They look alike and are the most commonly used sheet materials in homebuilding, but OSB (Oriented Strand Board) and plywood are pretty different.
Plywood came into the construction industry first, but OSB has since become a popular choice for many. So what is the difference between the two panels, and which one should you use for your garage walls & ceiling?
Read on to see a detailed description of OSB vs. plywood, but first, here is a close look at each panel.
OSB is an engineered/manufactured wood. Although it looks similar to plywood, it is structurally much closer to particle board.
It’s made up of wood shavings and adhesive compressed together under heat and high pressure. This results in a rigid structure, perfect for many construction projects.
There are three types of OSB.
- Standard OSB: Standard OSB has no special features and are perfect for floors, walls, or roofs.
- Zip OSB: A waterproof panel made for the outer shearing of roofs and walls.
- Subflooring OSB: A smooth and robust board, usually with tongue and groove edges for easy connection.
Many people like using OSB because it doesn’t require large, mature trees to make them. The waste material from lumber milling or wood shavings from small trees can make the boards, so it’s more sustainable.
When to Use OSB
OSB doesn’t warp as easily as plywood, and accepts nails well, especially when punching them into ceiling joists or studs. That makes it ideal for exterior walls, roof sheathing, sheds, floors, etc.
The main issue is many homeowners, myself included, see the rough texture of the surface wood flakes and perceive it as cheap and inferior.
It’s impossible to have a smooth surface with OSB, unless you cover it with something like drywall. The texture will not go away even if you paint an OSB panel.
But if you’re not looking for silky smooth walls, or if the OSB will be hidden behind other things (such as in storage shelves), then OSB is a great choice considering its low price.
I don’t recommend OSB for small projects however. Tough cut edges make it difficult to cut clean lines and attach other pieces of OSB or wood.
What is OSB Like to Work With?
OSB has some unique quirks that will affect how (and where) you use it.
Since it is not one continuous piece of wood, OSB is not as rigid as plywood and tends to flex or bounce more. Therefore, in applications like flooring, you need to use thick or high-grade sheets and ensure the joists are close to each other.
Although OSB sheets resist water initially due to the adhesive, they can soak up the moisture after continued exposure. When they become saturated, OSB will swell and expand. It doesn’t normally return to the previous size when dry. Drying also takes some time.
- Very affordable
- More sustainable than plywood
- Initially water-resistant
- Usually thicker and more durable
- Expands when water soaks in
- Lower shear-strength
- Cheap-looking textured finish
Plywood combines multiple thin sheets of wood or veneer glued together with the grain in the adjacent layers rotated up to 90° to one another.
This rotation, called cross-graining, is crucial because of it gives plywood some added benefits compared to a solid piece of wood. It improves dimensional stability, so it has a higher shear-strength, and minimizes shrinkage and expansion. It also gives the panel sturdy edges, which helps when driving nails close to the panel’s edges.
A plywood board contains an odd number of sheets (usually between three and eleven), and is available in four grades:
- Grade A: Also known as the cabinet grade, this type has smoothly sanded faces with no voids.
- Grade B: Coming right after grade A, this one also has smooth surfaces but may have up to 1-inch of defects.
- Grade C: Refers to unsanded boards with multiple defects.
- Grade D: With significant rough surfaces, grade D plywood is ideal for subfloors and hidden areas.
Plywood is very versatile and works perfectly in all kinds of woodworkingandr structural projects. While plywood isn’t exactly smooth, it accepts paint well and that usually hides any defects in the wood.
What is Plywood Like to Work With?
When using plywood, here are some characteristics you need to be aware of.
Since it consists of multiple layers of thin sheets, plywood edges are not as smooth as it is on the faces. If you want smooth finishes on all sides, you need to hide it in some way.
The most common method is to use edge banding: a thin strip of wood packaged as a roll with heat-activated adhesive on the rear. Alternately, you could apply wood filler on the exposed sections, then sand it to a smooth finish once dry.
However, the most durable option is to cut and stick a thin hardwood strip to the edge using glue and nails. Even though it will leave a visible seam, the finish will withstand wear and tear better.
The thin plywood layers are fragile and can leave splinters after cutting, resulting in an unprofessional finish. Use these tips when cutting to prevent a tear-out.
- Use sharp blades with high teeth densities
- Apply a painter’s tape over the cut line
- Make sure the cutting blade always enters on the good side
- Score the cut line using a knife first
- Place foam insulation or a scrap board on the underside for support
Alternatively, you can use a track saw with a splinter guard.
Plywood is not water-resistant, but it quickly dries after absorbing moisture. However, repeated soaking and drying can lead to delamination because the adhesive weakens as the layers expand and contract at different rates.
It is better to use marine-grade plywood for wet environments because it has waterproof glue between the layers.
Knots and Voids
Knots and voids in low-grade plywood make the board weak and can jeopardize the structural integrity of the wall or ceiling. Consider buying the high-grade type to avoid these issues.
- Available in different grades, depending on the project’s needs
- Returns to original size after soaking
- More expensive
- Not as sustainable (depending on the wood used)
- Panels are usually smaller
OSB vs. Plywood: Differences
In this section, we’re going to do an in-depth comparison of OSB vs. plywood to find out which one is right for your DIY project.
OSB is available in larger panel sizes, because of the way it’s constructed. The smaller, mixed pieces of softwood and hardwood are usually shavings left over from other items. Because of this, it’s easier to make longer OSB boards, rather than find a large piece of contiguous plywood.
Since plywood is a combination of multiple thin sheets of wood, it’s tough to find boards longer than six feet long. However, OSB can be as long as 12 feet.
Both OSB and plywood are available in different qualities, usually separated into grades.
OSB has four classifications, defined by their moisture resistance and mechanical performance. Grade 1 OSB is primarily used for miscellaneous applications on furniture and inside your home, where it won’t get damp. Grade 2 and 3 OSB is used on load-bearing application in dry and wet areas, respectively. If you need something heavy-duty, jump up to grade 4, which is also suitable for wet conditions.
Plywood is also available in four grades (as discussed earlier), which gives you the option of picking the most suitable one for your project.
OSB has a rough, textured finish, but plywood is the opposite. It can have multiple styles and appearances, all determined by the outer layers.
Top-quality plywood usually has hardwood sheets on the faces like birch, maple, or beech and makes visible surfaces like walls, ceilings, and furniture have a premium finish.
With low-quality softwood on the outer layers, plywood may have knots, defects, and rough surfaces, so it is not ideal for exposed surfaces. It would work well when installing the boards underneath tiles or siding to hide the defects.
OSB is similar to low-quality plywood on appearance, so it is ideal for installing underneath a finish material like tiles or siding.
If you’re not planning on covering your walls, I recommend taking a look at OSB panels in your local home-improvement store to see if you’re comfortable with how it looks.
Even though both boards are easy to use, OSB has limited uses because it is ideal for constructing walls, ceilings, and floors. You can use it in other areas, but construction work is its specialty.
However, plywood is more diverse. You can use it for flooring, roofing, building walls, making furniture, cabinetry, and many others.
When considering durability, the key thing to look at is the water resistance. OSB is more water-resistant and absorbs water slowly than plywood.
However, it dries slowly, and once soaked, it expands and cannot return to its original size. Therefore, the board is more practical to install in areas with low dampness levels.
On the other hand, plywood is not as water-resistant as OSB but dries quicker and returns to its original shape when dry.
Aside from that, plywood is generally lighter than OSB but lacks consistency when it comes to thickness due to the varying number of layers. However, both have relatively the same load strength.
It is worth noting that plywood is a tried and tested product that has been around for a long time and is known to last 50+ years. OSB is relatively new, so it lacks a proven track record for durability.
Additionally, OSB can crack more quickly, especially along the edges, but plywood withstands impact better.
New OSB types are coming up, though, and they show signs of being more durable mainly due to their water resistance.
Installing OSB or plywood for walls and ceilings requires the same procedures, but flooring is different. OSB flexes more than plywood, so the joists must be closer together to prevent bending.
Once installed, you need to give the surface a proper paint job, and plywood gives a better finish due to its smooth surface. Some people are against painting OSB and say it is impossible, but it is possible. However, the new layer will not hide the rough texture.
Both OSB and plywood require trees to make them, but the former is more environmentally friendly because it requires smaller diameter trees. These grow fast on farms, making the production process more sustainable.
There is also the option of using chips and sawdust (waste products from lumber milling).
However, plywood requires mature, large-diameter trees that are rotary cut to produce the thin sheets to build the board. These take more time to grow and can lead to deforestation.
Other than that, OSB still goes through production using formaldehyde adhesives, which release urea-formaldehyde into the air. A 2019 environmental law prohibited plywood production using this glue, making the process safer for the environment.
Price is a vital factor to consider, and OSB has the advantage. It costs roughly $6 for a 4 x 8 panel, while a similar-sized plywood sheet goes for $10. Installation costs are the same, so there is no need to look at them.
Now that you know all about the differences between OSB vs. plywood, here are a few frequently asked questions you might have an interest in.
Is OSB better than plywood?
It depends on the application area. If it is not as damp, then OSB is better. But if the section is very moist, plywood is the ideal option. It would be best to consider other factors, such as appearance, but water resistance (durability) is the most critical one.
Is OSB more stable than plywood?
If installed properly and kept dry, both OSB and plywood have the same strength and stability.
What do you use OSB boards for?
The most common uses are flooring, roof decking, and sheathing in walls.
What is a good substitute for OSB?
Plywood is the best alternative, but you can also consider fiberboard, fiberglass-faced gypsum panels, diagonal boards, or rigid foam.
What side of OSB goes up on a ceiling?
The stamped face should face down into the room, and the screened surface with nail guides should face up.