Choosing the right board for a DIY project is typically a toss-up between OSB and plywood. Both have a lot to offer, are readily available and offer strength, versatility, and value.
While there is crossover in that both are suitable for some home renovation or DIY projects, there is typically a choice to be made between the two.
OSB and plywood have distinct characteristics, so it’s important that you choose the right one. Make the wrong choice, and you could be revisiting and fixing a lot sooner than you should be. No one wants that, and this guide will ensure you make the right choice.
How do OSB and plywood differ?
OSB and plywood are popular options for DIY projects and do share similarities, but the main difference is in how they area made. Mark Irving, building expert at Build & Plumb, explains. “OSB (Oriented Strand Board) is an engineered wood panel that is made from compressed layers of wood strands bonded with adhesives.”
"Plywood on the other hand is a flat sheet of wood veneers that have been bonded together," he continues, "with the grain of each layer rotated up to 90° relative to the previous one.”
The difference in their make-up and construction is the main reason why you could choose one over the other for your DIY projects, as we'll come on to explain.
Mark has over 20 years of experience in the building sector, leading to a wealth of knowledge surrounding building and renovating that he enjoys sharing with others who are looking to complete their own building projects.
How to choose between OSB and plywood
Martin Dooley, a carpentry specialist and the founder of MD Carpentry Workshop, offers a quick summary of how to choose which board you need. "If the board is going to be hidden and you need a strong, budget-friendly sheet, OSB is often the sensible choice.
"However, if the board will be visible, painted, stained or turned into furniture or shelving, plywood is usually worth the extra money because it's easier to finish and looks better," he advises.
“Start by asking whether the board will be seen and what sort of wear it's going to get, and the right choice usually becomes fairly obvious," he adds.
Martin Dooley is a carpentry expert and the director of MD Carpentry Workshop. With decades of experience, he specialises in all aspects of carpentry, from bespoke staircases to complete home renovations.
Shop tools and boards for your next DIY project
This marine plywood is ideal for high-moisture areas. Made from hardwood veneers bonded with Weather and Boil Proof (WBP) adhesive, each sheet measures 1220mm x 610mm x 12mm.
If using plywood or OSB on a DIY project, you’ll often need to fix it to a frame. This everyday drill boasts plenty of power and includes a charger and two batteries, so it's ready to use.
Rigid and strong, this OSB measures 2.44m x 122cm x 9mm, making it a good choice for wall sheathing on timber frames. Graded 3, making this board OK for humid conditions.
Pros and cons of OSB vs plywood
Understanding the strengths and drawbacks of each type of board can help you figure out which is more suitable for your intended use. Here we break down the pros and cons of OSB vs plywood using some key characteristics:
1. Strength
“The structure of the wood strands in OSB gives it high strength and a good load-bearing capability along the length of a panel," notes Mark Irving, although plywood is equally as strong. "The pattern creates nearly equal strength in all directions, as the crossing veneers in plywood make it very rigid and capable of spanning gaps without sagging," he notes.
That said, while OSB has high strength, it can struggle with mis-handling. “The unprotected edges of OSB can be easily damaged," explains Mark, especially during transportation or installation.
2. Resistance to water
“Modern adhesives have made OSB highly resistant to delamination or deterioration when exposed to moisture for short amounts of time," says Mark Irving. "But, although it can be water resistant, it is not waterproof. Ideally, OSB should still be kept dry," he notes.
Martin Dooley adds, “if the edges are left exposed to a lot of moisture for long periods of time, they can swell.” This affects the board integrity.
Compared with OSB, plywood is less susceptible to moisture, but for higher-moisture areas, marine plywood is better. Plywood can also be prone to delamination, especially when exposed to excessive amounts of moisture; which means it can begin to separate.
3. Appearance
Martin Dooley says of OSB, “the downside is that it's not the prettiest board in the world, as the surface is rougher. It is less suitable where appearance matters,” he adds.
Whereas on the other hand, the smooth finish of plywood is a big plus. Higher grades have fewer natural defects, and there are also different wood finishes to choose from.
4. Weight
Knowing the weight of each item also matters as it might make a difference on where you want to use it and be carrying the boards.
OSB is typically heavier than standard plywood, making it more difficult to transport and handle. As such, plywood can be more suitable if you need to move several boards upstairs to a loft conversion or bedroom for example.
5. Sustainability
In the sustainability stakes, OSB is usually considered the more eco-friendly of the two, as well as usingsmaller, faster-growing trees for its timber, Mark Irving notes how, “OSB efficiently uses raw materials, produces a low amount of waste and can potentially incorporate recycled content.”
Plywood on the other hand uses timber that relies on trees that take longer to mature than OSB.
Costs and sizes for OSB and plywood
Like for like on size and thickness, OSB is typically cheaper than plywood, as Mark Irving confirms. “OSB tends to be cheaper than plywood, and can cost between 15% and 30% less for the same sheet size and thickness.
As an example, this 2440mm x 1220mm x 12mm Hardwood Plywood from B&Q is currently £27. This comparable OSB3 Board from B&Q is currently £22. A difference of around 20%, which can make a big difference on larger projects.
A common size for both OSB and plywood is 2440mm x 1220mm, though both are available in smaller sizes. In relation to the thickness, Mark says, “OSB is available in sizes ranging from 9mm to 40mm, with thicker sizes usually made for heavy-duty uses and special applications. Plywood is usually available in thicknesses of 3mm to 25mm, with thicker panels being better for structural applications."
Beyond size and thickness, OSB and plywood are available in different grades. OSB is rated from 1 - 4, while plywood is graded from Class 1 - 3 for the performance of standard plywood. There is also marine plywood, which is bonded to stricter standards and is more resistant to moisture.
OSB3 is usually a popular choice. Mark describes it as, “load-bearing OSB for use in humid conditions." Effectively, this means most DIY projects. Plywood is also graded on appearance. AB plywood is the highest grade in terms of appearance, with CC grade being the lowest.
When buying OSB or plywood, check the grade and rating to ensure it meets the needs of your project. As a general rule, what you buy in hardware stores is fine for general DIY projects. However, if you need something specialist, make sure to check before purchasing.
Where to use OSB
OSB is a popular choice for many DIY projects where appearance is not critical. This makes it a good choice for the following:
- Subflooring – OSB is the better choice for subflooring when constructing timber frames for example. It's cheaper and more flexible, and it can be covered with more aesthetically pleasing flooring.
- Wall and roof sheathing – Both OSB and plywood are acceptable, but Mark Irving recommends OSB. “OSB tends to perform better, provided that you use a moisture-resistant grade and avoid direct exposure to water.” For example, if tiling on wood, i.e, OSB, you need to add a backer board like this HardieBacker Backerboard from B&Q.
- Shed floor and roof – Martin Dooley says, “for sheds, I'd happily use OSB. It's strong, practical and extremely cost-effective, particularly for the roof and floor because nobody will see it.” It is commonly used in cheaper sheds.
If you are putting together a new shed using OSB, I recommend treating the outside-facing surfaces of it before you start building. A sealer like this Siramico Coatings Liquid Rubber Roof Coating from Amazon will help protect against moisture and prolong your shed's lifespan. Don't forget to seal the edges too.
Where to use plywood
Plywood is a popular choice for many DIY projects where appearance is important, and can be used as an alternative to OSB in some cases. This makes it ideal for the following:
- Furniture and shelving – Plywood's smooth appearance makes it an ideal choice for furniture and shelving. Mark Irving says, “it can be practical and cost-effective when building furniture, and can be used to make cabinet carcasses in kitchens and bedrooms.”
- Walls and floors – It can be used for walls on timber frames and exterior walls, as long as the right type of plywood is used. For subflooring, it can be an alternative to OSB. Ceilings are also a choice, offering a natural look or a painted finish.
- Bathrooms and kitchens – You can use plywood in high-moisture areas if it is treated/sealed and will be covered, for example with tiles. Alternatively, you can use marine-grade plywood. However, marine plywood is more expensive than standard plywood.
If you are using plywood for your DIY projects, you’ll need to know how to treat it to achieve the best finish. Our guides on painting plywood and waterproofing plywood will help prolong its life. Alternatively, you can use it as a plasterboard alternative for an interior finish.
