Everyone knows about the strength of plywood and its many applications. From its use in roofing, flooring, exterior wall sheathing to interior wall framing, plywood can be found almost anywhere. What is less know is why plywood is so ubiquitous; why is it such a strong material?
Plywood gets its strength from the layers of wood veneers used, which are placed uniformly with the grain of each layer being 90° adjacent to the one preceding it. The adhesive used in combining these layers also plays a huge part in the strength of plywood.
I don’t need to tell you about the different types of plywood, its additional benefits, or the factors that affect its strength, do I? Well, if I do, why don’t you pull up your plywood chair and let me inform you of the wonder that is plywood.
Why Is Plywood Such a Strong Material?
Plywood is a common material that you can use as an alternative to solid wood because, in most cases, it looks similar to solid wood and does most of the same things that solid wood does.
Plywood is an artificial material manufactured using multiple layers of thin wood called wood veneer.
These wood veneers are arranged with the grain direction of each layer being 90° adjacent to the veneer preceding it. This is done so that the weakness of the grain in one layer would not affect the weakness of the grain in the next. This therefore elevates the overall strength and tenacity of the material.
Another factor that adds to the strength of plywood is the adhesive used to combine the layers of wood veneers. This adhesive acts as a bonding agent that gives the layers a solid form and inhibits them from coming apart. After the adhesive is applied, these layers are heated at 140 °C to form plywood.
The structure of plywood differs from solid wood because all grains in the product are facing one direction and are further apart than in plywood. Solid wood also has knots that can go through the entire product, weakening it; this is not found in plywood (except in a few layers as they come from different trees)
What Factors Affects Plywood Strength?
You probably know all about plywood, its versatility, and how it can be applied in so many sectors. This versatility is due to the different levels of strength it possesses. There are several factors that determine the strength of this sturdy material; they are the type of wood used, the number of layers, and the type of adhesive applied.
Type of Wood
The first determinant of plywood strength is the species of wood used to make it. There is softwood (conifers or gymnosperms) and hardwood (angiosperms or dicotyledons) plywood.
Softwood plywood is mostly less dense and lighter than its hardwood counterparts. Due to its softer nature, it is used for windows, ceilings, doors, and decorating purposes. Softwood plywood is made from softwood like pine wood, cedarwood, or mango wood.
Hardwood plywood has higher strength than softwood plywood which is why it is used to make items like chairs, beds, flooring, sporting equipment, toys, or skateboards. Some examples of hardwood are teak wood, oak wood, alder wood, and birch wood.
There are some exceptions that cross the line between softwood and hardwood. A good example is pine wood, considered softwood but can also be used as hardwood in flooring.
Number of Layers
As I mentioned earlier, plywood is made by the layering of wood veneers. The strength of plywood is directly proportional to the number of layers of wood veneers used. The more layers used, the stronger the plywood will be.
“Weaker” plywood tends to have fours layers or less, while mid-level strength plywood would have four to seven layers. The most robust plywood tends to have more than seven layers.
The thickness of plywood established by the number of layers is also a factor in its strength. The most commonly used plywood is ¾ inch thick, but if you plan on doing some heavy construction work, you need 1-inch thick plywood.
Another trick to layering that gives plywood its strength is the rotating direction in which the wood veneers are layered. So, if one layer of the plywood were the break in one pattern, the pattern of the next layer would stop the breakage from continuing.
Adhesive
Plywood is only as strong as the adhesive used to combine the layers. A good adhesive works by blocking plywood pores, stopping humidity from damaging the plywood and possibly causing the layers to separate.
Some manufacturers use a high-grade adhesive on specific softwood plywood, which can make the plywood stronger than hardwood plywood over a period.
What Are the Application of Plywood?
Plywood has been a great discovery and is used for so many purposes. With plywood, the possibilities are endless. Here are some applications of plywood:
- Exterior Wall Sheathing
- Interior wall
- Roofing
- Flooring
- Furniture
- Cabinets
- The internal frame of vehicles
- Fences
- Scaffolding materials
- Sports equipment
- Musical instruments
- Skating arenas
- Interior of game stadiums
- Ship construction
- Space or aviation parts
- Car sound insulation
- Movie set
- Packaging of various products
- Toys making
- Children playgrounds
- Traffic signs
- Billboard boards
What Are the Other Benefits of Plywood?
Strength isn’t the only thing plywood has to offer. While it is a defining characteristic and probably the most known fact about plywood, there are other factors that make plywood the primary choice for many projects and a fantastic alternative to solid wood.
Durability
Since the layers of wood veneers used are placed against their grains, plywood is less likely to break than solid wood. Using high-quality veneers and adhesives also adds to the durability allowing the plywood to resist the many abrasions endured on a regular basis.
Lightweight
Despite all its robustness, plywood is surprisingly light, making it perfect for several purposes like furniture and other projects requiring bulk lifting it.
Variety of Size
Plywood comes in several sizes, from small to large. So, for a simple project, you can use a smaller size. But, for a larger project, you can use a bigger size. A single sheet can come with dimensions of as least 180cm x 120cm. A larger sheet can cover a wider area leaving no gaps or uneven ends.
Eco-friendly
Obviously, nothing about creating or using wood is eco-friendly; however, plywood is made using lesser wood than solid wood. This means that more timber is saved and can be used in the making of more plywood.
Affordable and Budget-friendly
The price of plywood is lower than solid wood, and each is just as effective as the other, which makes it the go-to product for buyers.
It should also go without saying that if you were to use plywood for your project, you would be able to use every single sheet of the material, leading to little wastage.
Is Plywood Better than Solid Wood?
Neither plywood nor solid wood is better than the other. They are both incredible materials that have made the construction of so many objects possible. Each of these materials possesses features that make them ideal in certain areas than the other.
Applications
Plywood is applied in areas that need sheet material that does not crack, warp, or shrink. Examples include crates, cabinets, wardrobes, and curved surfaces like skateboard ramps.
On the other hand, solid wood has always been applied in areas requiring strength and stiffness, like flooring and bookshelves decking. It is also preferable in the regions that require beauty or aesthetics.
Strength
People have always argued about which material is stronger. The answer is solid wood. Solid wood is much stronger than plywood, especially where stiffness is involved. A bookshelf carrying books is more likely to stay linear if solid wood instead of plywood is used.
Solid wood is more susceptible to weakness due to atmospheric change than plywood. In extreme cases, the solid wood could either crack or split, which is not a problem for plywood. However, the layer in plywood may separate due to humidity depending on the adhesive used.
Maintenance
Plywood surfaces are easier to maintain because they are resistant to scratch and moisture. All you have to do is wipe the surface with a damp cloth, and it will be as good as new.
Unfortunately, solid wood is not laminated, which means it will age and change color over time. You can quickly fix this by sanding and then polishing the surface every couple of years.
Price
Since there are guidelines in place to give wood plantations enough time to grow, the supply of wood is limited, which leads to high demand and low supply. This increased demand and low supply is the reason why solid wood is more expensive than plywood.
In many cases, the absence of solid wood is not noticed due to the presence of a similar and more affordable material, plywood.
What Is the Difference Between Plywood and Laminated Wood?
Of all the alternatives to solid wood, plywood and laminated wood are two of the most common. They are both manufactured and possess wood particles. Although, laminated wood uses less wood than plywood, making it more eco-friendly.
Like you should already know, plywood is made up of layers of sheets called wood veneer that is arranged in a way that makes their grains defer from the before them.
Laminated wood is also made up of layers; however, these layers are not wood veneers; they are laminates. Laminates are manufactured from melamine resin, high-density fiber, or wood particles. In laminated wood, the grains of the laminates are parallel to each other, as opposed to the right angle placing in plywood.
Laminated wood does not look like natural wood, so it is imprinted with various images to give the appearance of wood. Laminated wood also has a transparent protective layer that makes it scratch-resistant and easy to maintain.
The life span of laminated wood is relatively short and lasts between 10 years to 20 years, while plywood can reach up to 30-40 years. Laminated wood tends to be thinner than plywood which is probably why it is cheaper.
Disadvantages of Plywood
While the possibilities for plywood are limitless and its existence has been of astounding benefit to the world, there are some disadvantages to plywood that you should be aware of.
- Although plywood is strong, it is not as strong or dense as solid wood, making it seem less appealing to use sometimes.
- Most times, you cannot be sure of a plywood’s thickness because manufacturers’ claims are not always accurate.
- Plywood made of wood veneers like black nut tends to be thin, which makes it a poor choice for areas that we use on a regular basis, like public areas or areas in a home with active children or pets.
- Longer plywood is not suitable for applications in places where heavy usage occurs because plywood tends to sag from the middle in these cases. Some areas it is not ideal in include front doors, bookshelves, or wardrobe doors.
- As you know, plywood is made of wood veneers. However, it isn’t easy to decipher what exact wood was used to make the plywood. This lack of knowledge might lead you to buy plywood that does not fit your requirement,
- Plywood is not as attractive as solid wood, which comes with naturally stunning patterns. This means that plywood needs to be covered with a layer of laminates (such as Sunmica) to increase its beauty, durability, and resistance to water.
- If you look at plywood edges, you will see all the layers of wood veneer used. This can make a home or wherever plywood is being used look unattractive. Although, you could always just use laminates of veneers on the surface, which is not an easy task for those new to woodworking.
- Some adhesives used to stick the wood veneers together are not always eco-friendly. Urea formaldehyde is not very safe for use, can cause cancer, and also pollute the environment. These adhesives are why some plywood doesn’t smell as good as solid wood when brand new.