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 always debate on which is the best subfloor material between OSB and plywood. However, plywood is the most common material and is made from multiple plies of wood oriented in opposite directions. For the most reasons, plywood is much recognized because of its durability, however costly than OSB.

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

 PlywoodOSB 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 for all flooringAvoid with stone and ceramic
Cost or priceCosts $21 for 4 x 8 sheetCost $16 per 4 x 8 sheet
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-foot sheetsContains either 4 x 8 or 4 x 12-foot sheets

Which is better between these two materials? In this article, we’ll explore some of the features and differences between the two materials. 

How Should The Subfloor Be Installed?

In the process of laying or installing your tiles, an underlayment of the subfloor is necessary. The process of installing a subfloor is relatively straightforward, especially if you follow the instructions correctly.

However, if you can’t install a subfloor successfully, you should contact a professional to help you out. Follow through the steps below to complete the installation. 

Step 1: Mark the cut lines – Here, you should employ your T-square to make lines on either plywood or OSB. 

Step 2: Cut the Plywood – Here, you can proceed to cut the plywood to its proper size. You can do this by running a circular saw over the width of the board. 

Step 3: Mark the joist locations – Use the original subfloor nails to guide you in marking the floor joist locations on your wall. It will let you know exactly where you must insert the screws. 

Step 4: Lay your plywood – Here, you should lay the plywood in its rightful place on the floor.

Step 5: Insert deck screws – Proceed to run a chalk line on the floor joist to mark your wall. You can then drive screws every 8 inches on the line. 

Step 6: Attach a cement board – Take your cement board and lay it over the plywood. Finally, screw the board into your plywood at least every 6 inches.  

Can I Put New Subfloor Over Old Subfloor?

The advantage of removing any old subfloor is that it gives you a chance to repair squeaks or loose subflooring. You’ll be able to re-secure the main subfloor to your floor joists before installing a new subfloor. 

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

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.

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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. Here, 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.

What Is Better: OSB Or Plywood?

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

A plywood subfloor uses ¾-inch and ½-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. 

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

OSB is made from large, flat chips that are arranged even up to 50 layers. They are then stitched together using glue and pressed into sheets. 

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

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 makes it look like solid wood. 

The OSB also has several flat wood chips that are 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 water and holds it for longer periods. 

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. Plywood is a stiffer material and has greater strength. It’s, therefore, a better option as a subfloor under a stone or ceramic tile. 

Although an OSB subfloor could also last as long as a plywood one, the material is slightly more flexible than plywood. For this reason, it 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 ¾-inch thickness going for $21.50. 

An OSB material of the same size with 23/32 inches goes for $16.50. It is about $5 less compared to plywood. It means that you’ll save more money working with an OSB subfloor material. 

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, 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 more superior than 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 low resale value compared to plywood due to its lower strength.

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

Which Is The Better Option?

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. The cost-saving presented by OSB makes it also an acceptable material for subfloor applications. 

It would be best to carry out enough 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 the past but have now been replaced with plywood. Planks come in sizes of 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. Fluted and ring-shanks are therefore a better option because they provide resistance to pulling out. 

Plywood

Plywood is by far the best material that 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 are ideal for low traffic floors with resilient or carpeting finishes. 

Oriented Strand Board (OSB)

The OSB is another popular material used for subfloor installation. It’s perhaps the best after plywood. The two have several similarities both in performance and the installation process. 

One benefit of OSB is that it has a low cost.

Concrete

Concrete subflooring employs slabs that are durable, steady, smooth, and hard subfloor options. 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. 

Mixed Subflooring

There are scenarios in which different materials are paired together to offer better results. For instance, you might encounter cases where a concrete slab is paired with OSB or plywood elements.

One approach involves fastening 2-inch sleepers over your concrete and then covering it using plywood subflooring. 

Another option involves laying down floating subfloors made using tongue-and-groove OSB panels and sticking to rigid foam or plastic insulation base. 

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. It would therefore be best if you invested in the best subfloor option despite the cost of materials. 

Links:

https://www.diynetwork.com/how-to/rooms-and-spaces/floors/how-to-lay-a-subfloor

https://www.ny-engineers.com/blog/types-of-subfloor-materials-used-in-construction

https://www.bobvila.com/articles/526-enhanced-plywood-and-subfloor-products/

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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.

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