Exterior plywood is a type of plywood that is durable, stable, and water resistant. Mainly it is used for outdoor purposes. It is weather and moisture-resistant. It is usually made from spruce, Douglas fir, birch, oak, mahogany, and pine.
The phenolic adhesive is used to adhere the veneer layers together. This adhesive is water and fire-resistant.
Plywood is one of the most popular engineered wood products which is widely used for construction and furniture. There are more than 13 types of plywood and there are many grades. Each grade of plywood has its own pros and cons. That’s why it is very important to choose the right type of plywood for your use.
Exterior plywood is more durable and stronger than ordinary plywood. It is also expensive.
Common Uses of Exterior Plywood
Exterior plywood can be used for all types of exterior construction. It is commonly used for decks, sheds, outdoor siding, and outdoor furniture.
Its weather-resistant veneer layers and waterproof adhesive can withstand outdoor environments without warping. It does not absorb moisture easily, whereas ordinary plywood does.
As we know, exterior plywood can withstand moisture. So it is also used for interior purposes such as kitchen cabinets, benchtops, etc.
Due to its amazing durability, it is mostly used for subfloor. It is constantly in contact with the ground and moisture but performs well.
How to identify exterior grade plywood?
There are many types of plywood. They also have many grades. Each grade is made with different wood and process. We cannot use any plywood for all purposes. So it is important to identify plywood before use.
We can identify plywood on the basis of its physical properties.
- There are no voids and gaps between the layers of exterior plywood.
- The veneer sheet thickness of exterior plywood is higher than that of marine-grade plywood.
- Generally, Phenol formaldehyde glue is used in exterior plywood because it is waterproof and weather resistant.
- Exterior plywood is mostly made from fir and pine wood.
- The exterior plywood is stamped with the letter ‘X’, which means that it is suitable for exterior use.
We can also recognize exterior plywood by its name. The first letter of the plywood represents the front grade of the plywood and the second letter represents the back side of the plywood.
As in CDX grade plywood: C represents the front face of the plywood and D back side of the plywood.
Advantages and Disadvantages of Exterior Plywood
Each building material has its advantages as well as its disadvantages. Before using them, we need to know their advantages and disadvantages.
Advantages
1. A versatile
Exterior plywood is a great versatile material. It can be used for many purposes and it performs well in most conditions. It is used for exterior purposes as well as interior.
2. Durable
Exterior grade plywood is extremely durable and stronger than MDF boards. It can withstand rain, moisture, wind, and snow. Sometimes it can be more durable than hardwood and softwood.
3. Stability
Exterior grade plywood is stable in extreme conditions for several years. While ordinary plywood has gaps and voids, it absorbs moisture while the exterior grade does not.
4. Surface Finishing
Exterior plywood is made from high-quality layers. It does not contain knots or defects. Therefore, its surface is smooth and uniform.
5. A wide grade range
When we talk about plywood, we have many grade options which we can choose according to our use. All grades are readily available.
Disadvantages
1. Expensive
Exterior plywood is more expensive than ordinary plywood. Sometimes it can be twice the cost of ordinary plywood.
2. Not completely waterproof
Many plywood dealers sell exterior plywood as waterproof, whereas the fact is that exterior plywood is water and weather resistant and not waterproof.
Therefore, for long durability, you must prepare the plywood for the external environment.
3. Hard to recognize
As I have already mentioned, there are many grades of plywood. So it can be a bit difficult to identify them to the common person (who doesn’t know much about plywood).
What is the grade of exterior plywood?
Like wood, exterior plywood also has many grades. There are mainly four grades of plywood: A, B, C, and D. These grades represent the quality of plywood.
The process of making each grade is different and the quality of adhesive and veneer layers are also different.
These are some grades of exterior plywood.
1. C-D-X Grade
CDX grade is the most popular plywood grade. Here the letters C and D represent the veneer grade of both sides of the plywood, and the letter X represents the type of adhesive used in it.
CDX grade plywood uses
CDX is a versatile plywood grade. It is excellent for all types of damp applications such as kitchen or bathroom doors. It is used for external and internal use.
2. C-D Grade
Like CDX grade, CD grade also represents the veneer grade of both sides of the plywood with letters C and D, but CD grade plywood uses standard glue, while CDX uses waterproof glue. It is cheaper than CDX-grade plywood.
CD grade plywood uses
CD-grade plywood is mostly used for all types of construction. It is mostly used indoors. If you want to use the exterior then it will need to be covered with other construction material.
3. A Grade
A-grade plywood is the best quality plywood. It does not have knots and defects at all. It is mostly used for applications that have high visibility, such as furniture or cabinet doors.
How to seal plywood for exterior use?
Exterior plywood is developed for outdoor environments but it must be sealed for long-term use. Water and moisture penetrate the plywood and damage the plywood.
Proper sealing creates a protective layer between the plywood and the external environment that protects the plywood layers for a longer period of time.
Although there are many ways to seal plywood, the most efficient way is to apply double coats of polyurethane varnish.
Another method is waterproof paint: After coating the primer, you can do twice the coating of waterproof paint.
Marine Plywood vs Exterior Plywood
There is often a lot of confusion among people about Marine Plywood and Exterior Plywood. Because both of them are very similar to each other. But there is also some difference between them.
Marine-grade plywood is more durable and stable for outdoor use as compared to exterior-grade plywood. Because marine plywood is made of boil-proof glue while exterior plywood is made of WBP glue.
Marine grade plywood is one of the best grades for exterior use. It is very resistant to water and weather.
Marine grade plywood uses
Marine grade is used to build decks, boats, siding, floors, roofing, sheds, and fences.
Read : Marine vs BWP
Conclusion
Exterior plywood is a great material for outdoor and interior use. It can withstand moisture and water. It also has some cons which are important to know before using it.
