to dampening sound transfer in a room, plywood is generally better than OSB:
- Plywood’s layered construction does a superior job blocking impact noise and containing sound transmission, especially thicker 5/8″ or 3/4″ sheets.
- OSB is more likely to transmit noise through the subfloor from footsteps, voices, or objects dropping. The gaps between strands don’t isolate sound as effectively.
If sound insulation is a major concern, plywood may be worth the additional investment over OSB for less noise transfer through the subfloor.
Environmental Impact
Homebuilders and consumers alike are becoming more concerned about the environmental impacts of their material choices. Here’s how OSB and plywood compare:
- Most OSB sold today contains at least 50% recycled wood content from wood waste products. The adhesives used are largely formaldehyde-free as well.
- Plywood also utilizes recycled wood fibers in its core veneers. It contains fewer chemicals overall than OSB.
Both products are manufactured predominately from fast-growing, responsibly harvested wood. Overall, plywood may have a slight environmental edge but OSB is catching up.
OSB vs. Plywood: Best Subfloor Material Compared
When choosing between oriented strand board (OSB) and plywood for your subfloor, there’s no universally “best” option. Consider factors like your budget, the look you want to achieve, moisture concerns, sound insulation needs and environmental impact. For many homeowners, OSB provides the most cost-effective subfloor solution that meets structural and installation requirements. Plywood offers added durability, noise insulation and surface smoothness at a higher cost. Ensure proper installation and moisture protection with either material, and your subfloor will provide a solid foundation for years to come.
Frequently Asked Questions About OSB vs. Plywood Subfloors
Which is better as a subfloor – OSB or plywood?
Both OSB and plywood make excellent, code-approved subfloor materials. Plywood is stronger and better at dampening sound, but more expensive. OSB is affordable and has improved in strength and moisture resistance. For subfloors, OSB provides good performance at a lower cost in most cases.
Can you use OSB for subfloor instead of plywood?
Yes, OSB is an approved material for subflooring in home construction. It meets structural rigidity requirements when installed correctly using the proper thickness and fastener schedule. Many builders now default to OSB as their subfloor instead of plywood due to cost savings.
What thickness of OSB should be used for subfloor?
Most subfloor OSB is either 7/16”, 15/32” or 3/4” thick. The required thickness depends on the floor joist spacing in new construction. For 16” on-center joists, code requires at least 15/32” OSB. For joists 24” on-center, OSB subfloor should be at least 23/32” thick.
Is OSB stronger than plywood?
Plywood is still slightly stronger than OSB overall when comparing the same thicknesses. This is due to plywood’s cross-laminated veneer layers which provide excellent strength, rigidity and resistance to delamination. But modern OSB manufacturing has closed the gap significantly through use of waterproof resins and pressed wood strands.
Does OSB hold up as well as plywood?
When installed properly on a flat, stable foundation, OSB can be very durable as a subfloor. It may not have quite the long-term dimensional stability of plywood, but its rigid pressed construction enables it to hold up well over time. Regular foot traffic and normal wear-and-tear should not be an issue.
Can you screw down wood floors over OSB subfloor?
Yes, OSB provides a suitable surface for fastening hardwood flooring. Use the proper length wood flooring screws to attach boards through the hardwood and subfloor into the joists. Make sure to countersink any protruding fasteners and flatten any raised edges for a smooth surface.
Does OSB need to be sealed before tiling?
Sealing an OSB subfloor prior to tile installation is highly recommended. An underlayment and membrane should be applied to protect against moisture damage. Fiber-reinforced cement board is also an excellent underlayment for durability and water protection when tiling onto an OSB subfloor.
Can OSB get wet during construction?
OSB swells and loses structural integrity when soaked repeatedly. Avoid excessive moisture exposure during construction. Cover and protect OSB subflooring to keep it dry until roofing and exterior cladding is complete. Replace any warped or compromised OSB boards prior to finishing the floors.
Conclusion
When it comes to subflooring materials, both OSB and plywood have benefits that make them suitable choices in the right situation. OSB is the more budget-friendly option that still provides adequate strength and performance for most homes. Plywood offers superior durability, noise insulation and surface smoothness that may justify its higher cost in some premium installations. Proper installation and moisture protection are critical for success with either. Consider factors like cost, sound transmission, flooring materials planned, and overall performance needs when deciding between OSB and plywood for your next subfloor project.