Plywood vs OSB: Which Subfloor is Better

A normal wood-framed flooring system is more complex than you could ever think. Apart from the visible materials such as hardwood, tile, or carpet, there is underlayment. Below it is a subfloor that operates as the foundation and offers structural reinforcement to the floor. 

Builders debate whether OSB vs. plywood building materials are the best structural panels for subfloor.

Plywood is the most common material and is made from multiple plies of thin sheets of wood oriented in opposite directions for structural integrity. Plywood is recognized because of its strength but costs more than OSB.

Oriented Strand Board (OSB) is a manufactured structural panel consisting of strands of wood stacked, glued, and then undergoing a hot press to bind the wood strands into large sheets. OSB boards are more prevalent in the construction industry today because they cost less than plywood and meet building code requirements.

How Thick Does Plywood Need to Be f...
How Thick Does Plywood Need to Be for a Floor?

Let’s look at the features of the two below:

Plywood SubfloorOSB Subfloor
Strength of the structureMore rigid and strongerIt’s slightly weaker
Resistance to moistureIt doesn’t swell when wet It edges and swells when wet
Suitability of Flooring MaterialsIdeal subfloor for all flooringAvoid stone and ceramic
Cost or priceIt costs about 20% more—currently, about $50 to $70 per 4′ x 8′ sheet depending on thickness.More economical than plywood. Cost $35 to $45 per 4′ x 8′ sheet depending on thickness
Screw/Nail Holding PowerHas a better holding powerHas less holding power
Installation DetailsScrews and nails are driven through the field and along the seamsScrews and nails through the field and along the seams; Might need more fasteners
SizesHas either 4′ x 8′ or 4′ x 12′ sheetsContains either 4′ x 8′ or 4′ x 12′ sheets

Which is better between these two materials? This article will explore some of the features and differences between the two materials. 

What Is Better: OSB vs. Plywood?

Plywood and OSB have varying factors that make them different from one another.

A plywood subfloor uses 3/4 inch, 5/8 inch, and 1/2 inch thick sheets with one smooth side facing up and one rough side facing down. The size of the sheets is 4′ x 12′ feet or 4′ x 8′ feet, with 4′ x 8′ as the most commonly used in the subfloor because it’s easier to work with. 

CDX plywood is created by gluing multiple thin layers of wood at 90 degrees and then pressing them together to create a strong structural sheet. In the 1950s, plywood replaced solid wood as the most common subfloor material in homes. 

OSB manufacturers use large wood strands of new growth wood from fast-growing trees to make their OSB products. Wood fiber strands from smaller trees are arranged up to 50 layers, and about 6 inches thick before the hot press occurs. The manufacturing process includes adding a hot bonding glue tightly compressed into wood sheets. 

OSB is more uniform than plywood. It’s cheaper than plywood since it’s created from leftover wood materials. OSB started being applied as subfloor materials in the 1970s. 

Wall sheathing is attached to the exterior walls of all houses. Both plywood and OSB are also used as exterior sheathing. Plywood sheathing replaced shiplap wood that was once used in older houses. OSB sheathing is now used in about three-quarters of new home construction today.

Now let’s explore the differences between plywood and OSB in different areas:

Appearance

Plywood is created from different layers of wood veneer that are glued together at 90 degrees. The layers will be visible when you view the sheets from the edges. However, if you view it from the top, the veneer looks like solid wood. 

The OSB also has several flat wood chips glued together to form a solid sheet. The flat chips are visible when you view the sheet from the top. 

Here, we can conclude that the two materials tie, and there is no clear winner. 

Heat And Water Resistance

Plywood has more capacity for absorbing water but is also known to dry faster. It also boasts a higher resistance to permanent swelling. 

OSB has a lower resistance to both heat and water. It also absorbs moisture and holds it for longer. 

OSB contains some untreated edges that are more susceptible to swelling when wet. If there are severe flooding and spills, you should correct them as soon as possible. 

Under this category, plywood is the clear winner since it resists permanent swelling. However, both materials can burn if your house catches fire. 

Cleaning And Care

Both plywood and OSB are hidden materials. It means that there is no cleaning or care needed. 

However, you should expose the subfloor and ventilate it as quickly as possible in case of any massive spills. 

The two materials tie under this category.

Maintenance And Durability

If you install your subfloor with plywood, it will likely last the same period as the house. The strength of plywood exceeds OSB. Plywood also withstands moisture issues better than OSB, yet it’s not impervious to water damage and can still decay if it can’t dry when wet. Plywood, therefore, is a better option as a subfloor under a stone or ceramic tile. 

Although an OSB subfloor could also last as long as plywood, it’s slightly more flexible than plywood. For this reason, it needs to be thicker than plywood when used as a subfloor. OSB isn’t the best option under heavy floorings such as stone and ceramic tiles. 

Here, plywood is the clear winner since it’s a stronger material and works better and different flooring conditions, including stone and ceramic tiles. 

Installation

Both materials undergo the same installation process. However, most construction workers prefer plywood since its installation is easier and makes for a stronger and more secure subfloor. 

OSB has less holding power for nails and screws. It’s also more brittle and heavier than plywood. 

Under this category, therefore, plywood is the clear winner.

Cost

When you visit most home improvement centers, you’ll get a 4 x 8-foot plywood subfloor or 3/4-inch thickness going for $40 to $60 a sheet in 2022. 

An OSB material of the same size with 23/32 inches goes for $30 to $45 per sheet in 2022. It is about 20% less compared to plywood. You’ll save more money working with an OSB over plywood. 

Under this category, OSB is a clear winner since it’s cheaper.

Sound and Comfort

Plywood is about 10% stiffer over the span between joists and thus may flex less underfoot than OSB. However, not many people can notice this. 

OSB is more flexible than plywood, meaning that it can flex underfoot when installing it under sheet vinyl or carpet. However, you’ll never notice such a situation with either wood flooring or ceramic tile. 

Plywood and OSB tie under this category of sound and comfort. None is superior to the other. 

Resale Value

As we have seen above, plywood is a more strong material. Many homebuyers, therefore, place a small premium on plywood subfloors. 

OSB has a lower resale value than plywood due to its lower strength.

For this reason, few homeowners prefer OSB in their homes.

Apart from costs, plywood is superior in all the other areas, such as the strength of the structure. For this reason, it’s a superior material for use on the subfloor. It’s also the most preferred and used material in the industry. 

However, the differences between the two aren’t very significant. OSB’s cost-saving makes it an acceptable material for subfloor applications. 

It would be best to research before settling on the best subfloor material for you. 

What Is The Best Material For A Subfloor?

Several materials are used for subfloor purposes. However, you might be wondering which are the best options available. Selecting the best material is key to avoiding subfloor-related problems in the future.

Let’s look at the available and best materials options:

Wood Plank

Wood planks were commonly used in older houses but have been replaced with plywood and OSB. Planks come in sizes 1×6 and are created from softwoods, including pine. They are then installed into wood joists using standard box nails.

However, standard box nails loosen with time, leading to squeaky floors. Therefore, fluted and ring shanks are a better option because they provide resistance to pulling out. 

Plywood

Plywood is by far the best material you can ever find in the industry. It’s also the most popular and commonly used material for subflooring. This material has been in use since the 1950s and remains the most preferred material by most contractors. 

You can use standard plywood as your subfloor material. However, the best option is the ¾-inch tongue-and-groove plywood subflooring. It has interlocking edges that restrict movement on the panel edges, making the subfloor stiffer.

Plywood panels are glued to a floor joist using construction adhesive and then fixed using fluted or ring-shanks subflooring nails. 

Thinner subflooring ½-inch or ⅝-inch is ideal for low traffic floors with resilient or carpeting finishes. 

Oriented Strand Board (OSB)

The OSB subfloors are installed in most new homes today and are the next best product for wood floors after plywood. Both have several similarities both in performance and the installation process. One benefit of OSB is that it has a lower cost.

Concrete Slabs

Concrete slabs that are durable, steady, smooth, and hard subfloor options. Concrete slabs are found in basements and slab on grade foundations. You can install finishing flooring options such as stones and tiles directly on top of concrete without any problems. 

Concrete isn’t impervious to vapor and water. Therefore, when installing the material in moisture-prone regions such as basements, you must incorporate a moisture barrier. 

Since concrete conducts heat into the ground, it presents several challenges to do with hardness and temperature. 

Real hardwood flooring is not suitable for bare concrete because concrete slabs can absorb and hold moisture. See our article on best flooring for concrete slabs.

Can I Put New Subfloor Over Old Subfloor?

The plywood subfloor should be a minimum of 5/8 inches thick. OSB subfloor needs to be thicker with a minimum of 23/32 inches thick.

If there is damage to the existing subfloor, it’s best practice to remove the old subfloor materials before installing new subflooring. However, if the existing subfloor is in good shape but is too thin (less than minimum) but is in otherwise good condition, you can add a thinner, second subfloor layer to strengthen the subfloor.

It’s best practice to remove old particle board subflooring and not add a second layer of subfloor over it.

The advantage of removing any old subfloor is that it gives you a chance to repair squeaks or loose subflooring.

Now, if you only have a few floor squeaks, you can fix those without removing all the subfloor. You only need to add structural screws to firmly secure the subfloor at the squeak. Before installing a new subfloor over it, re-secure the existing subfloor to your floor joists

There is, therefore, no problem with installing a new subfloor over the old one. However, we recommend that you replace the old subfloor entirely if possible.

Do I Need 2 Layers Of Subfloor?

Having one subfloor provides an excellent level of performance and foundation for your home. However, many subfloors might fail to provide a perfect surface to lay your finished floors. In such a case, adding one more layer of subfloor on top of the first would be a wise idea. 

If you want to incorporate another layer of plywood over your subfloor, you must first clean the floor to remove any grime or dirt. After you’re through with the cleaning, you should proceed to install the plywood a sheet at a time. 

However, ensure that the plywood seems to be over your subfloor to provide enough stability.

Follow the instructions below to install another layer of subfloor:

  • Acclimate the underlayment: You should store your underlayment in the room to be installed at least 72 hours before the day of installation. The process will acclimate the materials to the room’s climate and prevent unnecessary expansion after installation. It would help if you took measurements after the materials have had enough time to acclimate. 
  • Clean your subfloor: You should then clean the subfloor thoroughly to remove grime or dust. You can either employ a shop vac or a broom and dustpan. To ensure that you clean efficiently, use a mop instead. 
  • Start installing your plywood: Start the installation of your plywood each sheet at a time. They should be perpendicular to the placement of your subfloor sheets. For proper support, plywood seams must meet over subfloor joints.
  • Staple the boards in their rightful place: Staples should be applied every 2-inches around the sheet’s edge and every 4-inches in the interior. If you’re using screws or nails, space them far apart and make sure they’re slightly under the top of your plywood. 

Fill the seams: You may opt to leave ⅛-inch spaces between sheets. However, it would help if you filled these spaces using a seam filler before installing the top layer.

Frequently Asked Questions

Which is Lighter Weight OSB vs Plywood?

The weights of OSB and plywood are similar: 7/16-inch OSB and 1/2-inch plywood weigh in at 46 to 48 pounds. Using Sturd-I-Floor plywood, you’ll find it weighs about 70 pounds, which is 10 pounds less than its 3/4-inch OSB counterpart.

Which is Better for Roof Sheathing Plywood or OSB?

OSB takes longer to get wet than plywood, but it also takes longer to dry out. When OSB is used as roof sheathing, this tendency to hold moisture means it will degrade faster than plywood when exposed to chronic leaks.

Is it OK to use OSB for Subfloor?

In most areas, OSB as subflooring meets local building codes. If using OSB for subflooring, the minimum thickness is 23/32-inch, whereas plywood is a slightly thinner 5/8-inch. OSB has some advantages over plywood, primarily in that it costs about 20% less than plywood, which adds up to considerable savings on large projects.

Can I use OSB for Attic Floor?

If your attic ceiling joists are not strong enough to make into living space, but the engineer approves using the attic space for light storage, you can install 5/8-inch plywood or 23/32-inch OSB in 4-foot-by-8-foot sheets over the existing ceiling joists.

Using the 23/32-inch OSB subfloor minimum instead of 1/2-inch OSB for a walking surface in the attic will better support the weight from foot traffic and storage with less deflection.

Do You need Tongue and Groove for the Subfloor?

When installing the subfloor, you should use tongue-and-groove plywood or OSB. Tongue and groove refer to the lip and grooves along the 8-foot sides of the sheet wood panel. Tongue and groove help to lock the subfloor in place and resist separation from thermal expansion.

Conclusion

As we have seen above, plywood claims an overall advantage over OSB. It can be attributed to the plywood being a durable and stiffer option. 

It also holds up better, especially under flooring-related accidents such as flooding or leaks. You’ll experience a greater nail withdrawal strength with plywood that holds the nails in place under stress. 

However, one important thing is to follow through with the installation instructions not to mess anything up. If you lack the expertise to install a subfloor, you should involve a professional foundation expert or structural engineer.

Remember, your house is as strong as its foundation. Therefore, it would be best if you invested in the best subfloor option despite the cost of materials. 

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.
DISCLAIMER: The content published on HomeInspectionInsider.com is not professional advice. You should consult with a licensed professional and check local permit requirements before starting any project.
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