Plywood has been around for centuries, but it hasn’t always existed in the way we know it today.
In the modern world, plywood is used for all manners of residential construction projects, including cabinet building, sheds, subfloors, wall panels, and bathroom vanities. However, years ago, it was used for underground tunnels and minor building work in ancient Egypt.
Over 2 million cubic meters of the material is sold every year, and the industry value keeps on rising (according to Statistica). Plywood is a fascinating invention the world has seen and there’s a lot to learn about the building material.
Keep reading to learn our top five interesting facts about plywood.
5 Interesting Plywood Facts
Plywood Comes in Grades A-D for Strength, Discoloration, Defects & Moisture-Resistance
More than 10+ variations of plywood exist, including softwood, hardwood, marine grade, aircraft, and overlaid.
Each type of plywood comes in four set grades: A, B, C, or D. The grades given depend on the quality of the sheet, plies, and glue used. Higher quality grades are more expensive than lower grades.
Grade A is the highest quality of plywood available. It is strong, has minimal defects/knotholes, has a high resistance to water, and doesn’t discolor easily.
For this reason, it’s best used for furniture or cabinet doors, particularly in high humidity areas (like bathrooms or kitchens). Grade D is the lowest quality of plywood and is therefore the cheapest.
Each Layer is Rotated 90 Degrees to Prevent Warping & Improve Strength
When plywood is made and the core layers are bonded together, they aren’t molded together in the same direction, like natural wood.
Each layer is purposely rotated 90 degrees before gluing. This makes the wood stronger and more resistant to stress without splitting or warping, which is why it can be used for subfloors.
Likewise, unlike natural solid wood, the change in direction of wood grain enables screws or nails to secure into the wood better.
The varying grain also offers better compression for nails or screws to remain in the sheet. However, despite this, screws are typically better to use in plywood vs nails.
Inner Layers are Stronger Than Outer Layers
Plywood is made by compressing thin ply layers together using heat and glue to produce a reinforced sheet of wood.
When treated and sealed properly (like with epoxy or polyurethane if using the sheets externally), plywood can last up to 35 years, potentially longer if used internally.
When plywood is constructed, the inner layers are usually made of cheaper wood, while the outer layers are made from stronger, higher quality wood.
How strong each ply layer is depends on the quality (grade) of the sheet. Higher grades will likely use better quality wood for the inner core veneer layers compared with the outer layers.
How Plywood is Glued Impacts Use
Different types of glue can be used to bond plywood sheets together. The most common are urea formaldehyde, melamine, and phenolic glue.
Most plywood is created with urea formaldehyde. It offers the strongest hold over prolonged periods, which makes plywood last longer.
This is particularly important when using plywood for subfloors or roof sheathing. Phenolic glue is often added to urea formaldehyde glue to make the boards more waterproof.
Melamine is not the strongest or most durable type of glue, so it’s often found in cheaper plywood.
Plywood Was Invented in 2600 BC by the Ancient Egyptians
Despite plywood being a modern engineered wood product, it was invented almost 5,000 years ago by the ancient Egyptians. Similar inventions were found in ancient Greece, with scribing depicting the construction process.
Alike today’s processes, plywood was made by manually stripping wood into thin veneer plies and gluing them together to form a bonded plywood sheet.
Plywood is one of the most universally popular materials for interior and exterior construction projects across the globe. According to Statistica, around 2 million cubic meters of plywood are sold every year.
In the US alone, the plywood market is expected to reach over $15 billion by 2030 (source), with significant growth predicted between 2022-2030 in response to its ever-growing popularity.
Used for both residential and commercial building projects, it’s one of the most versatile and affordable wood products on the market.
It’s strong, durable, water-resistant, and comes in a variety of grades and finishes to suit every construction project. It’s also easy to use, cut, paint, stain, and finish.
Additionally, plywood is widely available in convenience stores across the US and the rest of the globe.
What is the Advantage in Using Plywood Material?
Plywood is widely used because of its advantages, which include:
Strong – Able to withstand heavy weights
Durable – Can last up to 35 years in most woodworking products
Water-resistant – Can withstand a high degree of moisture (particularly marine grade plywood)
Affordable – Costs between $12-$55 per standard sheet, and up to $120 for higher grade/thicker boards
Why Plywood is Used Instead of Wood?
Plywood is a cheaper, stronger, and more widely available wood product compared with solid wood.
While solid wood is strong, it is heavy, more expensive, and prone to splitting when force is applied. It is also less widely available and therefore more expensive than plywood.
On the flip side, plywood is strengthened, highly versatile, and offers significantly better resistance to brute force.
The average plywood sheet can support between 5-50 lbs per square foot. Thicker plywood, between 1 inch and above, can support as much as 170 lbs per square foot. Size also matters when it comes to how much weight plywood can bear.
How Long Does Plywood Last?
Because plywood is specifically manufactured to withstand brute force and provide structural support, it has a high durability and lifespan. Plywood can last up to 35 years, sometimes more.
When used outside, how long plywood lasts depends on how well it’s treated and what the weather conditions are like. Coated with epoxy or polyurethane, plywood can last for years outside in window frames or outbuildings. If left untreated, sheets are likely to rot within 1-3 years.
Generally, plywood is a strong wood alternative that can be used for almost any residential construction product. This includes heavy-duty reinforcing projects, like wall and roof sheathing, floor leveling, and reinforcing subfloors.
An average plywood sheet of ¾ thickness can hold up to 50 lbs, depending on its size.
However, not all plywood is strong enough to be used for structural reinforcement. Small, ¼ inch-thick sheets can only withstand around 5 lbs of weight and are therefore not considered strong.
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