Plywood VS OSB: Settling The Debate

OSB (Oriented Strand Board) has been the number one alternative to plywood for decades. It costs less, has about the same shear strength as plywood, and has multiple grades.

There’s always been a debate on which one to choose. The consensus is that OSB is the better choice if cost is a big factor. Others say OSB is just a knockoff imitation of plywood.

So, which one should you choose for your roofing needs? We’re here to help you answer that question. But first, let’s start with the basics.

How Are Plywood and OSB Made?

Plywood is made by layering thin sheets of wood, called veneers, on top of each other. The wood grain of each layer runs in a different direction, making plywood strong and resistant to warping. These layers are glued together with a super strong, waterproof adhesive and then pressed under heat to create a solid panel.

OSB is made from wood strands that are about 3 to 6 inches long. This means that even wonky or imperfect trees can be used, making OSB a great way to utilize wood that might go to waste. Parts of the tree are cut into strands, dried, and treated with wax, resin, and waterproof heat-cured adhesives.

What are the Differences Between Plywood and OSB?

Plywood and OSB are great choices for roofing, roof decking, siding, and subfloors. To help you make informed decisions on which material to choose, here’s a rundown of the key differences between plywood and OSB:

Aesthetics

OSB (Oriented Strand Board) has been the number one alternative to plywood for decades. It costs less, has about the same sheer strength as plywood, and has multiple grades.

There’s always been a debate on which one to choose. The consensus is that OSB is the better choice if cost is a big factor. Others say OSB is just a knockoff imitation of plywood.

Strength

In terms of shear strength, plywood and OSB are roughly the same. However, OSB will have a tougher time dealing with moisture. So, be careful sealing up the envelope when using OSB.

In most cases, plywood is better. But, when panels are exposed to water and moisture, plywood is barely better than OSB. Both get damaged when exposed to water for long periods.

Mold and Rot Resistance

Plywood absorbs water faster than OSB but it dries faster compared to OSB. This could be a major issue, especially when used as material for new roof installations.

OSB tends to puff up like a sponge when wet, especially around the edges. This happens because of the way it’s made.

Wood chips are pressed together under high pressure, and when they get wet, they release that pressure and expand. Because OSB holds onto water for longer, it’s more likely to rot or decay over time if it stays damp.

Weight

OSB is heavier than plywood. The manufacturing process makes OSB denser, so it tips the scales more. For instance, a standard sheet of plywood (23/32-inch, 4×8-foot) weighs in at about 67 pounds, while the same size sheet of OSB is a hefty 78 pounds.

This matters especially for roofing. More OSB means more weight on your roof’s structure, something to keep in mind when considering roof decking and planning your project.

Use Cases

Plywood and OSB are both popular choices for sheathing roofs, walls, and subfloors. They’re equally handy for these jobs, easy to drill into, and hold nails like a champ.

However, there’s a catch: OSB isn’t as water-resistant as plywood and can swell up when it gets wet. That’s why some builders prefer plywood for roofs and subfloors, especially in areas prone to hurricanes.

Here’s where OSB might have a slight edge: some manufacturers print gridlines on their panels, making measuring, marking, cutting, and fastening easier. But don’t worry, plywood fans – some plywood manufacturers have caught on and offer grid-marked sheathing too.

How to Choose Between Plywood and OSB?

Plywood really has that distinct look to it that even the best OSBs can’t imitate. It’s close but if you’re going off aesthetics, plywood might be the choice for you.

Still, both materials offer tons of strength and versatility for sheathing, subfloors, and siding. But both still have some drawbacks you need to consider. Here’s a breakdown to help you decide:

Why You Should Choose Plywood

Plywood’s cross-laminated structure makes it strong and flexible. It can handle heavy loads without warping or cracking making it the ideal choice for areas with lots of foot traffic.

While not completely waterproof, it handles moisture better than OSB, drying out faster, and resists rot and swelling. This makes it a top choice for roofs and subfloors, especially in humid environments. It’s also lighter than OSB, so it puts less stress on your roof’s structure.

When OSB Takes the Lead:

If you’re looking to save some cash on a big project, OSB is often the more budget-friendly choice. Its manufacturing process also gives it a consistent edge: you get a uniform panel with fewer weak spots or gaps, so you can count on its strength across the board.

It comes in larger sizes than plywood. That means fewer seams and faster installations. As a bonus, the adhesives used in OSB make it naturally resistant to decay, so you can worry less about rot.

The Plywood vs OSB Debate

The debate between plywood vs OSB really comes down to the budget. In most cases, plywood wins. OSB can catch up in terms of strength but it just doesn’t have the aesthetic that plywood brings. To recap, here are the key factors to consider when choosing between the two:

• Prioritize Strength and Moisture Resistance? Opt for plywood.
• Budget-Conscious and Need Larger Panels? Choose OSB.
• Building in a Humid Climate? Plywood is your safer bet.
• Need Consistent Strength Throughout the Panel? OSB might be a better choice

If you need roof, siding, or roof decking installation or repairs, whether you want to use plywood or OSB, Trenton Roofing has you covered. Get your free estimate today.